- Email: [email protected]
Loaded dipole antennas with new CRLH cell configuration
Accepted Manuscript Regular paper Loaded Dipole Antennas with New CRLH Cell Configuration Mahmoud A. Abdalla, Mohamed H. Ghouz, Mohamed Abo El-Dahab PII: DOI: Reference:
S1434-8411(16)31503-5 http://dx.doi.org/10.1016/j.aeue.2017.06.029 AEUE 51947
To appear in:
International Journal of Electronics and Communications
Received Date: Revised Date: Accepted Date:
16 December 2016 18 June 2017 25 June 2017
Please cite this article as: M.A. Abdalla, M.H. Ghouz, M. Abo El-Dahab, Loaded Dipole Antennas with New CRLH Cell Configuration, International Journal of Electronics and Communications (2017), doi: http://dx.doi.org/ 10.1016/j.aeue.2017.06.029
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Loaded Dipole Antennas with New CRLH Cell Configuration Mahmoud A. Abdalla1, Mohamed H. Ghouz2, and Mohamed Abo El-Dahab2 1,
Electromagnetic Waves Group, Department of Electronic Engineering, Military Technical College, Cairo, Egypt.
2
Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Cairo, Egypt 1
[email protected]
In this paper, two different triple band dipole antennas loaded by new modified composite right left handed cell are presented. The modified cell can introduce large electrical length in small size. Thus, the two antennas are designed with smaller operating frequency or reduced physical length compared to a single frequency reference dipole. The designed antennas can serve different wireless services for GPS (1.27 GHz and 1.55 GHz), UMTS (1.85 GHz), and WiFi (2.4 GHz) in triple band functionalities. The lower operating frequency antenna size is (70 70 mm2) whereas the reduced physical length antenna size is (60 70 mm2). At mid band frequencies the reduced frequency antenna length is (0.29 0, 0.37 0, and 0.52 0), whereas that of the reduced physical length is (0.28 0, 0.41 0, and 0.56 0), at triple band mid frequency, respectively. Compared to a typical dipole antenna, the designed loaded dipoles can achieve a length reduction that can reach up to 50%. Moreover, the antenna has good gain at the triple bands (-1.2 dB, 1.9 dB and 3.5 dB for reduced operating frequency antenna and -3.1 dB, 1.2 dB and 3.4 dB for the reduced length antenna. The two antennas have good radiation efficiency that can reach up to 84% on a low cost antenna substrate. The mathematical analysis, full wave simulation and experimental measurements of the reported antennas are introduced. Keywords: Metamaterial, Composite right/left-handed (CRLH), Printed dipole antenna, Multi-band antennas. Corresponding author: Assoc. Prof. Mahmoud A. Abdalla, email: [email protected]
I.
INTRODUCTION
With the continuous development of mobile wireless service, there is a need for devices that integrate all these services. Also, the customer requirements of compact handheld devices have forced the front end engineers and researchers to introduce new techniques in design microwave components and antennas. As a contribution of the antenna design, a multi band antenna with good gain and omnidirectional radiation pattern has become a recent high challenge [1]. In designing planar multi band antennas, different techniques have been suggested by researchers. These techniques can be summarized as either using (1) separate resonators [2],[3], using incorporated resonators [4]-[6], loading a monopole/dipole with additive resonance circuits [7],[8] and by using fractal shapes [9]. The trade off in these techniques is the design flexibility for arbitrary functioning frequencies, almost unchanged
omni directional pattern and off course small antenna sizes. In order to contribute in this trade off challenge, it has been suggested over recent few years to load conventional resonant antennas with novel metamaterial (MTM) structures. The metamaterial structure, which was first suggested by Veslago can introduce artificially engineer constitutive parameters and hence phase propagation coefficient which can be designed to be arbitrary. Composite right left handed [10] or negative refractive index [11], are suggested as having negative electric permittivity and magnetic permeability. Propagation through these structures has two modes of operation; left handed mode characterized with negative phase propagation constant and right handed mode characterized with positive one. These characteristics have been employed to change the electrical length of many resonant antennas (e.g. monopole/dipole and loop). Accordingly, compact wide band / multi band loaded monopole antenna [12]-[15], loop antenna [16] inverted F antenna [17], [18] and E antenna [19] have been suggested. Also, some attempts for metamaterial loaded dipole antennas have been also suggested [20]-[23]. Also, these structures have achieved multi / band small antennas, but most of these antennas have small gain [24]-[27]. However, achieving triple band functionality with good gain is not discussed in literature, up to the author's knowledge. In this paper, we suggested a modified CRLH to load a dipole antenna to design a good gain triple band antenna. The modified cell is realized in Π-Section CRLH configuration with virtual ground. Thanks to this cell, up to 50 % size reduction in physical length of the dipole arm or the operating resonant frequency, compared to conventional dipole, can be achieved. This two features will be introduced in two designs identified as (RL Design) and (RF Design), respectively. The antennas are designed to function at the following services: Wi-Fi (2.4 GHz), Digital cellular service (DCS) (1710-1880 MHz) and GPS (1.227 GHz, 1.57 GHz) bands. Through the paper, the full wave simulation was done employing the commercial software Electronics Desktop (HFSS) from ANSYS.
II.
Multi Band CRLH Dipole Loaded Antenna Concept
The CRLH loaded dipole antenna is constructed by loading the dipole arm with Π-section CRLH cell. Hence, the total electrical length of the dipole arm will be equivalent to its linear unloaded physical section and the non-linear one over the CRLH cell. For achieving good gain, the CRLH cell position was chosen to be at the edges of the dipole arm. The mathematical expression of this principle is expressed as
Total Dipole CRLHcells n , n 0, 1 2,...
(1)
where Dipole is the phase shift along the two dipole arms (positive), CRLHcells is the phase shift of the loading cells (arbitrary positive/negative/zero) and hence Tot is the total loaded dipole phase shift. The more the condition in (1) is satisfied, the possible resonance and hence an antenna band functionality are achieved. To obtain triple band dipole operation, the dipole resonance condition in (1) is satisfied with n = -1, 0 and 1 as will be verified later. The suggested Π-Section loading CRLH cell configuration is shown in Fig. 1 (a). It is formed by cascading a series interdigital capacitor (Cse) and two shunt meander line inductors (Lsh) whereas the elements (Lse and Csh) are the cell parasitic elements. The dispersion propagation (The guided propagation phase constant (β) variation against frequency) along this cell can be explained by applying the periodic analysis of microwave network over a periodic distance (d). In details, this can be found by finding the ABCD matrix of the unit cell and applying propagation condition (cos (d)=A) as explained in [28]. Hence, the dispersion equation can be written as cos d 1 ZY
(2)
where Z j Lse 1/ jCse
Y jCsh 1/ j Lsh
Fig. 1. cell
(3-a) (3-b)
(a) Π-Section CRLH cell equivalent circuit, (b) The topology of Π-Section CRLH
The reference printed dipole antenna was designed to operate at 2.4 GHz. Since the dipole is unloaded, then its length was calculated in (1) such that CRLHcells = 0 and Total = . The 2D layout of the reference dipole is shown in Fig. 2 (a). The dipole antenna is fed by a 50 SMA
connector. A balun between the feeding microstrip line and the dipole arms has been employed to have balanced feeding and matching the antenna to 50 . The reference dipole, and all proposed dipoles in our paper, are printed on a low cost FR4 substrate with thickness h=1.6 mm, dielectric constant r = 4.4 and loss tangent =0.025. All dimensions are tabulated and presented in Table I. The simulated current distribution along the dipole at 2.4 GHz is shown in Fig. 2 (b). As shown in the figure, near the edges, the current is minimum (poor radiating parts). So the designed Π-CRLH cell length was desired to be realized in no more than 9 mm starting from the dipole arm open circuit side. This should ensure the reasonable antenna gain at the resonance frequencies as mentioned above.
Fig. 2. (a) Reference printed dipole antenna geometry, (b) The Current distribution along the reference dipole antenna
III.
Triple Band Dipole Antennas
The design procedures and results of the RF design and RL design are discussed in this section. The fabricated RF Design dipole antenna is shown in Fig. 3 (a) whereas the RL Design is shown in Fig. 3 (b).
A)
Π-Section CRLH cell Triple Band Dipole Loaded Antenna (Increase Elec.
Length (RF-Design)) In this section, the concept of Π-Section loading CRLH is used to increase the electrical length of the dipole while maintaining the same physical length of the conventional dipole. Our main challenge was to realize a cell that fulfills the equivalent circuit of the explained ΠSection CRLH and at the same time does not occupy large size of the dipole size to maintain high gain as well. So we have used a dual vertical back to back cell which is shown in Fig. 2
(b). It can be observed that an interdigital capacitor is employed as C se whereas the shunt inductor Lsh is realized using meandered line strips with virtual ground on the substrate bottom. The elements (Lse and Csh) are parasitic elements exist in the cell. All dimensions are tabulated in Table I. TABLE I: The Used Parameters Values for the, reference dipole, RF Design and RL Design Dipole Antennas
Par.
Ref. Printed Dipole
RF Design Dipole (Π -CRLH Cell with increased Electrical Length
RL Design Dipole (Π- CRLH Cell with reduced size)
Ws
75
75
60
Ls
75
75
70
Wd
7.5
7.5
5
Ld
55
55
40
gap
0.6
0.6
0.6
Wf
3
3
3
Lf
23
23
28
Wcp
9.7
9.7
7.2
Lg
15
15
10
La
36
36
36
Wng
--
0.3
0.3
Lng
--
4.3
4.3
S
--
0.5
0.5
L
--
7
6
Wl
--
0.6
0.6
Lm1
--
1
1
Lm2
--
4
4
Lm3
--
0.75
0.5
All design parameters are in mm
Fig. 3. Fabricated Π-Section CRLH loaded dipole antennas (a) Increased Electric Length (RF Design) (b) Reduced Length / Size ( RL Design)
The triple band loaded dipole has the same arm length (55 mm) as the reference dipole antenna (functions at 2.4 GHz) but its triple bands were adjusted to be at 1.27 GHz, 1.55 GHz and 1.9 GHz. This was achieved by employing the Π-CRLH cell as follow. (1) According to the current distribution over the dipole (shown in Fig. 2(b)), the cell should occupy no more than 9 mm at the two dipole ends. (2) Based on the remaining conventional dipole length remaining un-loaded (37 mm), the cell was designed to have a positive phase shift which is approximately 30o at 1.9 GHz. Hence, the zero phase shift; the transition between left and right handed pass bands was designed to be as initial value at 1.7 GHz. (3) To achieve a second band at 1.55 GHz, a total zero phase at this length had to be achieved; Thus, the ΠSection CRLH cell should achieve a left handed phase equals to -33o at 1.55 GHz. (4) To achieve a third band at 1.27 GHz, an –180o phase at this length had to be achieved, corresponding to n=-1 in (1). Based on that the Π-CRLH cell should achieve a left handed phase equals to -105o at 1.27 GHz. (5) In order to achieve good matching properties at the triple bands the cut off frequencies of left handed pass band and right handed pass band were chosen to be 1 GHz and 3 GHz, respectively. However, it is worth mentioning that some variations of these values were changed in the realization stage and some fine optimization tuning was applied. These requirements are satisfied by the following design equations as
fcl
f ch
1 4
1
1e9
LL CL
1
1
LR C R
(4-a) 3e 9
(4-b)
LL CR LR CL
d a cos1 1 ZY
1.7e
9
(4-c) 0o
d a cos1 1 ZY
1.9e
d a cos1 1 ZY
1.5e
d a cos1 1 ZY
1.2e
9
9
9
(4-d) 30o 33o
105o
(4-e) (4-f) (4-g)
Since the degree of freedom we have is four, so equations (4-a)-(4-d) were used whereas (4e)-(4-g) were satisfied in layout simulation stage. Based on the designed values, the detailed realization for the topology in Fig. 1 (b) was done. To confirm the designed values and the layout before loading it in the dipole, the dispersion analysis over the designed cell in Fig. 1 (b) had to be studied and compared with design objectives in (4). Accordingly, the cell topology in Fig. 1 (b) has been simulated in HFSS as a two port network. The validation has been done in the next explanation using two different techniques for further validation. First, in Fig. (4-a), the dispersion diagram based on the HFSS simulated scattering parameters (magnitudes and phase) using (5) 1 S11S22 S12 S21 d cos 1 2S21
(5)
It can be observed that the zero phase is achieved at 1.7 GHz and LH and RH pass bands cut off frequencies are (1 GHz and 3.1 GHz), close to designed values equations (4-a) and (4-b). Since the dispersion analysis requires an infinite structure, which is not our case, thus, exact phase shift values for only one cell. Therefore, the phase and magnitude of the transmission coefficient (S21) for the simulated cell are plotted in Fig. 4 (b). It is worth to comment that in typical condition, the passband dispersion diagram in Fig. 4 (a) should have the same message has been obtained from phase of S21 (only within the passband that is identified with magnitude of S21 close to 0 dB). In Fig. 4 (b), it can be observed that zero phase frequency is 1.7 GHz. The LH and RH cut off frequencies are 1.1 GHz and 3.2 GHz, respectively.
Comparing these values to those in Fig. 4 (a), we can observe a little shift in frequencies due to the ideal conditions in Fig. 4 (a). Also, we can observe that cut off frequencies in both Fig. 4(a) and Fig. 4 (b) are slightly shifted from the design objectives in (4). The shifts are due to the effect of the elements that can not be totally imposed in the design equations. However, these values still can meet the desired triple band frequencies at (1.27 GHz, 1.55 GHz and 1.9 GHz).
Fig. 4. The Π-Section CRLH cell employed in RF-Design (a) The dispersion diagram (b) The transmission coefficient (magnitude and phase)
The designed Π-CRLH cell was then loading the dipole arms. The simulated and measured reflection coefficient of the loaded dipole is shown in Fig. 5. It is obvious that the antenna’s reference resonance has been shifted from 2.4 GHz to 1.9 GHz and two new resonances have been introduced at 1.27 GHz and 1.55 GHz Therefore, we can claim that the Π-CRLH cell contributes to the dipole phase and satisfy (1) at n = 1 at f= 1.9 GHz whereas LH band adds leading to another band at n= 0 generating another resonance at 1.55 GHz. and at n=-1 generating resonance at 1.27 GHz.
Fig. 5. The simulated and measured reflection coefficient of increased length triple band laded Π section CRLH dipole antenna (RF Design)
B)
Π-Section CRLH cell Triple Band loaded Antenna (Reduce Antenna Size
RL-Design) In this section, a Π-Section CRLH loading cell is used to reduce the physical length while having the same electrical length. This second introduced loaded dipole antenna has the same reference dipole antenna frequency (2.4 GHz) but its single arm length (40 mm) is reduced with 25 % and introduced another frequencies at 1.25 GHz and 1.8 GHz. Design dimensions are tabulated in Table I as RL-Design. Similarly, the design have been carried out as explained above, with some optimization in the full wave simulation stage. The simulated and measured reflection coefficients of the RL-design loaded antenna compared to the reference antenna is shown in Fig. 6 with good agreements between results. Finally, a comparison between the proposed antennas are summarized in Table II. The comparison demonstrates competitive features in terms of its compact size and good gain.
Fig. 6. The simulated and measured reflection coefficient of decreased physical length triple band loaded Π-CRLH dipole antenna (RL Design).
TABLE II A summary of the Deigned Antennas Parameters (RF-Design and RL-Design) Antenna Service Frequency (GHz)
RL-Design
1.27 GHz, 1.57
1.25 GHz, 1.8 GHz
GHz and 1.9 GHz
and 2.4 GHz
18, 14.5 & 19
10, 8.5 and 20
-1.2, 1.9 and 3.5
-3.1, 1.2 and 3.4
65, 76 and 80
42, 60 and 84
Substrate (r) / thickness (mm)
4.4/1.6
4.4/1.6
Physical Substrate Size (mm mm)
75 75
60 70
-10 dB Fractional bandwidth (%) Gain (dB) Efficiency (%)
C)
RF-Design
Radiation Properties of Triple Band Antennas
The simulated normalized E/H radiation patterns of the two dipole loaded antennas (RFDesign / RL-Design) are shown in Fig. 7 (a)–(f) at the triple band operating frequencies. It obvious that the radiation patterns at all cases are like Omni-directional (directive in E plane
(=0o) and isotropic in H plane (=90o)). In other words, the patterns resemble the conventional dipole antenna pattern. This also can be confirmed by investigating the 3D simulated gain patterns at operating frequencies. The simulated gain values of the antennas in this work were calculated where they vary from -3 dB to 3.4 dB. Also, the simulated efficacy was calculated and it vary from 68% to 83%. These results confirm that the proposed loading succeed in achieving good gain and triple band functionality which is quiet good for a wireless applications.
Fig. 7. Simulated and measured radiation patters of triple band laded Π section CRLH dipole antenna (RF-Design (a-c) and RL-Design (d-f)).
Finally, a comparison between the introduced antenna and recent triple band compact size antenna are summarized in Table III. As we can observe that the table that the proposed antenna has good competitive parameters compared to recent published work. Also, it is worth to comment that the proposed antenna has suitable bandwidth for wireless services which is neither too large to suffer interference nor too narrow to affect the service.
Table III: A comparison between triple band antennas (recent published and the loaded dipole antenna in this work)
Reference
[This Work RF Design]
[This Work RL Design]
[3]
[7]
[13]
[29]
[30]
[31]
[32]
Frequency Band (MHz)
-10 dB
Substrate
Average
Fractional
Dielectric
Antenna
bandwidth
Constant (r)
Gain (dBi)
Physical Substrate Size (Length × Width × height (mm3))
Electrical Antenna Largest Dimension (in terms of free space wavelength) at Mid frequency
1.06 – 1.28
18 %
1.4 – 1.62
14.5 %
1.9 – 2.3
19 %
3.5
52%
1.15-1.127
10%
-3.1
28 %
1.7-1.85
8.5%
2.2-2.7
20 %
3.4
56%
2.14–2.52
16.3 %
2.4
23.3 %
2.82–3.74
28 %
5.15–6.02
15.6 %
2.95
55.8%
2.25–2.85
23.5 %
2.3
12.7%
3.4–4.15
3.775
4.45–8
6.225
3.15
31.2
2.5- 2.7
7.7 %
0
30.4 %
3.3 - 3.8
14.1 %
5.3 - 5.9
10.7 %
2.7
65.2 %
2.36 - 2.57
8.4 %
-2
32.9 %
3.05 - 3.62
17.62 %
5.26 - 5.86
10.81 %
-1.2
70.1 %
1.74 - 1.81
3.08 %
-0.15
11.8%
4.2 - 5
15.17 %
5.7 - 6.6
8.33 %
3.5
41 %
0.9 - 0.93
3.27 %
2.8
29.05 %
1.22-1.23
0.8 %
1.65-2.6
44.7 %
3.2
67.5 %
2.35-2.58
9.33 %
-0.3
33.05 %
3.25-4
20.7 %
4.95-5.9
17.5 %
-1.2 4.4
4.4
4.4
4.4
4.4
4.4
2.2
2.33
4.4
1.9
1.2
2.35
2.8
1.6
-2.1
2.2
3.1
0.9 3.6
29 % 75 × 75 × 1.6
60 × 70 × 1.6
30 × 20 × 1.6
15 × 15 × 1.6
35 × 32 × 1.6
15 × 40 × 0.8
20 × 20 × 0.508
95 × 56 × 1.57
40 × 40 × 0.8
37 %
41 %
32.8 %
21.2 %
41.4 %
44.4 %
30.8 %
38.9 %
48.36 % 72.5 %
IV.
Conclusion
A new version of Π-section CRLH unit cell has been introduce to load a planar dipole antenna. Two different versions of CRLH unit cells are employed to design two different triple band antennas with with smaller physical size and or with lower operating frequencies compared to the reference dipole antenna. The two antennas preserve good gain with small antenna size compared to reference dipole antenna and most recent triple band antennas. Theoretical concepts, design and dispersion analysis are discussed for the reported new cell. Results validated using full wave simulation and experimental measurement for all reported antennas. The reported antennas can serve effectively with GPS, UMTS and WiFi applications.
REFERENCES [1] K. L. Wong, Compact and Broadband Microstrip Antennas. John Wiley & Sons, Inc., 2002. [2] C. P. Deng, X. Y. Liu, Z. K. Zhang, M.M. Tentzeris, "A Miniascape-Like Triple-Band Monopole Antenna for WBAN Applications", IEEE Ant. & Wire. Prop. Lett., vol. 11, 2012, pp. 1330 – 1333. [3] W. C. Liu, C. M. Wu, Y. Dai, "Design of Triple-Frequency Microstrip-Fed Monopole Antenna Using Defected Ground Structure", IEEE Trans. Ant. & Prop. vol. 59, no. 7, 2011, pp. 2457 - 2463. [4] P. Moeikham, C. Mahatthanajatuphat, P. Akkaraekthalin, "A triple band printed monopole antenna for WLAN/WiMAX applications", 2012 Int. Symposium on Antennas and Propagation (ISAP), pp. 295 – 298. [5] A. Mehdipour, A. Sebak, C Trueman, T. Denidni, "Compact Multiband Planar Antenna for 2.4/3.5/5.2/5.8-GHz Wireless Applications", IEEE Ant. & Wire. Prop. Lett. vol. 11, 2012 , pp. 144-147. [6] A. Kunwar, A. K. Gautam, K. Rambabu, "Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications", AEU - International Journal of Electronics and Communications, vol. 71, no. 1, 2017, pp. 82-88. [7] -M. Moosazadeh, S. Kharkovsky, "Compact and Small Planar Monopole Antenna With Symmetrical L- and U-Shaped Slots for WLAN/WiMAX Applications", IEEE Ant. & Wire. Prop. Lett., vol.13, 2014, pp. 388–391. [8] C. Chen, C. Sim, F. Chen, "A Novel Compact Quad-Band Narrow Strip-Loaded Printed Monopole Antenna", IEEE Ant. & Wire. Prop. Lett., vol. 8, 2009, pp. 974-976. [9] P. Beigi, and P. Mohammadi. "A novel small triple-band monopole antenna with crinkle fractal-structure."AEU-International Journal of Electronics and Communications, vol.70, no. 10, 2016, pp. 1382-1387.
[10] C. Caloz and T. Itoh, Electromagnetic Metamaterials Transmission Line Theory and Microwave Applications.: John Wiey & Sons, 2006. [11] G. V. Eleftheriades and K. G. Balmain, Negative Refractive Metamaterials. New Jersey: John Wiey & Sons, 2005. [12] M. A. Abdalla, M. Fouad, A. Ahmed, and Z. Hu, "A New Compact Microstrip Triple Band Antenna Using Half Mode CRLH Transmission Line" 2013 IEEE AP-S Int. Ant. & Prop. Symp., USA, pp. 634-635. [13] M. Abdalla, Z. Hu, & C. Muvianto, "Analysis and design of a triple band metamaterial simplified CRLH cells loaded monopole antenna", International Journal of Microwave and Wireless Technologies,vol.9, no. 4, 2017, pp. 903-913. [14] J. Saeid, M. A. Antoniades, J. Nourinia, and M. N. Azarmanesh. "A directivity-banddependent triple-band and wideband dual-polarized monopole antenna loaded with a viafree CRLH unit cell", IEEE Ant. & Wire. Prop. Lett., vol. 14, 2015, pp. 855-858. [15] M. Alibakhshi-Kenari and M. Naser-Moghadasi. "Novel UWB miniaturized integrated antenna based on CRLH metamaterial transmission lines."AEU-International Journal of Electronics and Communications, vol. 69, no. 8, 2015, pp. 1143-1149. [16] A. Locatelli, A. Capobianco, S. Boscolo, D. Modotto, M. Midrio, and C. Angelis. "Low-profile CRLH omnidirectional loop antenna for mobile wireless communications." 42nd European Microwave Conference (EuMC), pp. 401-403., 2012. [17] A. R Raslan, A. A. Ibrahim, and A. M. Safwat. "Resonant-type antennas loaded with CRLH unit cell", IEEE Ant. & Wire. Prop. Lett., vol. 12, 2013: 23-26. [18] Q. T. Óscar, E. Pucci, and E. R. Iglesias. "Compact loaded PIFA for multi frequency applications" IEEE Trans. Ant. & Prop. vol. 58, no. 3, 2010, pp. 656-664 [19] M. A. Abdalla, and A. A. Abdel Aziz, and Z. Hu, "High Selective Metamaterial Epsilon Negative Loaded E Antenna"", 2016 IEEE AP-S Int. Ant. & Prop. Symp. Digest, USA, pp. 1733-1734. [20] K. Saurav, D Sarkar, K. V. Srivastava, "CRLH Unit-Cell Loaded Multiband Printed Dipole Antenna", IEEE Ant. & Wire. Prop. Lett., vol. 13, 2014, pp. 852 – 855, 2014. [21] M. Abdalla, M. Abo El-Dahab, M. Ghouz, "Dual/Triple Band Printed Dipole Antenna Loaded With CRLH Cells", 2014 IEEE AP-S Int, Ant. & Prop. Symp., 2014, USA, pp. 1007-1008. [22] M. Abdalla, M. Abo El-Dahab, M. GHouz, "SIR Double Periodic CRLH Loaded Dipole Antenna", 2015 IEEE AP-S Int. Ant. & Prop. Symp., Canada, pp. 832-833. [23] J. Zhu, M. A. Antoniades, and G. V. Eleftheriades, “A compact tri-band monopole antenna with single-cell metamaterial loading,” IEEE Trans. Ant. & Prop., vol. 58, no. 4, 2010, pp. 1031–1038. [24] A. Erentok, and R. W. Ziolkowski. "Metamaterial-inspired efficient electrically small antennas." IEEE Trans. on Ant. & Prop., vol. 56, no. 3, 2008, pp. 691-707.
[25] M. A. Abdalla, W. W. Wahba, and A. M. Allam. "Asymmetric dual-band integrated compact CRLH SIW array antenna."Journal of Electromagnetic Waves and Applications, vol.31, no. 3, 2017, pp. 284-296 [26] M. A. Abdalla, M. A. Fouad, "CPW Dual Band Antenna Based on Asymmetric Generalized Metamaterial NRI Transmission Line for Ultra Compact Applications", Progress in Electromagnetic Research C, vol. 62, pp. 99-107, 2016. [27] M. A. Abdalla, "A High Selective Filtering Small Size/Dual Band Antenna using Hybrid Terminated Modified CRLH Cell”, Microwave and Optical Technology Letters, vol. 59, no. 7, 2017, pp. 1680-1686. [28]
D. M. Pozar, "Microwave Engineering 4th Ed." Wiely & Sons, 2012.
[29] Y.K. Park, D. Kang and Y. Sung, "Compact Folded Triband Monopole Antenna for USB Dongle Applications", IEEE Antennas and Wireless Propagation Letters, vol. 11, 2012, pp. 228 - 231. [30] N. Amani, M. Kamyab, A. Jafargholi, A. Hosseinbeig and J. S. Meiguni, "Compact tri-band metamaterial-inspired antenna based on CRLH resonant structures.", Electronics Letters, vol. 50, no. 12, 2014, pp. 847-848. [31] Ibrahim A. A., Safwat A. M. E., "Microstrip-Fed Monopole Antennas Loaded With CRLH Unit Cells", IEEE Trans. on Ant. & Prop., vol. 60 , no. 9, 2012, pp. 4027 - 4036. [32] X. L. Sun, J. Zhang, S. W. Cheung, T. I. Yuk, "A triple-band monopole antenna for WLAN and WiMAX applications", 2012 IEEE Antennas and Propagation Society International Symposium (APSURSI), pp. 1-2, USA, 2012.
S1434-8411(16)31503-5 http://dx.doi.org/10.1016/j.aeue.2017.06.029 AEUE 51947
To appear in:
International Journal of Electronics and Communications
Received Date: Revised Date: Accepted Date:
16 December 2016 18 June 2017 25 June 2017
Please cite this article as: M.A. Abdalla, M.H. Ghouz, M. Abo El-Dahab, Loaded Dipole Antennas with New CRLH Cell Configuration, International Journal of Electronics and Communications (2017), doi: http://dx.doi.org/ 10.1016/j.aeue.2017.06.029
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Loaded Dipole Antennas with New CRLH Cell Configuration Mahmoud A. Abdalla1, Mohamed H. Ghouz2, and Mohamed Abo El-Dahab2 1,
Electromagnetic Waves Group, Department of Electronic Engineering, Military Technical College, Cairo, Egypt.
2
Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Cairo, Egypt 1
[email protected]
In this paper, two different triple band dipole antennas loaded by new modified composite right left handed cell are presented. The modified cell can introduce large electrical length in small size. Thus, the two antennas are designed with smaller operating frequency or reduced physical length compared to a single frequency reference dipole. The designed antennas can serve different wireless services for GPS (1.27 GHz and 1.55 GHz), UMTS (1.85 GHz), and WiFi (2.4 GHz) in triple band functionalities. The lower operating frequency antenna size is (70 70 mm2) whereas the reduced physical length antenna size is (60 70 mm2). At mid band frequencies the reduced frequency antenna length is (0.29 0, 0.37 0, and 0.52 0), whereas that of the reduced physical length is (0.28 0, 0.41 0, and 0.56 0), at triple band mid frequency, respectively. Compared to a typical dipole antenna, the designed loaded dipoles can achieve a length reduction that can reach up to 50%. Moreover, the antenna has good gain at the triple bands (-1.2 dB, 1.9 dB and 3.5 dB for reduced operating frequency antenna and -3.1 dB, 1.2 dB and 3.4 dB for the reduced length antenna. The two antennas have good radiation efficiency that can reach up to 84% on a low cost antenna substrate. The mathematical analysis, full wave simulation and experimental measurements of the reported antennas are introduced. Keywords: Metamaterial, Composite right/left-handed (CRLH), Printed dipole antenna, Multi-band antennas. Corresponding author: Assoc. Prof. Mahmoud A. Abdalla, email: [email protected]
I.
INTRODUCTION
With the continuous development of mobile wireless service, there is a need for devices that integrate all these services. Also, the customer requirements of compact handheld devices have forced the front end engineers and researchers to introduce new techniques in design microwave components and antennas. As a contribution of the antenna design, a multi band antenna with good gain and omnidirectional radiation pattern has become a recent high challenge [1]. In designing planar multi band antennas, different techniques have been suggested by researchers. These techniques can be summarized as either using (1) separate resonators [2],[3], using incorporated resonators [4]-[6], loading a monopole/dipole with additive resonance circuits [7],[8] and by using fractal shapes [9]. The trade off in these techniques is the design flexibility for arbitrary functioning frequencies, almost unchanged
omni directional pattern and off course small antenna sizes. In order to contribute in this trade off challenge, it has been suggested over recent few years to load conventional resonant antennas with novel metamaterial (MTM) structures. The metamaterial structure, which was first suggested by Veslago can introduce artificially engineer constitutive parameters and hence phase propagation coefficient which can be designed to be arbitrary. Composite right left handed [10] or negative refractive index [11], are suggested as having negative electric permittivity and magnetic permeability. Propagation through these structures has two modes of operation; left handed mode characterized with negative phase propagation constant and right handed mode characterized with positive one. These characteristics have been employed to change the electrical length of many resonant antennas (e.g. monopole/dipole and loop). Accordingly, compact wide band / multi band loaded monopole antenna [12]-[15], loop antenna [16] inverted F antenna [17], [18] and E antenna [19] have been suggested. Also, some attempts for metamaterial loaded dipole antennas have been also suggested [20]-[23]. Also, these structures have achieved multi / band small antennas, but most of these antennas have small gain [24]-[27]. However, achieving triple band functionality with good gain is not discussed in literature, up to the author's knowledge. In this paper, we suggested a modified CRLH to load a dipole antenna to design a good gain triple band antenna. The modified cell is realized in Π-Section CRLH configuration with virtual ground. Thanks to this cell, up to 50 % size reduction in physical length of the dipole arm or the operating resonant frequency, compared to conventional dipole, can be achieved. This two features will be introduced in two designs identified as (RL Design) and (RF Design), respectively. The antennas are designed to function at the following services: Wi-Fi (2.4 GHz), Digital cellular service (DCS) (1710-1880 MHz) and GPS (1.227 GHz, 1.57 GHz) bands. Through the paper, the full wave simulation was done employing the commercial software Electronics Desktop (HFSS) from ANSYS.
II.
Multi Band CRLH Dipole Loaded Antenna Concept
The CRLH loaded dipole antenna is constructed by loading the dipole arm with Π-section CRLH cell. Hence, the total electrical length of the dipole arm will be equivalent to its linear unloaded physical section and the non-linear one over the CRLH cell. For achieving good gain, the CRLH cell position was chosen to be at the edges of the dipole arm. The mathematical expression of this principle is expressed as
Total Dipole CRLHcells n , n 0, 1 2,...
(1)
where Dipole is the phase shift along the two dipole arms (positive), CRLHcells is the phase shift of the loading cells (arbitrary positive/negative/zero) and hence Tot is the total loaded dipole phase shift. The more the condition in (1) is satisfied, the possible resonance and hence an antenna band functionality are achieved. To obtain triple band dipole operation, the dipole resonance condition in (1) is satisfied with n = -1, 0 and 1 as will be verified later. The suggested Π-Section loading CRLH cell configuration is shown in Fig. 1 (a). It is formed by cascading a series interdigital capacitor (Cse) and two shunt meander line inductors (Lsh) whereas the elements (Lse and Csh) are the cell parasitic elements. The dispersion propagation (The guided propagation phase constant (β) variation against frequency) along this cell can be explained by applying the periodic analysis of microwave network over a periodic distance (d). In details, this can be found by finding the ABCD matrix of the unit cell and applying propagation condition (cos (d)=A) as explained in [28]. Hence, the dispersion equation can be written as cos d 1 ZY
(2)
where Z j Lse 1/ jCse
Y jCsh 1/ j Lsh
Fig. 1. cell
(3-a) (3-b)
(a) Π-Section CRLH cell equivalent circuit, (b) The topology of Π-Section CRLH
The reference printed dipole antenna was designed to operate at 2.4 GHz. Since the dipole is unloaded, then its length was calculated in (1) such that CRLHcells = 0 and Total = . The 2D layout of the reference dipole is shown in Fig. 2 (a). The dipole antenna is fed by a 50 SMA
connector. A balun between the feeding microstrip line and the dipole arms has been employed to have balanced feeding and matching the antenna to 50 . The reference dipole, and all proposed dipoles in our paper, are printed on a low cost FR4 substrate with thickness h=1.6 mm, dielectric constant r = 4.4 and loss tangent =0.025. All dimensions are tabulated and presented in Table I. The simulated current distribution along the dipole at 2.4 GHz is shown in Fig. 2 (b). As shown in the figure, near the edges, the current is minimum (poor radiating parts). So the designed Π-CRLH cell length was desired to be realized in no more than 9 mm starting from the dipole arm open circuit side. This should ensure the reasonable antenna gain at the resonance frequencies as mentioned above.
Fig. 2. (a) Reference printed dipole antenna geometry, (b) The Current distribution along the reference dipole antenna
III.
Triple Band Dipole Antennas
The design procedures and results of the RF design and RL design are discussed in this section. The fabricated RF Design dipole antenna is shown in Fig. 3 (a) whereas the RL Design is shown in Fig. 3 (b).
A)
Π-Section CRLH cell Triple Band Dipole Loaded Antenna (Increase Elec.
Length (RF-Design)) In this section, the concept of Π-Section loading CRLH is used to increase the electrical length of the dipole while maintaining the same physical length of the conventional dipole. Our main challenge was to realize a cell that fulfills the equivalent circuit of the explained ΠSection CRLH and at the same time does not occupy large size of the dipole size to maintain high gain as well. So we have used a dual vertical back to back cell which is shown in Fig. 2
(b). It can be observed that an interdigital capacitor is employed as C se whereas the shunt inductor Lsh is realized using meandered line strips with virtual ground on the substrate bottom. The elements (Lse and Csh) are parasitic elements exist in the cell. All dimensions are tabulated in Table I. TABLE I: The Used Parameters Values for the, reference dipole, RF Design and RL Design Dipole Antennas
Par.
Ref. Printed Dipole
RF Design Dipole (Π -CRLH Cell with increased Electrical Length
RL Design Dipole (Π- CRLH Cell with reduced size)
Ws
75
75
60
Ls
75
75
70
Wd
7.5
7.5
5
Ld
55
55
40
gap
0.6
0.6
0.6
Wf
3
3
3
Lf
23
23
28
Wcp
9.7
9.7
7.2
Lg
15
15
10
La
36
36
36
Wng
--
0.3
0.3
Lng
--
4.3
4.3
S
--
0.5
0.5
L
--
7
6
Wl
--
0.6
0.6
Lm1
--
1
1
Lm2
--
4
4
Lm3
--
0.75
0.5
All design parameters are in mm
Fig. 3. Fabricated Π-Section CRLH loaded dipole antennas (a) Increased Electric Length (RF Design) (b) Reduced Length / Size ( RL Design)
The triple band loaded dipole has the same arm length (55 mm) as the reference dipole antenna (functions at 2.4 GHz) but its triple bands were adjusted to be at 1.27 GHz, 1.55 GHz and 1.9 GHz. This was achieved by employing the Π-CRLH cell as follow. (1) According to the current distribution over the dipole (shown in Fig. 2(b)), the cell should occupy no more than 9 mm at the two dipole ends. (2) Based on the remaining conventional dipole length remaining un-loaded (37 mm), the cell was designed to have a positive phase shift which is approximately 30o at 1.9 GHz. Hence, the zero phase shift; the transition between left and right handed pass bands was designed to be as initial value at 1.7 GHz. (3) To achieve a second band at 1.55 GHz, a total zero phase at this length had to be achieved; Thus, the ΠSection CRLH cell should achieve a left handed phase equals to -33o at 1.55 GHz. (4) To achieve a third band at 1.27 GHz, an –180o phase at this length had to be achieved, corresponding to n=-1 in (1). Based on that the Π-CRLH cell should achieve a left handed phase equals to -105o at 1.27 GHz. (5) In order to achieve good matching properties at the triple bands the cut off frequencies of left handed pass band and right handed pass band were chosen to be 1 GHz and 3 GHz, respectively. However, it is worth mentioning that some variations of these values were changed in the realization stage and some fine optimization tuning was applied. These requirements are satisfied by the following design equations as
fcl
f ch
1 4
1
1e9
LL CL
1
1
LR C R
(4-a) 3e 9
(4-b)
LL CR LR CL
d a cos1 1 ZY
1.7e
9
(4-c) 0o
d a cos1 1 ZY
1.9e
d a cos1 1 ZY
1.5e
d a cos1 1 ZY
1.2e
9
9
9
(4-d) 30o 33o
105o
(4-e) (4-f) (4-g)
Since the degree of freedom we have is four, so equations (4-a)-(4-d) were used whereas (4e)-(4-g) were satisfied in layout simulation stage. Based on the designed values, the detailed realization for the topology in Fig. 1 (b) was done. To confirm the designed values and the layout before loading it in the dipole, the dispersion analysis over the designed cell in Fig. 1 (b) had to be studied and compared with design objectives in (4). Accordingly, the cell topology in Fig. 1 (b) has been simulated in HFSS as a two port network. The validation has been done in the next explanation using two different techniques for further validation. First, in Fig. (4-a), the dispersion diagram based on the HFSS simulated scattering parameters (magnitudes and phase) using (5) 1 S11S22 S12 S21 d cos 1 2S21
(5)
It can be observed that the zero phase is achieved at 1.7 GHz and LH and RH pass bands cut off frequencies are (1 GHz and 3.1 GHz), close to designed values equations (4-a) and (4-b). Since the dispersion analysis requires an infinite structure, which is not our case, thus, exact phase shift values for only one cell. Therefore, the phase and magnitude of the transmission coefficient (S21) for the simulated cell are plotted in Fig. 4 (b). It is worth to comment that in typical condition, the passband dispersion diagram in Fig. 4 (a) should have the same message has been obtained from phase of S21 (only within the passband that is identified with magnitude of S21 close to 0 dB). In Fig. 4 (b), it can be observed that zero phase frequency is 1.7 GHz. The LH and RH cut off frequencies are 1.1 GHz and 3.2 GHz, respectively.
Comparing these values to those in Fig. 4 (a), we can observe a little shift in frequencies due to the ideal conditions in Fig. 4 (a). Also, we can observe that cut off frequencies in both Fig. 4(a) and Fig. 4 (b) are slightly shifted from the design objectives in (4). The shifts are due to the effect of the elements that can not be totally imposed in the design equations. However, these values still can meet the desired triple band frequencies at (1.27 GHz, 1.55 GHz and 1.9 GHz).
Fig. 4. The Π-Section CRLH cell employed in RF-Design (a) The dispersion diagram (b) The transmission coefficient (magnitude and phase)
The designed Π-CRLH cell was then loading the dipole arms. The simulated and measured reflection coefficient of the loaded dipole is shown in Fig. 5. It is obvious that the antenna’s reference resonance has been shifted from 2.4 GHz to 1.9 GHz and two new resonances have been introduced at 1.27 GHz and 1.55 GHz Therefore, we can claim that the Π-CRLH cell contributes to the dipole phase and satisfy (1) at n = 1 at f= 1.9 GHz whereas LH band adds leading to another band at n= 0 generating another resonance at 1.55 GHz. and at n=-1 generating resonance at 1.27 GHz.
Fig. 5. The simulated and measured reflection coefficient of increased length triple band laded Π section CRLH dipole antenna (RF Design)
B)
Π-Section CRLH cell Triple Band loaded Antenna (Reduce Antenna Size
RL-Design) In this section, a Π-Section CRLH loading cell is used to reduce the physical length while having the same electrical length. This second introduced loaded dipole antenna has the same reference dipole antenna frequency (2.4 GHz) but its single arm length (40 mm) is reduced with 25 % and introduced another frequencies at 1.25 GHz and 1.8 GHz. Design dimensions are tabulated in Table I as RL-Design. Similarly, the design have been carried out as explained above, with some optimization in the full wave simulation stage. The simulated and measured reflection coefficients of the RL-design loaded antenna compared to the reference antenna is shown in Fig. 6 with good agreements between results. Finally, a comparison between the proposed antennas are summarized in Table II. The comparison demonstrates competitive features in terms of its compact size and good gain.
Fig. 6. The simulated and measured reflection coefficient of decreased physical length triple band loaded Π-CRLH dipole antenna (RL Design).
TABLE II A summary of the Deigned Antennas Parameters (RF-Design and RL-Design) Antenna Service Frequency (GHz)
RL-Design
1.27 GHz, 1.57
1.25 GHz, 1.8 GHz
GHz and 1.9 GHz
and 2.4 GHz
18, 14.5 & 19
10, 8.5 and 20
-1.2, 1.9 and 3.5
-3.1, 1.2 and 3.4
65, 76 and 80
42, 60 and 84
Substrate (r) / thickness (mm)
4.4/1.6
4.4/1.6
Physical Substrate Size (mm mm)
75 75
60 70
-10 dB Fractional bandwidth (%) Gain (dB) Efficiency (%)
C)
RF-Design
Radiation Properties of Triple Band Antennas
The simulated normalized E/H radiation patterns of the two dipole loaded antennas (RFDesign / RL-Design) are shown in Fig. 7 (a)–(f) at the triple band operating frequencies. It obvious that the radiation patterns at all cases are like Omni-directional (directive in E plane
(=0o) and isotropic in H plane (=90o)). In other words, the patterns resemble the conventional dipole antenna pattern. This also can be confirmed by investigating the 3D simulated gain patterns at operating frequencies. The simulated gain values of the antennas in this work were calculated where they vary from -3 dB to 3.4 dB. Also, the simulated efficacy was calculated and it vary from 68% to 83%. These results confirm that the proposed loading succeed in achieving good gain and triple band functionality which is quiet good for a wireless applications.
Fig. 7. Simulated and measured radiation patters of triple band laded Π section CRLH dipole antenna (RF-Design (a-c) and RL-Design (d-f)).
Finally, a comparison between the introduced antenna and recent triple band compact size antenna are summarized in Table III. As we can observe that the table that the proposed antenna has good competitive parameters compared to recent published work. Also, it is worth to comment that the proposed antenna has suitable bandwidth for wireless services which is neither too large to suffer interference nor too narrow to affect the service.
Table III: A comparison between triple band antennas (recent published and the loaded dipole antenna in this work)
Reference
[This Work RF Design]
[This Work RL Design]
[3]
[7]
[13]
[29]
[30]
[31]
[32]
Frequency Band (MHz)
-10 dB
Substrate
Average
Fractional
Dielectric
Antenna
bandwidth
Constant (r)
Gain (dBi)
Physical Substrate Size (Length × Width × height (mm3))
Electrical Antenna Largest Dimension (in terms of free space wavelength) at Mid frequency
1.06 – 1.28
18 %
1.4 – 1.62
14.5 %
1.9 – 2.3
19 %
3.5
52%
1.15-1.127
10%
-3.1
28 %
1.7-1.85
8.5%
2.2-2.7
20 %
3.4
56%
2.14–2.52
16.3 %
2.4
23.3 %
2.82–3.74
28 %
5.15–6.02
15.6 %
2.95
55.8%
2.25–2.85
23.5 %
2.3
12.7%
3.4–4.15
3.775
4.45–8
6.225
3.15
31.2
2.5- 2.7
7.7 %
0
30.4 %
3.3 - 3.8
14.1 %
5.3 - 5.9
10.7 %
2.7
65.2 %
2.36 - 2.57
8.4 %
-2
32.9 %
3.05 - 3.62
17.62 %
5.26 - 5.86
10.81 %
-1.2
70.1 %
1.74 - 1.81
3.08 %
-0.15
11.8%
4.2 - 5
15.17 %
5.7 - 6.6
8.33 %
3.5
41 %
0.9 - 0.93
3.27 %
2.8
29.05 %
1.22-1.23
0.8 %
1.65-2.6
44.7 %
3.2
67.5 %
2.35-2.58
9.33 %
-0.3
33.05 %
3.25-4
20.7 %
4.95-5.9
17.5 %
-1.2 4.4
4.4
4.4
4.4
4.4
4.4
2.2
2.33
4.4
1.9
1.2
2.35
2.8
1.6
-2.1
2.2
3.1
0.9 3.6
29 % 75 × 75 × 1.6
60 × 70 × 1.6
30 × 20 × 1.6
15 × 15 × 1.6
35 × 32 × 1.6
15 × 40 × 0.8
20 × 20 × 0.508
95 × 56 × 1.57
40 × 40 × 0.8
37 %
41 %
32.8 %
21.2 %
41.4 %
44.4 %
30.8 %
38.9 %
48.36 % 72.5 %
IV.
Conclusion
A new version of Π-section CRLH unit cell has been introduce to load a planar dipole antenna. Two different versions of CRLH unit cells are employed to design two different triple band antennas with with smaller physical size and or with lower operating frequencies compared to the reference dipole antenna. The two antennas preserve good gain with small antenna size compared to reference dipole antenna and most recent triple band antennas. Theoretical concepts, design and dispersion analysis are discussed for the reported new cell. Results validated using full wave simulation and experimental measurement for all reported antennas. The reported antennas can serve effectively with GPS, UMTS and WiFi applications.
REFERENCES [1] K. L. Wong, Compact and Broadband Microstrip Antennas. John Wiley & Sons, Inc., 2002. [2] C. P. Deng, X. Y. Liu, Z. K. Zhang, M.M. Tentzeris, "A Miniascape-Like Triple-Band Monopole Antenna for WBAN Applications", IEEE Ant. & Wire. Prop. Lett., vol. 11, 2012, pp. 1330 – 1333. [3] W. C. Liu, C. M. Wu, Y. Dai, "Design of Triple-Frequency Microstrip-Fed Monopole Antenna Using Defected Ground Structure", IEEE Trans. Ant. & Prop. vol. 59, no. 7, 2011, pp. 2457 - 2463. [4] P. Moeikham, C. Mahatthanajatuphat, P. Akkaraekthalin, "A triple band printed monopole antenna for WLAN/WiMAX applications", 2012 Int. Symposium on Antennas and Propagation (ISAP), pp. 295 – 298. [5] A. Mehdipour, A. Sebak, C Trueman, T. Denidni, "Compact Multiband Planar Antenna for 2.4/3.5/5.2/5.8-GHz Wireless Applications", IEEE Ant. & Wire. Prop. Lett. vol. 11, 2012 , pp. 144-147. [6] A. Kunwar, A. K. Gautam, K. Rambabu, "Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications", AEU - International Journal of Electronics and Communications, vol. 71, no. 1, 2017, pp. 82-88. [7] -M. Moosazadeh, S. Kharkovsky, "Compact and Small Planar Monopole Antenna With Symmetrical L- and U-Shaped Slots for WLAN/WiMAX Applications", IEEE Ant. & Wire. Prop. Lett., vol.13, 2014, pp. 388–391. [8] C. Chen, C. Sim, F. Chen, "A Novel Compact Quad-Band Narrow Strip-Loaded Printed Monopole Antenna", IEEE Ant. & Wire. Prop. Lett., vol. 8, 2009, pp. 974-976. [9] P. Beigi, and P. Mohammadi. "A novel small triple-band monopole antenna with crinkle fractal-structure."AEU-International Journal of Electronics and Communications, vol.70, no. 10, 2016, pp. 1382-1387.
[10] C. Caloz and T. Itoh, Electromagnetic Metamaterials Transmission Line Theory and Microwave Applications.: John Wiey & Sons, 2006. [11] G. V. Eleftheriades and K. G. Balmain, Negative Refractive Metamaterials. New Jersey: John Wiey & Sons, 2005. [12] M. A. Abdalla, M. Fouad, A. Ahmed, and Z. Hu, "A New Compact Microstrip Triple Band Antenna Using Half Mode CRLH Transmission Line" 2013 IEEE AP-S Int. Ant. & Prop. Symp., USA, pp. 634-635. [13] M. Abdalla, Z. Hu, & C. Muvianto, "Analysis and design of a triple band metamaterial simplified CRLH cells loaded monopole antenna", International Journal of Microwave and Wireless Technologies,vol.9, no. 4, 2017, pp. 903-913. [14] J. Saeid, M. A. Antoniades, J. Nourinia, and M. N. Azarmanesh. "A directivity-banddependent triple-band and wideband dual-polarized monopole antenna loaded with a viafree CRLH unit cell", IEEE Ant. & Wire. Prop. Lett., vol. 14, 2015, pp. 855-858. [15] M. Alibakhshi-Kenari and M. Naser-Moghadasi. "Novel UWB miniaturized integrated antenna based on CRLH metamaterial transmission lines."AEU-International Journal of Electronics and Communications, vol. 69, no. 8, 2015, pp. 1143-1149. [16] A. Locatelli, A. Capobianco, S. Boscolo, D. Modotto, M. Midrio, and C. Angelis. "Low-profile CRLH omnidirectional loop antenna for mobile wireless communications." 42nd European Microwave Conference (EuMC), pp. 401-403., 2012. [17] A. R Raslan, A. A. Ibrahim, and A. M. Safwat. "Resonant-type antennas loaded with CRLH unit cell", IEEE Ant. & Wire. Prop. Lett., vol. 12, 2013: 23-26. [18] Q. T. Óscar, E. Pucci, and E. R. Iglesias. "Compact loaded PIFA for multi frequency applications" IEEE Trans. Ant. & Prop. vol. 58, no. 3, 2010, pp. 656-664 [19] M. A. Abdalla, and A. A. Abdel Aziz, and Z. Hu, "High Selective Metamaterial Epsilon Negative Loaded E Antenna"", 2016 IEEE AP-S Int. Ant. & Prop. Symp. Digest, USA, pp. 1733-1734. [20] K. Saurav, D Sarkar, K. V. Srivastava, "CRLH Unit-Cell Loaded Multiband Printed Dipole Antenna", IEEE Ant. & Wire. Prop. Lett., vol. 13, 2014, pp. 852 – 855, 2014. [21] M. Abdalla, M. Abo El-Dahab, M. Ghouz, "Dual/Triple Band Printed Dipole Antenna Loaded With CRLH Cells", 2014 IEEE AP-S Int, Ant. & Prop. Symp., 2014, USA, pp. 1007-1008. [22] M. Abdalla, M. Abo El-Dahab, M. GHouz, "SIR Double Periodic CRLH Loaded Dipole Antenna", 2015 IEEE AP-S Int. Ant. & Prop. Symp., Canada, pp. 832-833. [23] J. Zhu, M. A. Antoniades, and G. V. Eleftheriades, “A compact tri-band monopole antenna with single-cell metamaterial loading,” IEEE Trans. Ant. & Prop., vol. 58, no. 4, 2010, pp. 1031–1038. [24] A. Erentok, and R. W. Ziolkowski. "Metamaterial-inspired efficient electrically small antennas." IEEE Trans. on Ant. & Prop., vol. 56, no. 3, 2008, pp. 691-707.
[25] M. A. Abdalla, W. W. Wahba, and A. M. Allam. "Asymmetric dual-band integrated compact CRLH SIW array antenna."Journal of Electromagnetic Waves and Applications, vol.31, no. 3, 2017, pp. 284-296 [26] M. A. Abdalla, M. A. Fouad, "CPW Dual Band Antenna Based on Asymmetric Generalized Metamaterial NRI Transmission Line for Ultra Compact Applications", Progress in Electromagnetic Research C, vol. 62, pp. 99-107, 2016. [27] M. A. Abdalla, "A High Selective Filtering Small Size/Dual Band Antenna using Hybrid Terminated Modified CRLH Cell”, Microwave and Optical Technology Letters, vol. 59, no. 7, 2017, pp. 1680-1686. [28]
D. M. Pozar, "Microwave Engineering 4th Ed." Wiely & Sons, 2012.
[29] Y.K. Park, D. Kang and Y. Sung, "Compact Folded Triband Monopole Antenna for USB Dongle Applications", IEEE Antennas and Wireless Propagation Letters, vol. 11, 2012, pp. 228 - 231. [30] N. Amani, M. Kamyab, A. Jafargholi, A. Hosseinbeig and J. S. Meiguni, "Compact tri-band metamaterial-inspired antenna based on CRLH resonant structures.", Electronics Letters, vol. 50, no. 12, 2014, pp. 847-848. [31] Ibrahim A. A., Safwat A. M. E., "Microstrip-Fed Monopole Antennas Loaded With CRLH Unit Cells", IEEE Trans. on Ant. & Prop., vol. 60 , no. 9, 2012, pp. 4027 - 4036. [32] X. L. Sun, J. Zhang, S. W. Cheung, T. I. Yuk, "A triple-band monopole antenna for WLAN and WiMAX applications", 2012 IEEE Antennas and Propagation Society International Symposium (APSURSI), pp. 1-2, USA, 2012.