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E-shape Microstrip Antenna Backed By Pairs Of Slots Cut Ground Plane For Wideband Response
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Procedia Computer Science 00 (2018) 000–000
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Procedia Computer Science 143 (2018) 101–107
8th International Conference on Advances in Computing and Communication (ICACC-2018) 8th International Conference on Advances in Computing and Communication (ICACC-2018)
8th International Conference on Advances in Computing and Communication (ICACC-2018)
E-shape Microstrip Antenna Backed By Pairs Of Slots Cut Ground E-shape Microstrip Antenna Backed By Pairs Of Slots Cut Ground Plane For Wideband Response Plane For Wideband Response Amit A. Deshmukhaa*, Amita Mhatrebb, Chinmay Kudoobb, and Shefali Pawarbb Amit A. Deshmukh *, Amita Mhatre , Chinmay Kudoo , and Shefali Pawar a a
Professor and Head, EXTC Department, DJSCE, Vile – Parle (W), Mumbai, India b PG student, EXTC Department, DJSCE, Vile Vile – Parle (W),(W), Mumbai, IndiaIndia Professor and Head, EXTC Department, DJSCE, – Parle Mumbai, b PG student, EXTC Department, DJSCE, Vile – Parle (W), Mumbai, India
Abstract Abstract Wideband design of E-shape microstrip antenna is discussed, which yields bandwidth of 213 MHz (19.42%) on the substrate of enhancement E-shapeis antenna bandwidth is obtained by embedding pairs of rectangular on the thickness Wideband0.06 design of E-shape microstripinantenna discussed, which yields bandwidth of 213 MHz (19.42%) on the slots substrate of 0. Further ground plane. explaining the effect of slots on the resonant modes the patchpairs and modified ground plane, in Further study enhancement in E-shape antenna bandwidth is obtained by of embedding of rectangular slots on the thickness 0.06A0.detailed yieldingplane. wideband response, is presented. E-shape backed by single pair of cut ground plane yields BW of 233 ground A detailed study explaining The the effect of patch slots on the resonant modes of slots the patch and modified ground plane, in MHz (21.4%) whereas that with two pairs The of slots on the ground plane, (28.12%) is obtained, is yielding wideband response, is presented. E-shape patch backed by bandwidth single pair of 318 slotsMHz cut ground plane yields BWwhich of 233 nearly 10% more as compared to two the bandwidth obtained E-shape The antenna pairs ofisslots on thewhich ground MHz (21.4%) whereas that with pairs of slots on thefrom ground plane,patch. bandwidth of 318 with MHztwo (28.12%) obtained, is plane broadside radiationtopattern across theobtained complete bandwidth peak broadside more than 7 dBi.on the ground nearlyyields 10% more as compared the bandwidth from E-shapewith patch. The antenna gain with of two pairs of slots plane yields broadside radiation pattern across the complete bandwidth with peak broadside gain of more than 7 dBi. © 2018 The Authors. Published by Elsevier B.V. © 2018 The Authors. Published by Elsevier B.V. This is an open accessPublished article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) © 2018 The Authors. by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific of of thethe 8th8th International Conference on Advances in in This is an open access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee International Conference on Advances Computing and Communication Selection and peer-review under (ICACC-2018). responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018). Computing and Communication (ICACC-2018). Keywords: Broadband microstrip antenna; E-shape microstrip antenna; Defected ground plane; Pair of rectangular slots Keywords: Broadband microstrip antenna; E-shape microstrip antenna; Defected ground plane; Pair of rectangular slots
* Corresponding author. Tel.: +91 22 4233 5025; fax: +91 22 2619 4988. E-mail address:author. [email protected] * Corresponding Tel.: +91 22 4233 5025; fax: +91 22 2619 4988. E-mail address: [email protected] 1877-0509 © 2018 The Authors. Published by Elsevier B.V. This is an open access under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) 1877-0509 © 2018 Thearticle Authors. Published by Elsevier B.V. Selection under responsibility of the scientific of the 8th International Conference on Advances in Computing and This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Communication (ICACC-2018). Selection and peer-review under responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018).
1877-0509 © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018). 10.1016/j.procs.2018.10.357
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Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
1. Introduction Wideband response in microstrip antenna (MSA) has been commonly realized by embedding slot in the radiating patch [1, 2]. As the slot is reported to introduce additional mode nearer to the fundamental mode of the patch, MSA bandwidth (BW) is increased without increasing the patch size. While realizing wider BW, different slot shapes like, U-slot, half U-slot, V-slot and its modified variations, step U and half U-slots, pair of rectangular slots, bow-tie shape slots have been used [1 – 8]. Instead of cutting the slot on the radiating patch, MSA BW has been increased by embedding slots on the ground plane leading to the defected ground plane structure (DGS) [9, 10]. While introducing any modifications in the radiating patch or ground plane, an in-sight is needed that clearly highlights the effects of slots on patch resonant modes. This is essential as when dimensions of radiating patch are fixed, then resonant modes in the patch subject to the boundary conditions are fixed. Any modifications in antenna geometry will only result into the re-arrangements of these modes in terms of frequency and impedances. In wideband slot cut MSAs, detailed study explaining effects of slots on patch resonant modes, and design theory based on the supporting resonant length formulations is reported for wideband U-slot and E-shape MSAs [11 – 13]. But similar in-depth analysis is not much widely reported for wide band MSAs using DGS. In the proposed work here, wide band design of E-shape MSA backed by pairs of slots cut ground plane is presented. First design of E-shape MSA is discussed. In the E-shape patch, pair of slots alters the resonance frequency of second order orthogonal TM 02 mode, which along with TM10 mode realizes wider BW. On substrate thickness of 1.82 cm (0.0640), a BW of 213 MHz (19.42%) is obtained. Further enhancement in the BW of E-shape patch is obtained by using DGS structure in which pairs of slots were introduced on the ground plane. The first pair of slots in the ground plane reduces TM02 mode frequency of equivalent square shape ground plane to realize increased BW of 233 MHz (21.4%). Next second pair of slots on the ground plane tunes TM12 mode frequency on the ground plane which along with TM10 and TM02 modes on the patch and TM02 mode on the ground plane gives BW of 318 MHz (28.12%). Thus using two pairs of ground plane slots, an increment in BW by nearly 10% is obtained as compared to the E-shape patch. The proposed E-shape MSA backed by DGS shows broadside radiation pattern across the BW with peak gain of more than 7 dBi. In the reported work on broadband MSAs using DGS, similar wideband response has been reported, but they lack in providing detailed explanation about working of antenna in terms of patch and ground plane resonant modes. The proposed work here explains in detail about various modes present in wideband response, and this in-sight will be helpful in designing similar antenna at any given frequency. Thus original explanation for working of E-shape MSA backed by DGS is the novelty in the proposed work. The wideband E-shape antennas discussed here were first studied using IE3D software followed by experimentation. The measurements for optimum designs were carried out using high frequency instruments like, „ZVH – 8‟, „SMB 100A‟ and „FSC – 6‟, inside an Antenna Lab where minimum reflections from surrounding objects is present. In the above measurements, broadband and high gain Horn Antennas as a reference antennas were used. 2. E-shape MSA backed by Pairs of slots loaded Ground Plane The configuration of coaxially fed wideband E-shape MSA backed by square ground plane which is embedded with two pairs of rectangular slots is shown in Fig. 1(a, b). The dimensions of the patch and frequencies referred in the text and figures in the paper are in „cm‟ and „MHz‟, respectively. The proposed configuration is studied using three layer suspended configuration in which two layers of glass epoxy substrate (r = 4.3, h = 0.16 cm, tan = 0.02) are separated by an air gap of „ha‟. For total substrate thickness of 0.0640 („ha‟ = 1.6 cm) dimensions of equivalent square MSA (SMSA) (L) are calculated such that its TM10 mode frequency is around 1050 MHz. The SMSA side length (L) is found to be 10 cm. A finite square ground plane of length (Lg) 14 cm is selected. First to realize Eshape MSA, pair of slots of dimensions „Ls‟ and „ws‟ are cut on one of the radiating edge of SMSA as shown in Fig. 1(a). The slots tune the orthogonal TM02 mode frequency in SMSA with respect TM10 mode as shown in Fig. 1(c), to yield wider BW as shown in Fig. 1(d). For „Ls‟ = 6.0, „ws‟ = 0.4, and „xf‟ = 2.6 cm, simulated and measured BW in E-shape patch are 213 MHz (19.42%) and 205 MHz (19.03%). The E-shape patch exhibits broadside pattern over the BW with peak gain of above 7 dBi.
Amit A. Deshmukh al.Shefali / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, et and Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 1. (a) Top and (b) side views of E-shape MSA backed by pairs of slots cut ground plane; (c) resonance curve plots for varying „Ls‟; and (d) input impedance plots for equivalent E-shape MSA
To increase the BW in E-shape patch, first pair of slots of length and width „L1‟ and „W1‟ are cut on the ground plane which is below the other radiating edge of E-shape patch as shown in Fig. 1(a). To optimize for BW, parametric study for variation in length „L1‟ is carried out and resonance curve plots for the same are shown in Fig. 2(a). The structure of the MSA is similar to parallel plate capacitor where two plates represents the patch and ground plane. Hence any modifications in the ground plane will be linked to that on the patch through the fringing fields that exist between the two plates. Thus, only when the part of slot length „L1‟ lies below the patch, then only it will affect the current distributions on the E-shape patch. Hence in Fig. 2(a), only incremental overlapping slot length that lies below the E-shape patch is considered and thus plots are shown for „L1g‟ = 0, 1, 2 and 3 cm. For „L1g‟ increasing from 0 to 2 cm, not much variation in resonance curve plots is noted. However, for „L1g‟ = 3 cm, additional peak nearer to TM10 mode of the patch is seen. The surface current distributions at observed resonant modes for „L1g‟ = 3 cm is shown in Fig. 3(a – d). At first and third peak, current variations due to TM 10 and TM02
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modes on the patch are noted. At second peak current shows two half wavelength variations on the ground plane. This variation is due to TM02 mode on the square ground plane. To prove that this mode is due to the ground plane, coaxially fed square patch of length 14 cm is simulated for increasing slot length (E-shape patch) and its resonance curve plots are shown in Fig. 2(b, c).
Fig. 2. (a) Resonance curve plots for E-shape MSA backed by pair of slots cut ground plane for increasing „L1g‟; and (b, c) resonance curve plots for increasing slot length for E-shape MSA with patch length „Lg‟ = 14 cm
With increasing slot length, patch‟s TM02 and TM12 mode frequencies reduces. As observed from Fig. 2(c), for slot length of 5 cm (L1g = 3 cm), resonance peak due to modified TM 02 mode is formed nearer to the same frequency position as observed in Fig. 2(a). This modal variation supports that additional mode introduced in E-shape MSA backed by pair of slots ground plane is due to ground plane TM 02 mode. The optimum BW for this configuration is obtained for, „L1g‟ = 2.8, „w1‟ = 0.4, „y1‟ = 3.1 and „xf‟ = 2.6 cm as shown in Fig. 3(e). The simulated and measured BW‟s are, 233 MHz (21.4%) and 239 MHz (22.35%), respectively. As compared with E-shape patch, this DGS antenna yields additional 3% of BW. It shows broadside pattern over the VSWR BW with peak gain above 7 dBi. To further enhance the BW, second pair of slots is embedded on the opposite edge of the ground plane, as shown in Fig. 1(a). The resonance curve plots for increasing slot length „Lp‟ is shown in Fig. 3(f).
Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 3. (a – d) Surface current distributions at observed resonant modes for E-shape MSA backed by pair of slots ground plane for „L1g‟ = 3 cm; (e) input impedance plots for optimum design of E-shape MSA backed by pair of slots ground plane; (f) resonance curve plots for increasing slot length „Lp‟; (g) plots for equivalent SMSA with „Lg‟ = 14 cm with increasing slot lengths; and (h) optimum input impedance plots for wideband E-shape MSA backed by two pairs of slot lengths
With increasing length „Lp‟ additional resonant mode is observed at a frequency which is higher than TM10 mode frequency of the patch. The current distribution at this mode reveals that this is due to modified TM 12 mode on the
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ground plane. To support this, ground plane was separately simulated as a SMSA loaded with two pairs of slots on each of its radiating edge, i.e. „L1‟ and „Lp‟. The resonance curve plots for the same with „L1‟ = 5 cm and increasing „Lp‟ is shown in Fig. 3(g). It is observed that with second pair of slots, modified TM12 mode frequency of the patch reduces and for „Lp‟ = 3 cm, it is formed nearer to the same frequency location at which additional mode is observed for E-shape MSA backed by two pairs of slot cut ground plane. This confirms that additional mode here is the modified TM12, that increases the BW. The optimum response is obtained for „Lp‟ = 3, „wp‟ = 0.4 and „yp‟ = 4.0 cm as shown in Fig. 3(h). The simulated and measured BW‟s are 318 MHz (28.12%) and 322 MHz (28.83%), respectively. Thus as compared to E-shape MSA, two pairs of slot cut design yields 10% increment in the BW. Pattern and gain variation over the BW for this configuration is shown in Figs. 4(a – d) and 5(a), respectively. Across the BW, radiation pattern is broadside with E-plane directed along = 00. The peak broadside co-polar antenna gain is above 7 dBi. The fabricated prototype of the configuration is shown in Fig. 5(b, c).
Fig. 4. (a – d) Radiation pattern at two frequencies over the BW for E-shape MSA backed by two pairs of slots cut ground plane
In the proposed paper, wide band design of E-shape MSA using DGS is proposed which yields 10% additional BW as compared to the E-shape patch. In the reported papers, different configurations for wide band and multi-band response using DGS have been reported. However, in them an explanation about working of antenna in terms of patch resonant modes was not provided. Proposed work provides an original explanation for antenna working in terms of the resonant modes excited in patch and the ground plane. The similar work providing such detailed study is not available in the literature, and that is the novelty here. The proposed design is not targeted at any specific application but it provides systematic explanation for wideband behaviour of MSA backed by DGS structure.
Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 5. (a) Gain variation over BW and (b, c) fabricated prototype of E-shape MSA backed by two pairs of slots cut ground plane
3. Conclusions Wide band designs of E-shape MSA backed by pair of slots cut square ground plane is presented. The first pair of slot tunes TM02 mode frequency on the ground plane to yield more than 230 MHz (>21%) of BW, which is 3% more as compared to the E-shape patch. Addition of second pair of slots on the ground plane tunes next higher order TM12 mode frequency on the ground plane which yields more than 300 MHz (>28%) of BW, that is 10% additional BW against E-shape patch. The present works provides original explanation about working of antenna in terms resonant modes on patch and ground plane, which is not explained in detail in reported work. This is the novelty here. References [1] Wong, K. L. (2002) “Compact and Broadband Microstrip Antennas” John Wiley & sons, Inc., New York, USA. [2] Huynh, T., and Lee, K. F (1995) “Single-Layer Single-Patch Wideband Microstrip Antenna.” Electronics Letters 31 (16): 1310-1312. [3] Lee, K. F., Yang, S. L. S. et al. (2010) “The Versatile U-slot Patch.” IEEE Antennas & Propagation Magazine 52 (1): 71 – 88. [4] Kumar, G., and Ray, K. P. (2003) “Broadband Microstrip Antennas”, Artech House, USA [5] Wong, K. L., and Hsu, W. H. (2001) “A Broadband Rectangular Patch Antenna with a Pair of wide slits.” IEEE Transactions on Antennas & Propagation 49: 1345 – 1347. [6] Guo, Y. X., Luk, K. M. et al. (1999) “U-slot circular patch antennas with L-probe feeding.” Electronics Letters 35 (20): 1694 – 1695. [7] Tong, K. F., Luk, K. M. et al. (2000) “A Broadband U-slot Rectangular Patch Antenna on a Microwave Substrate.” IEEE Transactions on Antennas & Propagation 48 (6): 954 – 960. [8] Guo, Y. X., Luk, K. M. et al. (1998) “Double U-slot rectangular patch antenna.” Electronics Letters 34 (19): 1805 – 1806. [9] Chakraborty, Ujjal, Chowdhury, S. K. et al. (2013) “Frequency tuning and miniaturization of square microstrip antenna embedded with „„t‟‟shaped defected ground structure.” Microwave & Optical Technology Letters 55 (4): 869 – 872. [10] Wang, T., Yin, Y. Z. et al. (2012) “Compact triple-band antenna using de-fected ground structure for wlan/wimax applications.” Progress In Electromagnetics Research Letters 35: 155-164. [11] Deshmukh, Amit A., and Ray, K. P. (2013) “Analysis Of Broadband -shaped Microstrip Antennas. IEEE Antennas and Propagation Magazine 2013; 55 (2): 107– 123. [12] Deshmukh, Amit A., and Ray K. P. et al. (2012) “Analysis of slot cut Broadband and Dual band Rectangular Microstrip Antennas.” IETE Journal of Research; 59 (3): 193 – 200. [13] Deshmukh, Amit A., and Ray, K. P. (2017) “Analysis and Design of Broadband U-slot cut Rectangular Microstrip Antennas.” Sadhana – Academy Proceedings in Engineering Science, Springer Publication; 42 (10): 1671 – 1684,
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Procedia Computer Science 143 (2018) 101–107
8th International Conference on Advances in Computing and Communication (ICACC-2018) 8th International Conference on Advances in Computing and Communication (ICACC-2018)
8th International Conference on Advances in Computing and Communication (ICACC-2018)
E-shape Microstrip Antenna Backed By Pairs Of Slots Cut Ground E-shape Microstrip Antenna Backed By Pairs Of Slots Cut Ground Plane For Wideband Response Plane For Wideband Response Amit A. Deshmukhaa*, Amita Mhatrebb, Chinmay Kudoobb, and Shefali Pawarbb Amit A. Deshmukh *, Amita Mhatre , Chinmay Kudoo , and Shefali Pawar a a
Professor and Head, EXTC Department, DJSCE, Vile – Parle (W), Mumbai, India b PG student, EXTC Department, DJSCE, Vile Vile – Parle (W),(W), Mumbai, IndiaIndia Professor and Head, EXTC Department, DJSCE, – Parle Mumbai, b PG student, EXTC Department, DJSCE, Vile – Parle (W), Mumbai, India
Abstract Abstract Wideband design of E-shape microstrip antenna is discussed, which yields bandwidth of 213 MHz (19.42%) on the substrate of enhancement E-shapeis antenna bandwidth is obtained by embedding pairs of rectangular on the thickness Wideband0.06 design of E-shape microstripinantenna discussed, which yields bandwidth of 213 MHz (19.42%) on the slots substrate of 0. Further ground plane. explaining the effect of slots on the resonant modes the patchpairs and modified ground plane, in Further study enhancement in E-shape antenna bandwidth is obtained by of embedding of rectangular slots on the thickness 0.06A0.detailed yieldingplane. wideband response, is presented. E-shape backed by single pair of cut ground plane yields BW of 233 ground A detailed study explaining The the effect of patch slots on the resonant modes of slots the patch and modified ground plane, in MHz (21.4%) whereas that with two pairs The of slots on the ground plane, (28.12%) is obtained, is yielding wideband response, is presented. E-shape patch backed by bandwidth single pair of 318 slotsMHz cut ground plane yields BWwhich of 233 nearly 10% more as compared to two the bandwidth obtained E-shape The antenna pairs ofisslots on thewhich ground MHz (21.4%) whereas that with pairs of slots on thefrom ground plane,patch. bandwidth of 318 with MHztwo (28.12%) obtained, is plane broadside radiationtopattern across theobtained complete bandwidth peak broadside more than 7 dBi.on the ground nearlyyields 10% more as compared the bandwidth from E-shapewith patch. The antenna gain with of two pairs of slots plane yields broadside radiation pattern across the complete bandwidth with peak broadside gain of more than 7 dBi. © 2018 The Authors. Published by Elsevier B.V. © 2018 The Authors. Published by Elsevier B.V. This is an open accessPublished article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) © 2018 The Authors. by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific of of thethe 8th8th International Conference on Advances in in This is an open access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee International Conference on Advances Computing and Communication Selection and peer-review under (ICACC-2018). responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018). Computing and Communication (ICACC-2018). Keywords: Broadband microstrip antenna; E-shape microstrip antenna; Defected ground plane; Pair of rectangular slots Keywords: Broadband microstrip antenna; E-shape microstrip antenna; Defected ground plane; Pair of rectangular slots
* Corresponding author. Tel.: +91 22 4233 5025; fax: +91 22 2619 4988. E-mail address:author. [email protected] * Corresponding Tel.: +91 22 4233 5025; fax: +91 22 2619 4988. E-mail address: [email protected] 1877-0509 © 2018 The Authors. Published by Elsevier B.V. This is an open access under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) 1877-0509 © 2018 Thearticle Authors. Published by Elsevier B.V. Selection under responsibility of the scientific of the 8th International Conference on Advances in Computing and This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Communication (ICACC-2018). Selection and peer-review under responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018).
1877-0509 © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of the 8th International Conference on Advances in Computing and Communication (ICACC-2018). 10.1016/j.procs.2018.10.357
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Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
1. Introduction Wideband response in microstrip antenna (MSA) has been commonly realized by embedding slot in the radiating patch [1, 2]. As the slot is reported to introduce additional mode nearer to the fundamental mode of the patch, MSA bandwidth (BW) is increased without increasing the patch size. While realizing wider BW, different slot shapes like, U-slot, half U-slot, V-slot and its modified variations, step U and half U-slots, pair of rectangular slots, bow-tie shape slots have been used [1 – 8]. Instead of cutting the slot on the radiating patch, MSA BW has been increased by embedding slots on the ground plane leading to the defected ground plane structure (DGS) [9, 10]. While introducing any modifications in the radiating patch or ground plane, an in-sight is needed that clearly highlights the effects of slots on patch resonant modes. This is essential as when dimensions of radiating patch are fixed, then resonant modes in the patch subject to the boundary conditions are fixed. Any modifications in antenna geometry will only result into the re-arrangements of these modes in terms of frequency and impedances. In wideband slot cut MSAs, detailed study explaining effects of slots on patch resonant modes, and design theory based on the supporting resonant length formulations is reported for wideband U-slot and E-shape MSAs [11 – 13]. But similar in-depth analysis is not much widely reported for wide band MSAs using DGS. In the proposed work here, wide band design of E-shape MSA backed by pairs of slots cut ground plane is presented. First design of E-shape MSA is discussed. In the E-shape patch, pair of slots alters the resonance frequency of second order orthogonal TM 02 mode, which along with TM10 mode realizes wider BW. On substrate thickness of 1.82 cm (0.0640), a BW of 213 MHz (19.42%) is obtained. Further enhancement in the BW of E-shape patch is obtained by using DGS structure in which pairs of slots were introduced on the ground plane. The first pair of slots in the ground plane reduces TM02 mode frequency of equivalent square shape ground plane to realize increased BW of 233 MHz (21.4%). Next second pair of slots on the ground plane tunes TM12 mode frequency on the ground plane which along with TM10 and TM02 modes on the patch and TM02 mode on the ground plane gives BW of 318 MHz (28.12%). Thus using two pairs of ground plane slots, an increment in BW by nearly 10% is obtained as compared to the E-shape patch. The proposed E-shape MSA backed by DGS shows broadside radiation pattern across the BW with peak gain of more than 7 dBi. In the reported work on broadband MSAs using DGS, similar wideband response has been reported, but they lack in providing detailed explanation about working of antenna in terms of patch and ground plane resonant modes. The proposed work here explains in detail about various modes present in wideband response, and this in-sight will be helpful in designing similar antenna at any given frequency. Thus original explanation for working of E-shape MSA backed by DGS is the novelty in the proposed work. The wideband E-shape antennas discussed here were first studied using IE3D software followed by experimentation. The measurements for optimum designs were carried out using high frequency instruments like, „ZVH – 8‟, „SMB 100A‟ and „FSC – 6‟, inside an Antenna Lab where minimum reflections from surrounding objects is present. In the above measurements, broadband and high gain Horn Antennas as a reference antennas were used. 2. E-shape MSA backed by Pairs of slots loaded Ground Plane The configuration of coaxially fed wideband E-shape MSA backed by square ground plane which is embedded with two pairs of rectangular slots is shown in Fig. 1(a, b). The dimensions of the patch and frequencies referred in the text and figures in the paper are in „cm‟ and „MHz‟, respectively. The proposed configuration is studied using three layer suspended configuration in which two layers of glass epoxy substrate (r = 4.3, h = 0.16 cm, tan = 0.02) are separated by an air gap of „ha‟. For total substrate thickness of 0.0640 („ha‟ = 1.6 cm) dimensions of equivalent square MSA (SMSA) (L) are calculated such that its TM10 mode frequency is around 1050 MHz. The SMSA side length (L) is found to be 10 cm. A finite square ground plane of length (Lg) 14 cm is selected. First to realize Eshape MSA, pair of slots of dimensions „Ls‟ and „ws‟ are cut on one of the radiating edge of SMSA as shown in Fig. 1(a). The slots tune the orthogonal TM02 mode frequency in SMSA with respect TM10 mode as shown in Fig. 1(c), to yield wider BW as shown in Fig. 1(d). For „Ls‟ = 6.0, „ws‟ = 0.4, and „xf‟ = 2.6 cm, simulated and measured BW in E-shape patch are 213 MHz (19.42%) and 205 MHz (19.03%). The E-shape patch exhibits broadside pattern over the BW with peak gain of above 7 dBi.
Amit A. Deshmukh al.Shefali / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, et and Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 1. (a) Top and (b) side views of E-shape MSA backed by pairs of slots cut ground plane; (c) resonance curve plots for varying „Ls‟; and (d) input impedance plots for equivalent E-shape MSA
To increase the BW in E-shape patch, first pair of slots of length and width „L1‟ and „W1‟ are cut on the ground plane which is below the other radiating edge of E-shape patch as shown in Fig. 1(a). To optimize for BW, parametric study for variation in length „L1‟ is carried out and resonance curve plots for the same are shown in Fig. 2(a). The structure of the MSA is similar to parallel plate capacitor where two plates represents the patch and ground plane. Hence any modifications in the ground plane will be linked to that on the patch through the fringing fields that exist between the two plates. Thus, only when the part of slot length „L1‟ lies below the patch, then only it will affect the current distributions on the E-shape patch. Hence in Fig. 2(a), only incremental overlapping slot length that lies below the E-shape patch is considered and thus plots are shown for „L1g‟ = 0, 1, 2 and 3 cm. For „L1g‟ increasing from 0 to 2 cm, not much variation in resonance curve plots is noted. However, for „L1g‟ = 3 cm, additional peak nearer to TM10 mode of the patch is seen. The surface current distributions at observed resonant modes for „L1g‟ = 3 cm is shown in Fig. 3(a – d). At first and third peak, current variations due to TM 10 and TM02
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modes on the patch are noted. At second peak current shows two half wavelength variations on the ground plane. This variation is due to TM02 mode on the square ground plane. To prove that this mode is due to the ground plane, coaxially fed square patch of length 14 cm is simulated for increasing slot length (E-shape patch) and its resonance curve plots are shown in Fig. 2(b, c).
Fig. 2. (a) Resonance curve plots for E-shape MSA backed by pair of slots cut ground plane for increasing „L1g‟; and (b, c) resonance curve plots for increasing slot length for E-shape MSA with patch length „Lg‟ = 14 cm
With increasing slot length, patch‟s TM02 and TM12 mode frequencies reduces. As observed from Fig. 2(c), for slot length of 5 cm (L1g = 3 cm), resonance peak due to modified TM 02 mode is formed nearer to the same frequency position as observed in Fig. 2(a). This modal variation supports that additional mode introduced in E-shape MSA backed by pair of slots ground plane is due to ground plane TM 02 mode. The optimum BW for this configuration is obtained for, „L1g‟ = 2.8, „w1‟ = 0.4, „y1‟ = 3.1 and „xf‟ = 2.6 cm as shown in Fig. 3(e). The simulated and measured BW‟s are, 233 MHz (21.4%) and 239 MHz (22.35%), respectively. As compared with E-shape patch, this DGS antenna yields additional 3% of BW. It shows broadside pattern over the VSWR BW with peak gain above 7 dBi. To further enhance the BW, second pair of slots is embedded on the opposite edge of the ground plane, as shown in Fig. 1(a). The resonance curve plots for increasing slot length „Lp‟ is shown in Fig. 3(f).
Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 3. (a – d) Surface current distributions at observed resonant modes for E-shape MSA backed by pair of slots ground plane for „L1g‟ = 3 cm; (e) input impedance plots for optimum design of E-shape MSA backed by pair of slots ground plane; (f) resonance curve plots for increasing slot length „Lp‟; (g) plots for equivalent SMSA with „Lg‟ = 14 cm with increasing slot lengths; and (h) optimum input impedance plots for wideband E-shape MSA backed by two pairs of slot lengths
With increasing length „Lp‟ additional resonant mode is observed at a frequency which is higher than TM10 mode frequency of the patch. The current distribution at this mode reveals that this is due to modified TM 12 mode on the
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ground plane. To support this, ground plane was separately simulated as a SMSA loaded with two pairs of slots on each of its radiating edge, i.e. „L1‟ and „Lp‟. The resonance curve plots for the same with „L1‟ = 5 cm and increasing „Lp‟ is shown in Fig. 3(g). It is observed that with second pair of slots, modified TM12 mode frequency of the patch reduces and for „Lp‟ = 3 cm, it is formed nearer to the same frequency location at which additional mode is observed for E-shape MSA backed by two pairs of slot cut ground plane. This confirms that additional mode here is the modified TM12, that increases the BW. The optimum response is obtained for „Lp‟ = 3, „wp‟ = 0.4 and „yp‟ = 4.0 cm as shown in Fig. 3(h). The simulated and measured BW‟s are 318 MHz (28.12%) and 322 MHz (28.83%), respectively. Thus as compared to E-shape MSA, two pairs of slot cut design yields 10% increment in the BW. Pattern and gain variation over the BW for this configuration is shown in Figs. 4(a – d) and 5(a), respectively. Across the BW, radiation pattern is broadside with E-plane directed along = 00. The peak broadside co-polar antenna gain is above 7 dBi. The fabricated prototype of the configuration is shown in Fig. 5(b, c).
Fig. 4. (a – d) Radiation pattern at two frequencies over the BW for E-shape MSA backed by two pairs of slots cut ground plane
In the proposed paper, wide band design of E-shape MSA using DGS is proposed which yields 10% additional BW as compared to the E-shape patch. In the reported papers, different configurations for wide band and multi-band response using DGS have been reported. However, in them an explanation about working of antenna in terms of patch resonant modes was not provided. Proposed work provides an original explanation for antenna working in terms of the resonant modes excited in patch and the ground plane. The similar work providing such detailed study is not available in the literature, and that is the novelty here. The proposed design is not targeted at any specific application but it provides systematic explanation for wideband behaviour of MSA backed by DGS structure.
Amit A. Deshmukh et al. / Procedia Computer Science 143 (2018) 101–107 Amit A. Deshmukh, Amita Mhatre, Chinmay Kudoo, and Shefali Pawar / Procedia Computer Science 00 (2018) 000–000
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Fig. 5. (a) Gain variation over BW and (b, c) fabricated prototype of E-shape MSA backed by two pairs of slots cut ground plane
3. Conclusions Wide band designs of E-shape MSA backed by pair of slots cut square ground plane is presented. The first pair of slot tunes TM02 mode frequency on the ground plane to yield more than 230 MHz (>21%) of BW, which is 3% more as compared to the E-shape patch. Addition of second pair of slots on the ground plane tunes next higher order TM12 mode frequency on the ground plane which yields more than 300 MHz (>28%) of BW, that is 10% additional BW against E-shape patch. The present works provides original explanation about working of antenna in terms resonant modes on patch and ground plane, which is not explained in detail in reported work. This is the novelty here. References [1] Wong, K. L. (2002) “Compact and Broadband Microstrip Antennas” John Wiley & sons, Inc., New York, USA. [2] Huynh, T., and Lee, K. F (1995) “Single-Layer Single-Patch Wideband Microstrip Antenna.” Electronics Letters 31 (16): 1310-1312. [3] Lee, K. F., Yang, S. L. S. et al. (2010) “The Versatile U-slot Patch.” IEEE Antennas & Propagation Magazine 52 (1): 71 – 88. [4] Kumar, G., and Ray, K. P. (2003) “Broadband Microstrip Antennas”, Artech House, USA [5] Wong, K. L., and Hsu, W. H. (2001) “A Broadband Rectangular Patch Antenna with a Pair of wide slits.” IEEE Transactions on Antennas & Propagation 49: 1345 – 1347. [6] Guo, Y. X., Luk, K. M. et al. (1999) “U-slot circular patch antennas with L-probe feeding.” Electronics Letters 35 (20): 1694 – 1695. [7] Tong, K. F., Luk, K. M. et al. (2000) “A Broadband U-slot Rectangular Patch Antenna on a Microwave Substrate.” IEEE Transactions on Antennas & Propagation 48 (6): 954 – 960. [8] Guo, Y. X., Luk, K. M. et al. (1998) “Double U-slot rectangular patch antenna.” Electronics Letters 34 (19): 1805 – 1806. [9] Chakraborty, Ujjal, Chowdhury, S. K. et al. (2013) “Frequency tuning and miniaturization of square microstrip antenna embedded with „„t‟‟shaped defected ground structure.” Microwave & Optical Technology Letters 55 (4): 869 – 872. [10] Wang, T., Yin, Y. Z. et al. (2012) “Compact triple-band antenna using de-fected ground structure for wlan/wimax applications.” Progress In Electromagnetics Research Letters 35: 155-164. [11] Deshmukh, Amit A., and Ray, K. P. (2013) “Analysis Of Broadband -shaped Microstrip Antennas. IEEE Antennas and Propagation Magazine 2013; 55 (2): 107– 123. [12] Deshmukh, Amit A., and Ray K. P. et al. (2012) “Analysis of slot cut Broadband and Dual band Rectangular Microstrip Antennas.” IETE Journal of Research; 59 (3): 193 – 200. [13] Deshmukh, Amit A., and Ray, K. P. (2017) “Analysis and Design of Broadband U-slot cut Rectangular Microstrip Antennas.” Sadhana – Academy Proceedings in Engineering Science, Springer Publication; 42 (10): 1671 – 1684,