Ring Shape Microstrip Antenna Backed by Modified Ground Plane for Multiband Response in GSM and Radar Applications

Abstract

Ring shape microstrip antenna designs supported via an altered ground plane profile are proposed for multi-band response with wider bandwidth in each band. The impedance bandwidth of a single ring patch supported via a slot cut ground plane on a substrate having a thickness of ~ 0.1λ_g, is 45.8% and the broadside gain is 5.6 dBi. By employing additional stack patches, dual and triple-band configurations are obtained. In the respective operative frequency bands, maximum 15% of bandwidth is achieved in the suggested antenna, with a maximum broadside gain of more than 5.5 dBi. Through the acquired antenna features, the proposed configuration fulfills the criteria of E-GSM900/Secondary Surveillance Radar/Aeronautical Radio Navigation Applications.

Index Terms
Modified ground plane; Proximity feed; Rectangular slot; Ring shape microstrip antenna

I. INTRODUCTION

In recent decades, technologies based on wireless communication have grown in popularity and demand. Designing a multiband antenna is crucial to satisfy the demands for frequency agility of contemporary wireless technologies. Microstrip antenna (MSA) are notably in demand in the modern communication system despite their low bandwidth (BW) and gain, but owing to their compact profile, lightweight, besides simplicity of system integration [¹] - [⁴]. A number of methods, such as the use of an electrically thicker substrate, parasitic patches, and altered patch geometry in the form of slots or stubs, can be employed to provide a multiband response that offers BW enhancement [¹] - [⁴]. The slot cut approach is employed as it offers compactness [⁵] - [⁶], whereas tuning stubs are favored for frequency tuning [⁷]. The achieved BW is lower in the multiband designs stated in [⁸] - [⁹] despite being built on an electrically thicker substrate. Artificial magnetic conductors or meta-surfaces are employed for gain enhancement in [¹⁰] - [¹²]. The technique reported here increases the configuration's overall cost and the complexity. Owing to the fractal geometry, the complexity of the structure increases for a multi wide band antenna reported in [¹³]. With the inclusion of biasing circuits, reconfigurable designs incorporating active devices make the implementation complex [¹⁴] - [¹⁶]. For the realization of penta-band response, slots, and stubs are used in [¹⁷]. The defected ground plane structure and slots are used to obtain dual-band response in [¹⁸], [²⁴]. The combination of slots, stubs, and shorting posts is used for tuning multiband response in [¹⁹ ] - [²³]. All these reported configurations do not cover in detail how the modifications incorporated in the main patch or the ground plane alter the input impedance and the resonance frequency at patch resonant modes, to yield the multiple frequencies.

Proximity-fed ring shape MSA variations on air-suspended FR4 substrate, covering a frequency range of 1000 MHz, are presented in this paper. Initially, the offset proximity-fed design of a basic circular ring patch is discussed that yields an impedance BW of 128 MHz (10%). Further, a combination of defects on the ground plane in the form of rectangular slots and vertical stub on the patch yields an optimum separation between the degenerated fundamental modes of the ring patch (TM_01d and TM_01v) that gives a wider impedance BW of 534 MHz (45.8%), offering broadside gain of more than 5 dBi. Electromagnetically coupled stacked variations of proximity-fed stub loaded ring shape MSAs with a ring shape MSA or stub loaded ring shape MSA are proposed, which yields dual-band or triple-band response, offering a frequency agility. The optimum dual-band antenna employing a stacked ring patch covers two frequency bands: 970 MHz and 1267 MHz with respective BW of 16.9% and 18.3% and broadside gain of 5.7 and 4.6 dBi, individually. The triple band antenna, employing stub loaded stacked ring MSA, covers frequency bands of 1002 MHz, 1125 MHz, and 1322 MHz with a respective BW of 16.5%, 6.9%, and 7.1% and a broadside gain of 5.4, 4.8, and 3.2 dBi respectively. All configurations exhibit a broadside radiation pattern. Projected multi-band configurations yields a frequency agility fulfilling the criteria for E-GSM900/Secondary surveillance radar/aeronautical radio navigation applications.

The uniqueness of the present investigation is in the detailed explanation of recognition of multi-band response with a wider BW in each band through the analysis of the degenerated resonant mode excitation in proximity-fed ring shape MSA. The proposed design is easier to fabricate and provides a noticeable gain and BW compared to the reported multiband MSAs that have a BW of over 5% in each band. Further closely spaced frequency bands are observed with bearing ratios of 1:1.3 and 1:1.12:1.31, in dual band and triple band configurations. The paper continues with a thorough comparison stressing the innovative aspects of the suggested investigation. Initial IE3D simulations [²⁵] are used to optimize the configurations revealed in this paper, then the measurements are taken. The ring shape MSA is excited using a 50 Ω SMA connector of 0.12 cm inner wire diameter. Within the antenna laboratory, utilizing high-end instruments like ZVH-8, FSC 6, and SMB 100A, the simulation results' experimental validation for input impedance, radiation pattern and gain has been completed. Setting up for more precise measurement, it employs the three-antenna gain approach to evaluate gain in a laboratory. The findings of simulations and measurements show high agreement.

II. STUB LOADED RING SHAPE MSA BACKED BY RECTANGULAR SLOTS CUT GROUND PLANE

A more compact version of circular MSA (CMSA) is the circular ring-shape MSA and it is derived by cutting a circular slot in the patch center [⁴]. A variation of the electromagnetic feeding technique, proximity feeding achieves an improvement in MSA BW on a thicker substrate [³] - [⁴]. Using the same, the design of circular ring MSA supported by rectangular slots cut ground plane is proposed as revealed in Fig. 1(a), Fig. 1 (b). In proximity feeding, fringing fields from the coupling strip are coupled to the radiating patch that excites the resonant mode in the ring shape antenna.

Fig. 1
(a) Top and (b) side views, (c) simulated reflection coefficient (S₁₁) & resonance curve plots, and (d) surface current distributions for the offset proximity fed circular ring MSA

A thicker substrate suspended design is chosen, comprising of two FR4 substrate layers (ɛ_r = 4.3, h = 0.16 cm), separated by a h_a cm air gap. The paper refers to the patch dimensions and frequencies in ‘cm’ and ‘MHz’ respectively. To achieve the fundamental mode frequency of 1000 MHz in ring MSA, for h_a = 2.8 cm, h_s = 2.6 cm, L_s = 1.6 cm and ground plane dimensions as, L_g = W_g =16 cm, the ring patch dimensions are parametrically calculated using IE3D simulations as r₂ = 5 & r₁ = 3.0 cm. At the fundamental resonant mode, MSA shows a broadside radiation pattern. The present study aims at realizing multi-band antenna to offer a broadside pattern in each band. For broadside patterns across each band, variations of fundamental mode are only needed and this is possible by realizing the degeneration of the fundamental mode. Hence initially the ring MSA is fed at an offset feed position, i.e. at x_f, y_f = 2.0, 2.5 cm, as shown in Fig. 1(a). As seen from the provided simulated results in Fig. 1(c), with offset feed position also, a single peak in the resonance curve is noted and MSA shows an impedance BW of 128 MHz (10%). According to the surface current circulation at the corresponding resonant peak in Fig. 1(d), there is a half-wavelength variation around the patch's diameter besides a diagonal variation in 45⁰ directions. Owing to this variation, the resonant mode is stated as TM_01d mode. The ‘d’ refers to the diagonal variation. To further explore the degeneration of the fundamental mode, perturbation in current components at TM_01d mode is needed. For this modification in the ground plane is considered. The current perturbation can be achieved by placing a slit or stub on the patch, but this affects the shape of the geometry. Hence ground plane slot is selected. As depicted in Fig. 1(a), two rectangular slots, each measuring length l_sh and width w₁, are embedded along the ground plane's width. The slot is oriented on the ring patch so that its length is orthogonal to the currents in TM_01d mode. A parametric analysis of the effects of ground plane slots is conducted. Fig. 2(a) displays resonance curve plots for two slot lengths. When the ring patch is covered by the slot length l_sh (l₁ = 2.0 cm), then degeneration of fundamental mode is noted.

Fig. 2
(a) Resonance curve plots for ground plane slot length variation, (b, c) surface current distribution at the two degenerated modes, and (d) S₁₁ BW and gain plots for circular ring MSA backed by slots cut ground plane

Fig. 2(b), Fig. 2(c) displays surface current distributions at degenerated modes. The diagonal axis continues to be the path of surface currents in the first mode. Currents in the second mode vary in the vertical direction. With these current variations, respective modes are mentioned as TM_01d and TM_01v. By optimizing the slot length, optimum spacing between the two modes is obtained. Further, the optimization of the feed location yields maximum BW as depicted in Fig. 2(d). The optimized antenna dimensions are l_sh = 5.0 cm, w₁ = 1.0 cm, h_a = 2.6 cm, h_s = 2.5 cm, L_s = 1.0 cm, x_f = 1.5, and y_f = 2.6 cm. The simulated and measured BW in circular ring MSA backed by slot cut ground plane is 481 MHz (42.17%) and 479 MHz (42.71%), respectively. Over the whole S₁₁< -10 dB BW, antenna broadside gain is greater than 5 dBi. Broadside radiation pattern is appearing across the BW with a cross polar level of less than -14 dB as opposed to a co-polar level. The E-plane is aligned along Φ = 90⁰ over the BW. An increment in the ground plane slot length beyond 5 cm is not considered as it creates a complete slot below the ring patch. The TM_01d and TM_01v resonant modes are not orthogonal and hence circular ring MSA with slot cut ground yields linear polarized wideband response.

For further increase in BW, tuning of the two modes is needed. In the middle of the ring patch, a stub of length w₂ and width l_sv is positioned to accomplish this, as shown in Fig. 1(a). This stub position creates a shorter path length for currents at TM_01v mode, which increases its frequency and thus increases the BW as depicted in Fig. 3(a). For w₂ = 1.5 cm, x_f = 1.7, and y_f = 2.8 cm, the construction of a loop inside the VSWR = 2 circle produces the finest results. As depicted in Fig. 3(b), the simulated BW is 534 MHz (45.8%) whereas the measured BW is 524 MHz (45.9%). Antenna broadside gain is more than 5 dBi across S₁₁ BW. Polar plots in Fig. 3(c)- Fig. 3(f) displays radiation pattern that are closer to the BW's band start and stop frequencies. At frequencies publicized and over the complete BW, the pattern remains in the broadside direction with the E-plane aligned along Φ = 90⁰. The cross polar radiation is below 8 - 10 dB with respect to co-polar levels. A higher contribution of the cross-polarization level is attributed to the small contribution of horizontal currents due to the diagonal variation of resonant mode currents. The fabricated prototype for the stub loaded circular ring MSA is depicted in Fig 4.

III. ELECTROMAGNETICALLY COUPLED MULTIBAND VARIATIONS OF RING SHAPE MSAS

Multi-band response offering wider BW in each band is obtained when a greater number of resonant modes are present in the configuration. To explore the same, electromagnetically coupled stacked configuration of ring MSAs is considered as shown in Fig. 5(a). With a circular ring geometry, a planar gap-coupled design will not produce the best coupling within fed and parasitic patches owing to the smaller coupling area through a single tangential point which leads to inadequate BW improvement. and hence the stacked design is considered. Two variations of stacked configurations; the first one with ring shape MSA and the second with stub loaded ring shape MSA is explored. Dimensions among a stub with a width of w₂ = 1.5 cm on the stacked patch, as illustrated in Fig. 1(a), the stacked ring MSAs variations are kept the same as that of fed ring MSA, but an air gap among the two patches is altered to tune the respective modal frequencies.

Fig. 3
(a) Resonance curve for circular ring shape MSA with and without stub, (b) S₁₁ BW and gain plots, radiation pattern nearer to band (c, d) start and (e, f) stop frequencies of BW for stub loaded circular ring MSA backed by rectangular slots cut ground plane.

Fig. 4
Fabricated prototype of stub-loaded ring shape MSA backed by slot cut ground plane.

In the two stacked variations, resonance curve plot in Fig. 5(b) displays four peaks. A dual wideband response is observed in the combination of fed stub loaded ring MSA stacked with a ring MSA. As the inter-spacing between the modal frequencies on the ring patches changes with the placement of the stub on the stacked ring MSA, dual band response changes to the triple frequency response with BW greater than 5% in each band, for stub loaded ring patch stacked on the fed stub loaded ring patch. The dimensions of the fed and stacked patches and the air gap between them are parametrically optimized using IE3D simulations for the respective responses. In the dual wideband response, fed patch antenna parameters are, r₁ = 3, r₂ = 5, w₂ = 1.5, h_a = 2.6, h_s = 2.5, L_s = 1.0, x_f = 1.7, y_f = 2.8 cm. The dimensions of the stacked patch are the same as that of the fed ring MSA, but it is placed at h₁ = 0.7 cm above the fed ring MSA. Fig. 6(a) displays the S₁₁ BW and gain plots for optimized dual band configuration.

Fig. 5
(a) Side view for multi-layer stacked configuration, (b) overlapped resonance plots for all the variations of the proposed ring shape MSA.

Fig. 6
(a) S₁₁ BW and gain plots and radiation patterns at the center frequency of (b, c) first and (d, e) second band for the dual-band stacked ring shape MSAs

Respective simulated impedance BW across the two bands are 178 MHz (16.5%) and 215 MHz (18.2%). While the equivalent measured values are 180 MHz (16.9%) and 213 MHz (18.3%), respectively. Simulated and measured gain across the first band is more than 5 dBi while in the second band, it is above 4 dBi. Fig. 6(b) - Fig. 6(e) displays the radiation patterns at the center frequency of each band. The pattern is broadside-directed and the cross-polar level against the co-polar component of radiation is less than 8 dB. The E-plane of radiation is aligned along Φ = 90⁰. With the above antenna characteristics, the proposed antenna fulfills the necessities of E-GSM900 (880 - 960 MHz), aeronautical radio service navigation (1164 to 1215 MHz, 1215 -1240 MHz, 1240-1300 MHz, 1300 - 1350 MHz). The fabricated antenna is shown in Fig. 7.

Fig. 7
Fabricated prototype of stacked ring shape MSAs for dual wideband response

A triple frequency response is achieved using the same antenna dimensions as those used in the dual band design and with the positioning of a stub with a width of w₂ = 1.5 cm on the stacked patch. Thus, configuration consist of fed stub loaded ring MSA stacked with a stub loaded ring MSA. As shown in Fig. 8(a) the simulated impedance BW across the respective bands are 179 MHz (16.7%), 79 MHz (6.7%), and 97 MHz (6.9%), while the respective measured values are 176 MHz (16.5%), 81 MHz (6.9%), and 99 MHz (7.1%). The simulated and measured gain across the first band is more than 5 dBi while for the second band, it is more than 4 dBi. In the third band gain is more than 3.0 dBi. The three consecutive band center frequencies have a frequency ratio of 1:1.12:1.31. This ratio shows strong frequency agility amongst subsequent bands, which helps prevent channel interference. The simulated and measured radiation patterns observed at the center frequencies of the three bands are shown in Fig. 8(b) - Fig. 8(e) and Fig. 9(a), Fig. 9(b). The pattern in three bands shows maximum in the bore-sight direction with cross polarization level of less than 8 dB against the co-polar level. With this achieved BW, pattern and gain characteristics, the proposed antenna fulfills the necessities of E-GSM900 (880 - 960 MHz) and Secondary surveillance radar (SSR) uplink (1030 MHz) as well as downlink (1090 MHz) frequencies, and service aeronautical radio navigation (1300 - 1350 MHz).

Fig. 8
(a) S₁₁ BW and gain plots and (b - e) polar radiation patterns at the center frequency in the first & second bands for triple-band ring shape MSA

Fig. 9
(a, b) Radiation pattern at the center frequency of the third band and (c) fabricated prototype of ring shape MSA for the triple-band response.

The Fig. 9(c) displays the fabricated prototype for the triple frequency design. In the antenna lab, measurements of the suggested design's input impedance, pattern, and gain are made by means of instruments, ZVH - 8, FSC 6, and SMB 100A. The distinctions in substrate characteristics, air gap, feed point location, and antenna size are what cause the observable differences between the measured and the simulation results.

IV. RESULTS DISCUSSION AND COMPARATIVE ANALYSIS

The paper presents designs of ring shape MSAs for dual and triple frequency response. A comparison of the technical innovation in the proposed study and the findings achieved in stated multi-band MSAs appears in Table I. The comparison is presented based on a number of frequency bands and respective BW, techniques to achieve the said response, peak gain in the respective bands, and the antenna volume, i.e patch area (A_p) and total substrate thickness (h_t).

TABLE I
COMPARISON OF THE PROPOSED MULTIBAND RING SHAPE MSA AGAINST REPORTED PAPER

MSA shown in	fc, BW MHz (%)	Frequency ratio f2/f1, f3/f1 f3/f2	Tuning element	Peak Gain (dBi)	Ap/ λc , ht/ λc)
Fig. 7	970 (16.9), 1267 (18.3),	1.30	slot, stub	5.7, 4.6	2.6λc, 0.1λc
Fig. 9(c)	1002 (16.5), 1125 (6.9), 1322 (7.1)	1.12,1.31,1.17	slot, stub	5.4, 4.8, 3.2	2.6λc, 0.1λc
[8]	1300 (3), 1800 (4.3), 2330 (3.5)	1.38, 1.79, 1.29	slot	__	1.17λc, 0.06λc
[9]	2440 (6.6), 5730 (4.8)	2.36	slot	6.8, 2.1	1.6λc, 0.06λc
[10]	3360 (-), 5670 (-), 9100 (-)	1.68, 2.70, 1.60	__	3.3, 6.3, 11.7	6.5λc, 0.08λc
[11]	2400 (1.3), 4200 (42), 5800 (15)	1.75, 2.41, 1.38	__	4.2, 1.9, 3.46	2.0λc, 0.25λc
[12]	2360 (24), 8450 (10.36)	1.43, 2.14, 1.49	__	2, 4.5	0.53λc, 0.015λc
[13] Antenna-II	3400 (-), 4600 (-), 6000 (-), 8000 (-), 10400 (-), 12400 (-), 13700 (-)	1.35, 1.76, 1.30	_	5.32, 1.84, 0.82, 3.2, 3.4, 5.4, 20.4	1.02λc, 0.014λc
[14] At port 1 diode on	3600 (1.05), 6780 (7.3), 9080 (0.69), 13150 (0.52), 15330 (13.8), 17550 (22)	1.05, 2.52, 2.40	Slot, PIN diode	8	4.4λc, 0.02λc
[15] Triple band	859 (15), 1592 (6.83), 2450 (4.9)	1.85, 2.85, 1.53	PIN diode	__	1.63λc, 0.65λc
[16]	5210 (2.6), 9410 (9.6) 10460 (3.9), 12690 (6.4), 14390 (3.0), 17090 (17)	1.80, 2.0, 1.1	PIN diode	3.96	1.57λc, 0.02λc
[18]	2460 (38), 5100 (13)	2.36	slots	2.5, 4.2	0.2λc, 0.012 λc
[21]	2400 (38), 3700 (13)	1.54	__	4.3	0.5λc, 0.012λc
[22]	1900 (4), 3500 (2.2)	1.84	Shorting pins	1, 2.4	0.2λc, 0.013λc
[23]	2400 (10), 5500 (6)	2.29	slots	1, 0.26	0.65λc, 0.012λc
[24]	3530 (12.5), 6830(4.5)	1.93	slots	4, 3.38	1.32λc, 0.019λc
[26]	1176 (2.5), 1227 (2.2), 1575 (1.1), 2300(2.7)	1.04, 1.34, 1.283	slots	3.4, 2.91, 2.23, 2.7	2.6λc, 0.02λc
[27]	2423 (5), 3381 (2), 4233 (9.5)	1.39, 1.75, 1.25	stubs, slots	7.5, 8.7, 8.7	> 5λc, 0.06λc
[28]	708 (3), 1053 (17), 1975 (4.7)	1.48, 2.78, 1.87	Parasitic patch	7.6, 7.2, 7.3	5.3λc, 0.03λc
[29]	3683 (1.57), 5910 (2.23)	1.6	slot, shorting post	10.2, 10	3.02λc, 0.036λc
[30]	2050 (0.5), 2750 (4), 3800 (5.5), 6500 (19.5)	1.34, 1.854, 1.382	Parasitic patch	2, 1.3, 3.1, 3.3	2λc, 0.065λc
[31]	1184 (2.7), 1580 (2.5)	1.334	slots	3.68, 3,31	1.92λc, 0.02λc

Multiband configurations reported in [⁸] - [⁹] yield lesser BW in the respective bands, although fabricated on a thicker substrate. Against this the proposed multiband configuration yields wider BW in each band. Owing to the use of metamaterial and artificial magnetic conductor (AMC) for to obtain the gain and BW enhancement, the overall complexity, cost, and volume of the configuration increases for the triple and dual-band designs reported in [¹⁰] - [¹²]. Inspite of the AMC strcuture, gain offered by the antenna discussed in [¹⁰] is lower or comparable against the proposed design. In opposition to these, proposed configurations are made using a low cost FR4 substrate that is suspended in the air. The complexity of the structure for a multiband antenna mentioned in [¹³] to obtain a wideband response grows due to the nested integrated fractal geometry. Reconfigurable designs with active devices as discussed in [¹⁴] - [¹⁶], make the implementation challenging because of the biasing circuits. The configurations described in [¹⁸], [²⁴] exploit a modified ground plane structure to realize a multi-band response. But the study presented in the same does not explain how a changed ground plane produces the results that are shown, while explaining effects on the resonant modes of the patch geometry. In order to achieve dual band response, two square rings with quadrilateral feed patches are used in [²¹], shorting pins are used for tuning of dual band response in [²²], while multiple slots are intended for the recognition of dual band response in [²³]. Against these configurations, the proposed design employs a pair of rectangular slots on the ground plane and offers larger BW in each band with a higher gain. The multi-band antenna reported in [²⁶] employs multiple stack patches with equivalent patch area. But it has lower BW and gain in respective operating bands. The triple frequency design discussed in [²⁷] has larger patch area as it employs microstrip line fed aperture coupling technique to excite the multiple resonant modes. Further it offers lower impedance BW in respective bands against the proposed triple frequency antenna. With the overlap patches employed in the multi-band design discussed in [²⁸], patch size is larger. The slot cut and shorting posts loaded differential fed design employing circular patch is reported for dual band response in [²⁹]. Although it offers higher gain in the two bands, but the BW in dual bands is smaller with a higher antennas size. Further, the details about resonant modes present in the multiple shorting posts loaded circular patch that achieves dual band higher gain response are not explained. For a comparable patch area, multi-band designs discussed in [³⁰] - [³¹] offers lower BW and gain in first three operational frequency bands against the proposed antenna.

In some of the reported configurations considered in the comparative analysis in Table I, designs are optimized on thinner efficient microwave substrates or presented in the higher frequency range. Because of this, they have smaller area against the proposed stacked patch designs. The selection of efficient substrates increases the cost. Against this, proposed work employs a low-cost lossy substrate in air suspended configuration thus providing a cost-effective solution. In suspended substrate designs, an effective dielectric constant approach to that of the air that leads to the patch size increment in the proposed antennas. However, in Table I comparison is also presented for reported antennas having thicker substrates. In comparison against them, antenna size in proposed antennas is smaller.

Thus, in comparison to the published work, the present study proposes a simple proximity-fed multiband stacked ring shape MSAs having a total patch area of 2.6λ_c, on a substrate thickness of 0.1 λ_c by using rectangular slots cut ground plane. The design offers smaller frequency ratio (< 1.3) between the multiple frequencies. Although the area of the proposed configurations is more than a few of the reported literature configurations, the design yields BW of 16.9 % and 18.3% in the dual-band configuration, while a BW of 16.5%, 6.9%, and 7.1% in the triple band configuration. Across the respective bands, multi-band antennas show co-polar gain in the range of 3.2 dBi to 5.7 dBi, using a low cost lossy FR4 substrate in the air-suspended configuration. The proposed antenna meets the criteria for frequency agility owing to its simple construction, improved impedance BW, gain, and frequency ratio, and covering wireless applications like E-GSM900 /Secondary surveillance radar/aeronautical radio navigation.

V. CONCLUSIONS

The proximity-fed wideband design of stub loaded circular ring shape MSA supported via ground plane embedded with rectangular slots is proposed. The ground plane's slots and stub positions on the patch aid in optimizing the separation between the patch’s degenerated TM_01d and TM_01v resonant modes to achieve the impedance BW of greater than 45%. To cater to the frequency agility applications, multi-band designs using stacked variations of circular ring shape MSAs are proposed. The dual band variation offers BW of 16.9 % and 18.3% in each band with a frequency ratio of 1:1.3. The triple band design offers 16.5%. 6.9% and 7.1% of BW in three bands with frequency ratios of 1:1.12, 1:1.13, and 1:1.17 with reference to the first band frequency. For the total patch area of 2.6λ_c, and substrate thickness of 0.1 λ_c, both the designs offer broadside linear polarized radiation patterns through a gain of above 3 to 5 dBi, across all the bands. The proposed multi-wideband configurations are useful in frequency agile applications and are useful to cover wireless applications like E-GSM900 /Secondary surveillance radar/aeronautical radio navigation.

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Publication Dates

• Publication in this collection
  10 June 2024
• Date of issue
  May 2024

History

• Received
  10 Dec 2023
• Reviewed
  15 Jan 2024
• Accepted
  19 Apr 2024