Search

This letter presents a methodology for the design of high-performance miniaturized Circular Power Dividers (CPDs) for wideband applications. To accomplish this objective, annular slots are strategically incorporated into patch and the ground plane of CPDs. This, in turn, increases the effective path length of the surface current flowing across the patch. This yields miniaturization, improved impedance matching, reduced insertion loss and increased isolation over a larger bandwidth. A mathematical model is developed for the design of the proposed configuration called Circular power dividers with Defected Ground Plane(CDGP). The presented model has been verified through various simulations and practical measurements. By implementing this approach, a substantial miniaturization of approximately 83% and more than threefold increase in bandwidth has been achieved when compared with non-slotted CPDs. Moreover, there is improvement in insertion loss, isolation, and return loss as well. There is good agreement between the mathematical model, simulation results and measured parameters. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive overview of Gallium nitride (GaN)-based power amplifier (PA) design for various frequency bands. GaN-based technology has emerged as a promising alternative to traditional silicon-based amplifiers due to its superior performance characteristics, which are discussed in this paper. This paper also discusses the key design parameters and challenges associated with PA design. Various design techniques and topologies for GaN power amplifiers are explored besides addressing theoretical considerations of PA design along with a complete systematic design procedure for L-Band amplifier using the wolfspeed large signal GaN HEMT model. To further demonstrate the useful methodology, the designs of S-band and C-band PAs are also presented. GaN-based devices are very promising candidates for high-power applications. It is widely used in various high-power applications including communication and radar. [ABSTRACT FROM AUTHOR]

This paper analyses the effect of introducing multi-cavity-backing up to four cavities on a two-layered suspended stacked one bottom four top rectangular microstrip antenna. The analysis brings out the concurrent enhancement of bandwidth, gain and isolation between two antennas with progressive cavity-backing up to three cavities. Compared to stacked rectangular microstrip antennas without cavity, the single and triple cavity-backed configurations yielded a 40% and 83% enhancement in bandwidth and 0.80 and 2.20 dB enhancement in gain, respectively. The proposed novel triple cavity-backed one bottom four top rectangular microstrip antenna yields a bandwidth of 65.2% and an average gain of 12.85 dBi with an efficiency of 89%. The triple cavity-backed configuration yielded cross-polarization of less than −50 dB in both E and H planes and two such proposed antennas with rim-to-rim separation of 0.35 λ0 give uniform isolation better than 40 dB covering the entire bandwidth. Measured results are in close agreement with the simulated one, which validates the performance of the antenna. The proposed antenna is deemed suitable for Through the Wall and Ground Penetrating Radar applications because of the improved characteristics offered by the proposed antenna in the S-band. [ABSTRACT FROM AUTHOR]

In this paper, a new planar printed quasi-Yagi antenna with compact size and wide bandwidth is presented for a multiple-input-multiple-output (MIMO) antenna system. Antenna element consists of a rectangular driven monopole, a strip director, and a coplanar ground shorted reflector. A planar rectangular monopole is used for the first time as a driven element instead of a dipole to avoid the implementation complexity of BALUN as it can be fed directly by an unbalanced coaxial feed. It has been shown that the antenna element has an impedance bandwidth (|S11| < −10 dB) of 60.5% ranging from 1.59 to 2.97 GHz. Based on this element, a four-element pattern diversity MIMO antenna is proposed. By utilizing the ground of one element as a reflector for the successive element, a compact size of 109 mm × 109 mm (0.54λ0 × 0.54λ0 at 1.5 GHz) has been obtained. Measured bandwidth of 65.9% (1.5–2.97 GHz) with minimum isolation of 13 dB has been achieved. The measured directional patterns and an average gain of 4 dBi, remain stable in the operating band with cross-polarization levels less than −25 dB. The envelope correlation coefficient and channel capacity loss show good diversity performance. [ABSTRACT FROM AUTHOR]

The harmonic response of a tuned wire/cylindrical monopole antenna has been determined in terms of its input impedance, VSWR, gain, and radiation patterns. The analysis on monopole antenna has been performed using two simulation tools; Numerical Electromagnetic Code (NEC) and CST microwave studios. The designed monopole antenna is mounted on an infinite ground plane using NEC creating an ideal scenario for simulation, whereas, more realistically, the monopole antenna is mounted on a finite ground plane using CST considering the practical requirements. A perfect conductor is used to design the monopole antenna as well as the ground plane. Simulated results using both the software are validated experimentally. The analysis establishes that the Electromagnetic Interference is efficiently radiated by monopole antenna at odd harmonics as the input impedance matching is good at these frequencies and also the gain is high. A mitigation technique without any additional circuitry has been proposed to suppress radiated off-band harmonics. The central idea behind the proposed mitigation technique is to create an input impedance mismatch at the interfering harmonic frequencies, which is achieved by increasing the diameter of the designed monopole antenna causing reduction in input impedance at higher harmonics. The increased diameter in terms of wavelength is still small at fundamental mode. Thus, the performance of the antenna at fundamental frequency remains largely unaffected, whereas, reflection co-efficient becomes very high at harmonics. [ABSTRACT FROM AUTHOR]

A five-element pattern and polarization (linear/circular) diversity multiple-input-multiple-output (MIMO) antenna system has been presented in this article for application in 2.45 GHz WLAN. The proposed configuration consists of a circularly polarized (CP) patch antenna element and four monopole antenna elements placed orthogonal to each other. Broadside CP characteristics are achieved by using a square patch antenna with circular chamfered corners and central axis feed. Simple rectangular monopole antenna elements with microstrip line feed produce four linearly polarized (LP) end-fire directive radiation patterns. It achieves a bandwidth (BW) of 24.1% and 5.1% for the end-fire LP antenna element and broadside CP antenna element (corresponding axial ratio BW is 1.64%), respectively, with minimum port isolation of 15 dB. The ECC and CLL are below 0.03 and 0.5 bits/s/Hz, respectively, showing good MIMO performance. Due to its simple design, compact footprint (93 × 93 mm2), planar structure, and competitive features, the proposed antenna is suited for practical WLAN applications. [ABSTRACT FROM AUTHOR]

This communication presents a novel stacked multi-resonator two-layered suspended rectangular microstrip antenna (MSA) backed by double-cavity, which yields a wide bandwidth (BW) of 64% at the center frequency of 2.6 GHz, due to additional resonances introduced by the cavity. The proposed antenna has high radiation efficiency above 89.5% throughout the band yielding a maximum gain of 14.7 dBi and an average gain of 12.5 dBi. It has a stable radiation pattern and low cross-polarization better than −45 dB and yields uniform isolation better than 40 dB between two such antennas. Compared to without cavity-backed configuration, the proposed double cavity-backed configuration yields 82% more BW, 1.8 dB more gain, and 10 dB more isolation between the antennas. Simulated results are validated by measurements with a close agreement. Improved characteristics of the proposed antenna make it suitable for several applications including through the wall and ground penetrating radars (GPR). [ABSTRACT FROM AUTHOR]

This paper presents the novel design and analysis of a 25 W broadband Class-AB GaN HEMT-based power amplifier working over 0.9–1.7 GHz. A large signal model of the Wolfspeed-make GaN HEMT CG2H40025 has been used in this design. The comprehensive design process has been carried out with the help of the Advanced Design System software by Keysight. Instead of conjugately matching the load and source impedance obtained from load-pull analysis of a nonlinear model of CG2H40025, the value of load and source impedance has been tuned with the help of a novel design approach of an ideal matching design approach. Thus, to achieve an output power of more than 25 W and a flat large signal gain of 15.425 ± 0.375 dB, a novel design approach has been employed to create input and output matching networks, maintaining a lower Q value results in broad bandwidth and for determining the load and source impedances. The circuit has been fabricated on Roger's substrate RO4350B having a dielectric constant of 3.66 and a loss tangent of 0.0031. The unique design approach based on electromagnetic simulation of the circuit at each design step yielded experimental results that agreed very well with the simulated results. The fabricated power amplifier achieves a power-added efficiency of over 54.78% and a drain efficiency of over 55.45% throughout the entire frequency range. It also delivers a maximum output power of 32.18 W at 1.3 GHz. This power amplifier is developed for L-band Foliage Penetrating Radar. [ABSTRACT FROM AUTHOR]

A generalized expression has been derived for resonance frequency of polygonal microstrip antennas with even number of edges using modified magnetic wall method. Nature of polygonal resonators is analyzed with their equivalence to corresponding circumcircle resonators. Magnetic wall has been transformed into a dynamic function of vertex angle of polygons. The transformed magnetic wall includes the effect of non-uniform fringing around vertices and edges. A scheme to achieve the complete response of circular antennas from square and other polygonal antennas has also been presented. The proposed general expression accurately gives resonance frequency of even polygonal antennas at the fundamental frequency as well as higher harmonics. The proposed expression and theory agree with simulation and measured results of different polygonal antennas. [ABSTRACT FROM AUTHOR]

In this article, a new configuration of a compact planar three‐element multiple‐input‐multiple‐output (MIMO) antenna system is proposed based on quasi‐Yagi elements. A simple yet novel monopole driven three elements quasi‐Yagi antenna (QYA) is designed to obtain a directional pattern over an ultra‐wide bandwidth with a simple and compact configuration. The proposed single QYA contains the semi‐elliptical driven monopole, the flared truncated ground plane reflector, a single elongated elliptical director and a simple microstrip feedline. The simulated and measured results showed that the proposed MIMO antenna system operates in an ultra‐wide frequency range, starting from 1.53 to 6 GHz (118.7%, for |S11| < −10 dB), which covers several wireless communication bands. It has a compact total electrical area of 0.21λ02 (λ0 is the highest operating wavelength) and a minimum isolation of 17 dB between its ports with a common ground plane without any complex decoupling structure. For each element, the measured peak gain and simulated total efficiency variations are between 3.3‐5.6 dBi and 77.6%–89%, respectively. There is good agreement between simulated and measured results. Furthermore, the calculated envelope correlation coefficient of < 0.006, channel capacity loss of < 0.2 bit/s/Hz, and stable total active reflection coefficient resonance are obtained over entire operating bandwidth, which conforms satisfactory MIMO/pattern diversity performance for wireless access‐point applications. [ABSTRACT FROM AUTHOR]

In this study, a new configuration of a low profile, broadband printed quasi‐Yagi antenna with two directly fed monopoles has been proposed. The property of a printed monopole antenna with a simple microstrip feed‐line has been used to simplify feeding structure of the printed quasi‐Yagi antenna. A broad bandwidth is achieved by cascading another monopole element of different lengths in a series to obtain two nearby resonances. The proposed antenna consists of two driven monopoles on one side of the dielectric substrate, whereas, on the other side, a reflector and a director are realized as parasitic monopole elements, directly on the ground plane. The measured impedance bandwidth of 70.2% (1.46‐3.05 GHz) with stable gain ranging from 4.7 to 5.3 dBi in the entire bandwidth has been achieved. The antenna has the front‐to‐back ratio better than 10 dB and cross‐polarization level below −20 dB in the direction of maximum radiation over the entire bandwidth. The simulated performance of the antenna has been experimentally verified with good agreement. [ABSTRACT FROM AUTHOR]

A comprehensive analysis on performance of Dolph-Tschebyscheff distribution for different array length and side lobe levels has been presented in this paper. Dolph-Tschebyscheff array, which is a compromise between binomial and uniform array, produces optimum side lobe level, efficiency, and half power beamwidth, hence, it is referred to as optimum distribution. For a larger number of elements, the Tschebyscheff array demands higher side lobe suppression in order to avoid the abrupt amplitude distribution at the edges that results from more elements and lower side lobe suppression, at the same time, higher side lobe suppression decreases aperture efficiency and gain. These novel analyses have been carried out by computing parameters such as power pattern, first side lobe level, directivity and half power beamwidth. Plots for optimum SLL and critical SLL are derived for a range of array elements, which defines three regions assisting in selection of appropriate number of elements and desired major-to-minor lobe levels for linear/planar array antenna designs. Practical array analysis is proposed by approximating the amplitude of arrays' end elements, whenever it becomes higher than their adjacent elements. [ABSTRACT FROM AUTHOR]

Printed rectangular monopole antennas (PRMAs) have been investigated for increasing bandwidth. PRMAs with single, dual and triple microstrip line feed have been studied to show the effect of feed network to enhance the impedance bandwidth. Systematic study has been carried out to show the effects of patch width variation along with its offset feed, which leads to wideband antenna characteristics. The increase in bandwidth in the case of off-centred feed PRMAs is from 1.7 GHz (1.4–3.1GHz) to 3.9 GHz (1.3–5.2 GHz); this is more than 2.2 times as compared to single-centre-feed PRMA. Experiments have been carried out to verify the simulation results, which are in good agreement. [ABSTRACT FROM PUBLISHER]

ABSTRACT A novel compact ultra-wideband slot cut elliptical printed monopole antenna is proposed. The measured bandwidth (BW) from 1.6 GHz to more than 22 GHz (>170%) has been obtained. The gain, radiation efficiency and radiation patterns, over the entire BW, remain similar to that of a printed elliptical monopole antenna with reasonable agreement between simulated and measured results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:631-635, 2014 [ABSTRACT FROM AUTHOR]

Modified design of triangular-shaped microstrip antenna is proposed for circular polarized response which yields an axial ratio bandwidth of 68 MHz (∼5%) in the L-band. Furthermore, its electromagnetically coupled stacked design is presented, which yields enhanced impedance and axial ratio bandwidth of more than 1100 (∼70%) and 90 MHz (>7%), respectively. A single and stacked antenna offers a broadside pattern with a peak gain of 9 dBi. As a part of the design procedure, resonant length formulation at patch modes is presented. This serves as a guideline in the re-designing of similar antenna in a given frequency spectrum. Theoretical results have been verified experimentally with a good agreement. [ABSTRACT FROM AUTHOR]

Microstrip Reflectarrays (MRAs) are typically excited using the horn antenna. In this paper, a different microstrip antenna feed to excite MRA, which is having patches of variable size, is proposed. Three different configurations namely, 2 × 2, five elements arranged in two orthogonal axes, and 3 × 3 element MRAs have been investigated to prove the concept. These configurations were first simulated using IE3D software, followed by their experimental verifications. [ABSTRACT FROM AUTHOR]

This article proposes compact configurations of hexagonal microstrip antennas (HMSA). The hexagonal microstrip antenna is modified by shorting along the zero potential line, perpendicular to the feed axis resulting in shorted half-hexagonal and quarter-HMSA for the two feed configurations along X and Y axes. The fundamental principle is to keep the field distribution same so that the resonance frequency remains unaltered while achieving a compact footprint. The area reduces by a factor of four, for the quarter patch, while maintaining approximately the same resonance frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:604-608, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27396 [ABSTRACT FROM AUTHOR]

A printed sectoral monopole antenna with ultra wide bandwidth has been proposed. This configuration is formed by chopping off a quarter part of a circular printed disc. The ultra wide bandwidth has been obtained in the frequency range from 1.84 to 11.82 GHz with dual polarization radiation patterns. The experimental and simulated results for this proposed antenna are presented, which are in agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2066-2070, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27039 [ABSTRACT FROM AUTHOR]

The dual-band microstrip antennas (MSAs) are realized by placing the stub on the edges of the patch or by cutting a slot at an appropriate position inside the patch. The multiband MSAs are realized by using the combination of the slot and stub. In this paper, by cutting a rectangular slot on the radiating edge and half U-slot on the nonradiating edge of a rectangular MSA, a dual- and triple-band rectangular MSA are proposed. These slots are of nearly quarter wave in length and by changing their lengths, tuning of the frequencies is realized. Also, the multiport network models for these multiband MSAs are proposed, which helps in understanding the mode distributions at slot and patch frequencies. To realize the higher gain, the suspended configurations of these multiband antennas are also proposed. A good agreement is obtained between the simulated, multiport network model, and measured results. [ABSTRACT FROM AUTHOR]

The multi-band rectangular microstrip antennas (MSAs) realised by placing an open-circuit stub on the edges of the patch and by cutting resonant slots inside the patch are proposed. The multi-port network models for these multi-band rectangular MSAs are also proposed which helps in analysing the voltage distributions at various frequencies. Also the multi-band frequency response of these configurations is experimentally verified. [ABSTRACT FROM AUTHOR]

Closed form expressions for the accurate calculation of the resonance frequency of a hexagonal and half hexagonal microstrip antennas, based on their equivalence with rectangular microstrip antenna, have been presented. These proposed empirical formulae have been validated using simulations and experiments. Design curves, for the input impedance variation along the feed axis, have been presented for hexagonal and half hexagonal patches for two feed positions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 448–452, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24087 [ABSTRACT FROM AUTHOR]

Three configurations of compact gap-coupled half hexagonal microstrip antennas have been presented for broad bandwidth. Parametric studies for the effect of coupling gap and feed point location on the performance of these antennas have been investigated and the results have been validated experimentally. Increase in bandwidth is more than twice for the two configurations and about four times for the third case when compared with that of the corresponding hexagonal microstrip antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 271–275, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23069 [ABSTRACT FROM AUTHOR]

Formulations to determine the resonance frequencies of hexagonal and half hexagonal microstrip antennas have been proposed based on their equivalence with circular and semicircular microstrip antennas, respectively. The new configuration of half hexagonal patch formed by bisecting the full hexagon along its resonant length, has the same resonance frequency as that of the full hexagonal patch, with half the size. Simulations and experiments have been performed to validate the proposed method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2876–2879, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22843 [ABSTRACT FROM AUTHOR]

Configurations with slotted rectangular microstrip antennas using rectangular slot and half U-slot cut inside the patch for multi-band operation are proposed. Also, the multi-port network models for these multi-band rectangular microstrip antennas are proposed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2757–2761, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22880 [ABSTRACT FROM AUTHOR]

A rectangular microstrip antenna is gradually divided into equal smaller elements along the width, and lengths of these smaller strips are varied to increase the separation between the resonances to obtain dual and triple frequency operation. Likewise, configurations consisting a maximum of five strips have been investigated. For configurations with two strips only dual frequency operation has been obtained, whereas for configurations with more than two strips both dual and triple frequency operation has been obtained. With increase in number of elements, the separation between different resonances is more and the radiation pattern is also similar in two frequency bands. Experiments have been performed and the results are in agreement with the simulations. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1480–1486, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22452 [ABSTRACT FROM AUTHOR]

Parametric study of ultrawideband printed elliptical monopole antennas have been presented. Design curve for the length of the feed transmission line for various lower band edge frequencies has been generated. Variation of bandwidth with ellipticity ratio of these configurations has also been studied. Experiments have been performed to measure bandwidth and radiation patterns of these configurations, which tally well with simulated results. The elliptical configuration with ellipticity ratio of 1.1 gives ultrawide impedance bandwidth ratio of 12.4:1 as compared to 10.2:1 of the circular monopole antenna. This antenna introduces minimum ringing and distortion/dispersion of the pulse in time domain. [ABSTRACT FROM AUTHOR]

Various new configurations of planar triangular monopole antennas have been investigated. Effect of flaring angle of planar triangular monopole antennas on the bandwidth has been studied. A compact configuration of vertex chopped equilateral triangular monopole antenna has been proposed for ultra wide bandwidth ratio of 9.2:1. Orthogonal vertex chopped equilateral triangular monopole antenna is proposed for obtaining the improved azimuthal omnidirectional radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 628–632, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22214 [ABSTRACT FROM AUTHOR]

Systematic investigations have been presented by splitting a single rectangular microstrip patch into equal, smaller elements along the width, keeping the length same. Of these, one of the elements is fed while others are gap coupled to its nonradiating edges. The rectangular patch is gradually splitted into 2–14 equal, smaller elements and in between coupling gaps are optimized for maximum bandwidth. Parametric study for the effect of gap and feed point location, along with radiation pattern, has also been carried out. A maximum bandwidth increment of over 10 times, compared with that of the original single rectangular patch is obtained for 14 numbers of equal strips. As the additional resonators (at same resonance frequency) are obtained from the original patch itself, the overall configuration remains compact. Experiments have been carried out, which are in good agreement with simulated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2382–2384, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21976 [ABSTRACT FROM AUTHOR]

A novel, compact suspended semicircular patch with a half U-slot antenna is proposed for dual frequency operation. Parametric study of this new configuration is carried out by varying length and width of the slot and the coaxial feed probe radius and its position. The dual frequency ratio from about 1.18 to 1.66 has been achieved by varying the slot parameters, position, and radius of feed probe. Experiments have been carried out with good agreement with simulated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2021–2024, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21844 [ABSTRACT FROM AUTHOR]

Different methods to increase the bandwidth of a microstrip antenna, such as use of an air-gap in-between stacked resonators and the ground plane and planar multiresonators, are combined to achieve broad bandwidth with increased gain. A configuration with two gap-coupled circular microstrip antennas on the top dielectric layer stacked with one coaxial-fed circular patch on the bottom layer and an air-gap in-between two layers and the ground plane yield a bandwidth of 1093 MHz (47%) with a gain of 9.54 dB at the S-band frequency of 2.325 GHz. Also, dual-band response with broadside radiation and improved gain at both frequencies is achieved by suitably changing parameters of this configuration. Parametric studies of this configuration on dielectric substrate for both broadband and dual-band operation are presented in this paper. The experiments are performed on broadband and dual-band configurations, which are in agreement with the theoretical results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 489–494, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21208 [ABSTRACT FROM AUTHOR]

The NASA AE8 models are compared with 4 years of CEASE data from the TSX-5 satellite, with a focus on the radiation belt slot region. The current 4 years of the TSX5 mission is divided into solar cycle phase, with CEASE models developed for the solar maximum and declining phases. It is found that the AES models predict slot fluxes that are orders of magnitude less than that observed by TSX5/CEASE. [ABSTRACT FROM AUTHOR]

The multiport network model (MNM) has been used for analyzing a semicircular microstrip antenna (SCMSA) with a new method of determining the effective dielectric constant and loading the radiation resistance around the periphery to account for the radiation. The results obtained using this model for the fundamental and higher order modes of an SCMSA are in good agreement with the experimental results. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 237–241, 2001. [ABSTRACT FROM AUTHOR]

This paper describes a broadband planar rectangular monopole antenna. Both theoretical and experimental investigations have been carried out to draw an analogy between this monopole antenna and a rectangular microstrip antenna. Parametric studies have been carried out to optimize the bandwidth of the planar rectangular monopole antenna. There is good agreement between the theoretical and experimental results. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 55–59, 2001. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed a circular microstrip antenna with stubs using improved linear transmission line model. Tuneability and dual-band frequency performance of the microstrip antenna; Radiation patterns; Conclusions.

A technique of loading shorting posts on the patch has been used to enhance the directivity of a circular microstrip antenna (CMSA) in this paper. The shorting posts connected between the patch and the ground plane, force the electric field to become zero at that point, thereby modifying various modes of the circular patch. The shorting posts, also perturb the surface current distribution on the patch that help to increase its electrical size, which – in turn – enhances directivity at fixed resonance frequency. Investigations on various radii and positions of the shorting posts – to enhance the directivity of a CMSA, have been carried out. A systematic analysis on the performance of the CMSA at a lower order mode, fundamental mode and higher order mode frequencies with the loading of shorting posts has also been presented. The simulated and measured results show that the directivity of CMSA can be enhanced by up to 2 dB using the proposed technique without changing the patch geometry. In addition, the proposed antenna configuration yields, a bandwidth enhancement of almost three times as compared to that of a conventional CMSA. The simulated results of the conventional and shorted CMSA are experimentally validated with good agreement. [ABSTRACT FROM AUTHOR]

A generalized method is proposed to determine the effective dielectric constant and edge extension for predicting the resonant frequency of various microstrip antennas (MSAs) by equating their area with that of the equivalent rectangular microstrip antenna (RMSA). The theoretical frequency obtained using the present method is in very good agreement with the reported/measured frequencies. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 114–117, 1999. [ABSTRACT FROM AUTHOR]

Two new configurations of circular wire mesh and annular ring monopole antennas have been investigated and the results are compared with the corresponding circular disc monopole antenna. For the wire mesh monopole antenna of diameter 26 cm with peripheral metal strip, the measured bandwidth for voltage standing wave ratio ≤ 2 has been obtained from 258 to 5240 MHz, which has a bandwidth ratio of 20.3:1. For annular ring monopole with outer diameter of 26 cm and inner diameter 14 cm, the measured band width for voltage standing wave ratio ≤ 2 has been obtained from 245 to 5275 MHz leading to 21.5:1 bandwidth ratio. These new configurations have less wind loading and weight as compared to circular disc monopole antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2459–2461, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21977 [ABSTRACT FROM AUTHOR]

Compact gap-coupled shorted 90° sectoral microstrip antennas (MSAs) have been proposed, whose bandwidth is 2.5 times the bandwidth of the corresponding circular MSA (CMSA) with half the area. By partially shorting the 90° sectoral MSA, the broadband response is obtained at a lower frequency, leading to a further area reduction. Tunable dual-band operation has been obtained by increasing the coupling between the two patches using a shorting strip for both a single-short and a fully shorted 90° sectoral MSA. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 143–145, 2000. [ABSTRACT FROM AUTHOR]

Abstract: Half‐hexagonal microstrip antenna (H‐HMSA) is a compact version of HMSA, as it resonates at the same fundamental mode frequency. In this article, a compact configuration of a single layer, broadband gap‐coupled H‐HMSA has been proposed. Gap‐coupled H‐HMSA is fed indirectly by a λ/2 microstrip‐line resonator. Broad bandwidth (BW) is achieved with an effective use of resonance introduced by λ/2 resonator and gap‐coupled half‐hexagonal radiating patches. A peak gain of 7.07 dBi and measured BW (S11 ≤ −10 dB) of 11.5% at the center frequency of 5.2 GHz have been achieved, which occupies a small volume of 0.023 λ03 including the ground plane. The radiation patterns remain in the broadside direction throughout the return loss BW. Simulated results of the proposed antenna configuration are experimentally validated with good agreement. [ABSTRACT FROM AUTHOR]

Abstract: For the fundamental TM10 mode of an equilateral triangular microstrip antenna (ETMSA), along its height, the impedance value is maximum at the vertex, zero at the isocenter and finite value at the base. Along the base, the impedance remains constant in between 150 to 200 Ω, depending upon the design. Thus, 50‐Ω microstrip (MS) line cannot be used to directly feed an ETMSA at its base. Instead, either inset or impedance transformer is used to facilitate the 50‐Ω MS line feed. In this article, a simple MS line feed at the base is proposed using a single shorting post for impedance matching. By inserting a shorting post (via) closer to the edge of the base of an ETMSA, a wide range of impedances can be achieved at any of the edge by selecting proper shorting positions. A detailed investigation of an ETMSA with variation in shorting post position is carried out for the direct MS line feed. Experiments have been carried out to validate the concept. [ABSTRACT FROM AUTHOR]

A design technique of an antenna array with amplitude distribution/tapering to suppress the first side lobe level by exploiting the property of the rectangular microstrip antenna (RMSA) is proposed. Non-identical antenna array elements have been designed using the RMSAs by varying their width and hence the gain (keeping the length and hence the frequency same) to obtain the amplitude distribution for a desired first side lobe level. This eliminates the need of a complicated feed network with unequal power division to realize amplitude tapering. The conceptualized design is verified for a number of corporate-fed arrays and an analysis is carried out to give design guidelines with respect to the number of elements in the array. A symmetric corporate-fed 8-element antenna array with a cosine-square over pedestal amplitude distribution, operating at 1.8 GHz, has been designed and fabricated to validate the proposed concept. There is a reasonable agreement between simulated and measured results. [ABSTRACT FROM AUTHOR]

A modified printed square monopole antenna with semicircular base has been proposed, which gives ultra-wide bandwidth ratio of 11.31∶1. A frequency-dependent design curve, for the microstrip feedline, is presented for this modified configuration. Experiments have been performed to measure impedance bandwidth and radiation patterns of the monopole, which are in agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A new printed monopole configuration, the vertex chopped printed triangular monopole antenna, is proposed. It gives an ultra-wide impedance bandwidth ratio of 12.6:1 for a voltage standing wave ratio of 2 and over 25:1 for a voltage standing wave ratio equal to 2.6. Experiments were performed to measure the bandwidth and the radiation patterns of this antenna, which tally well with simulated results. [ABSTRACT FROM AUTHOR]

The main feature of an antenna array is its ability to form and scan the shaped main beam by using the amplitude and phase inputs as the controlling parameters at element level. In this paper, a comprehensive analysis of various parameters of a uniformly spaced linear array with respect to a number of elements for different amplitude distribution/window functions has been presented. There is a general assumption that any given window function will realize the expected parameters of the array even for a small number of array elements. A systematic study has been done to bring out very clearly the minimum number of elements that is required to realize antenna performance for a particular amplitude distribution. Effect of number of elements to obtain the desired first side lobe level and efficiency is presented. Contributions have been made to discuss the effects on directivity, gain, and beamwidth of the linear array. [ABSTRACT FROM PUBLISHER]

The broadband and dual-band rectangular microstrip antenna is realized by cutting pair of toothbrush-shaped or step slots along the non-radiating edges of the patch. The toothbrush-shaped slot is said to introduce TMd0 mode in between the TM10 and TM20 modes of the rectangular patch and realizes broadband response. In step slot cut configuration, the slot introduces a mode near the TM10 mode resonance frequency of the patch and realizes dual frequencies. In this paper, a detail analysis to study the effect of slots on the broadband and dual-band response in these rectangular microstrip antennas (RMSAs) is presented. It was observed that the slot does not introduce any mode but modifies the resonance frequency of higher order orthogonal mode and realizes broadband and dual-band response. The slot alters the direction of surface currents at higher order mode and gives similar radiation pattern characteristics over the broader bandwidth and at the dual frequencies. In broadband RMSA, a formulation of resonant length at modified TM02 mode is proposed. The frequency calculated using the same closely agrees with the simulated result. [ABSTRACT FROM AUTHOR]

Wideband designs of rectangular microstrip antennas embedded with three rectangular slots are proposed. These slots modify resonance frequencies of patch's TM10, TM02 and TM11 mode, to give bandwidth of more than 500 MHz (50%). Further, pair of slots cut variations of rectangular patch with three slots is proposed. Additional pair of slots tune the next higher order TM12 mode frequency with respect to modified lower order resonant modes, resulting in further increase in bandwidth of more than 600 MHz (> 55%). Increased bandwidth obtained in the proposed designs is more than that obtained from equivalent E-shape and U-slot cut patches. As compared with Ψ-shape patch antenna, the proposed configurations yield wider bandwidth with 38% reduction in patch size. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel design of broadband CPW-fed star shape patch antenna backed by rectangular ring ground plane is proposed. The star shape patch realized by combining two triangular shape patches, yields bandwidth of more than 5 GHz (>130%). Over the bandwidth, proposed antenna shows broadside radiation pattern with a peak gain of 3 dBi. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2443-2450, 2016 [ABSTRACT FROM AUTHOR]

A frequency-reconfigurable slot antenna using metasurface (MS) is proposed. Two identical anisotropic MS layers are loaded on top of a slot to achieve the frequency reconfigurability. The MS layer is composed of a periodic arrangement of I-shaped metallic inclusions placed in both the horizontal and vertical directions. The MS layers are fed by a linearly polarized slot antenna. The operating frequency of the proposed antenna is tuned by physically rotating the two MS layers with respect to the centre of the slot antenna. Rotation of the MS layers changes the effective permittivity and the loading on the slot antenna and hence the operating frequency changes. The proposed antenna has a low profile with the thickness of the antenna including the two MS layers being 0.07\lambda0. The simulated and measured results show that using the proposed technique, the operating frequency can be tuned from 2.55 to 3.45 GHz with a fractional tuning range of around 28%. The antenna provides a minimum gain of 5.3 dB with the peak gain being 8.3 dB. The efficiency of the proposed antenna is more than 90% over its tuning range. [ABSTRACT FROM AUTHOR]

Presents an experimental study on circular disc monopole (CDM) antennas including some configurations such as elliptical disc with different ellipticity ratios, square, rectangular and hexagonal monopoles. Fabrication of the elliptical disc monopole (EDM); Radiation pattern of CDM and EDM; Conclusions.

A composite design of Band Pass Filter (BPF) is developed with 3-dB fractional bandwidth (FBW) of more than 140%. This BPF is suitable for the development of wideband radar, communication and EW system in 1 to 6 GHz. Composite BPF design utilizes stepped impedance Low Pass Filter (LPF) along with the quarter wavelength (λg/4) short circuited stub. λg/4 short circuited stubs incorporated High Pass Filter (HPF) response which transforms overall design into BPF. Four cases of filter have been discussed. In case-I, the proposed BPF is developed with a size of 32.6 mm X 7.0 mm. Further in case-II, design has been realized with improved roll-off at the lower edge of the bandwidth (i.e., 1GHz). In case-III, developed design is 75% length-wise miniaturized that of case-I. Further in case-IV, about 55% length-wise miniaturization is done. Case-III and IV have their response similar to that of the case-I with miniaturized design. All designs are simulated, optimized and fabricated over RT-Duroid 5880 substrate. For case-I, III and IV fabrication has been done on 20 mil thick substrate, whereas for case-II 31 mil thick substrate is used. Comparisons between all the cases have been presented in tables and S-parameter plots. [ABSTRACT FROM AUTHOR]