In this paper, a compact, dual-band patch antenna is proposed over Minkowski fractal defected ground structure (DGS) for bandwidth enhancement of global positioning system (GPS) applications. The proposed design combines the truncated dual L-shaped slits cut on diagonal corners of radiating patch and fractal defect on the metallic ground plane. This concept shifts the frequencies to lower bands with improvement in antenna radiation properties. By deploying symmetrical and asymmetrical boundaries to the structure for the fractal DGS on metallic ground plane, improvement in bandwidth and gain are obtained. Compact antenna size is achieved for dual-band GPS frequencies of L1 (1.575 GHz) and L2 (1.227 GHz). The measured results for antenna prototype are (1.2–1.245 GHz): L2 band and (1.51–1.59 GHz): L1 band for 10 dB return loss bandwidth with better pattern radiation. Gain value with and without DGS is observed for compact antenna overall volume of 0.32λ0 × 0.32λ0 × 0.024λ0.

In this paper, a coplanar waveguide (CPW)-fed dual-band uniplanar tri-polarization reconfigurable antenna based on the PIN diode switch is proposed. The proposed antenna can be reconfigured between the linear polarization (LP) and the circular polarization (CP) mode, including both the right-handed circular polarization and left-handed circular polarization simultaneously within the dual operating bands. The central frequencies of the bands are 2.63 and 4.42 GHz, respectively, and the overlapped operating bandwidth is 17.8 and 3.40%. The proposed reconfigurable antenna is a closed-slot antenna fed by the CPW transmission line and the reconfigurable mechanism is to regulate the T-shaped driven stub through switching the PIN diodes on and off. The scattering parameters, axial ratio, radiation pattern, gain, and the radiation efficiency of the proposed antenna are all investigated in the following. The optimized antenna has been fabricated to experimental test, the simulated and the measured results agree well with each other. The lower frequency band of the proposed antenna covers the 2.40 GHz WLAN specification and the upper band can be used for the 5 G communication (4.40–4.50 GHz); therefore it is suitable to be applied in the mobile wireless communication.

A probe feed wideband multi-element dual segments quarter cylindrical dielectric resonator antenna (q-CDRA) in composite forms have been proposed. The q-CDRA has been introduced by splitting CDRA into four uniform quarters and multi-segmentation approach has been castoff for further improvement in bandwidth of q-CDRA. The dual segments q-CDRA has been designed and analyzed using theoretical analysis and Ansoft HFSS simulation software. Further the dual segment multi-element q-CDRAs in composite form have been designed. A coaxial probe has been placed at the center of the ground plane for the excitation of proposed multi-element and multi-segmented composite form of q-CDRA, which excite TM01δ mode in the proposed antenna. The input characteristics and radiation patterns of the proposed composite antennas have been studied and their results are compared with corresponding experimental results. Prototype of single, two, and four elements dual-segment composite q-CDRAs have been fabricated and input characteristics of the proposed composite antennas have been compared with each other. Four elements dual-segment composite q-CDRA has shown wide impedance bandwidth (|S11| ≤ −10 dB) of 85.13% with monopole-like radiation pattern. The peak gain of 4.85 dBi with 98.5% radiation efficiency has been achieved for dual-segment four elements composite q-CDRA. The proposed multi-element dual-segment composite q-CDRAs may find suitable applications in C and X-band with complete covering of the 5.0 GHZ wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) band.

In this paper, an asymmetric coplanar strip (ACS)-fed quad-band monopole antenna for the global positioning system (GPS), wireless local area network (WLAN), and worldwide interoperability for microwave access (WiMAX) applications is proposed. It is composed of an F-shaped monopole and a partial ground plane, which are both printed on one side of a low-cost FR4 substrate with a compact volume of 40 × 20 × 1.6 mm3. By cutting an open-ended Γ-shaped slot into the F-shaped monopole, four distinct resonant modes are successfully generated. The design process, especially the geometrical configuration of the critical Γ-shaped slot is studied in detail. The proposed antenna has been fabricated and experimental results show that the −10 dB impedance bandwidth can fully cover the 1.575-GHz GPS (1.57–1.59 GHz), 2.4/5.2/5.8-GHz WLAN (2.4–2.485, 5.15–5.35, and 5.725–5.825 GHz), and 2.5/3.5/5.5-GHz WiMAX (2.50–2.69, 3.30–3.70, and 5.25–5.85 GHz) applications with nearly omni-directional radiation patterns and satisfactory gains.

In this paper, an array antenna with asymmetric antenna fed network is presented. Total size of the proposed array antenna (with 2 × 2 elements) is 90 × 90 mm2 and distance between elements (fed by fed) is λ0/2 (λ0 = wavelength in free space). The proposed antenna is fed by coaxial cable that isolated input impedance from impedance of the array antenna feed network. The measured impedance bandwidth of the coaxial fed circular polarization array (S11 < −10 dB) is 47.9% from 4.6 to 7.5 GHz (1.63:1), and the measured 3-dB axial-ratio bandwidth is 42% from 4.7 to 7.2 GHz. The peak gain of antenna is 9.1 dBic.

In this paper, combination of electromagnetic band gap (EBG) and split-ring resonator (SRR) loads with fractal formation for miniaturization of microstrip antenna is noticed. Here two different shapes of antenna have been studied with two well-known metamaterial structures as parasitic elements. A conventional microstrip antenna, which is surrounded by four EBG unit cells, is chosen as the first antenna. It has an effective resonance at 2.5. The Minkowski fractal method is applied to EBG unit cells in this stage. The Minkowski fractal structure is implemented for accession of effective capacitance in EBG unit cells. The second antenna frequencies are 2.5 and 5.9 GHz. It contains a slot structure with four SRRs, used for making parasitic elements and for achieving multi-band characteristic. The fractal method is used to improve the inductance of SRR structure by increasing the effective length of microstrip line. At this stage, the applied fractal structure has been modified, so that the frequency of wireless application could be achieved. In the last step, by some changes in feed line of the slot antenna, circular polarization (CP) is obtained for the second antenna, which shows that SRR load can be helpful for making the CP.

In this study, a dual-layered polarization and frequency reconfigurable microstrip antenna is proposed based on sequential mechanical axial rotation of the circular metal radiator. The antenna can be reconfigured among three different polarized modes, including the linear polarization (LP), left-handed circular polarization and right-handed circular polarization in the band from 4.68 to 4.80 GHz (2.53%). The resonance frequency of the proposed antenna with the same LP mode could also be tuned in the range from 4.70 to 5.03 GHz by mechanical rotation of the breach-truncated circular metal radiator as well as the circular substrate. Furthermore, the polarization characteristic and frequency can be reconfigured, respectively, as the circular radiator is taken an axial rotation with an angle of 360°. The presented antenna in the four different states has been numerically simulated and fabricated for the experimental measurement, the investigated characteristics includes the port reflection coefficient, axial ratio, radiation pattern, gain, and the radiation efficiency. The simulated and test results agreed well with each other. This antenna enriches the novel mechanical reconfigurable method except for the popular electrical approach.

This paper presents an original solution to design a compact dual circularly polarized isoflux antenna for nanosatellite applications. This kind of antenna has been previously designed in our laboratory, for a single circular polarization. This antenna is composed of a dual circularly polarized feed and a choke horn antenna. This feed is a cross-shaped slot in the ground plane, which provides coupling between a patch and a ring microstrip line with two ports. It is located at the center of a choke horn antenna. The simulated antenna presents an axial ratio <3 dB and a realized gain close to 0 dB over a 400 MHz bandwidth (8.0–8.4 GHz) at the limit of coverage, i.e. 65° whatever the azimuth angle (φ) and the port. A 20 dB matching for each port and 13 dB isolation characteristics between the two ports have been achieved on this bandwidth. It has been realized and successfully measured.

In this paper, a novel design and experimental study of microstrip-line-fed rhombus-shaped slot antenna is presented. The proposed antenna shows an ultra-wide band (UWB) operation with good impedance matching by choosing appropriate rhombus-shaped slot and feeding structure. The proposed antenna has a simple structure and compact size as compared with many reported antennas. The measured results validate the design and the impedance bandwidth can operate from 2.78 to 12.92 GHz (10.14 GHz), which evidently covers entire UWB (3.1–10.6 GHz). Furthermore, the key parameters of the antenna are also discussed to study their persuade on the antenna performance.

A novel quarter cylindrical dielectric resonator antenna (q-CDRA) has been introduced by splitting four uniform quarters from a cylinder. q-CDRA has been designed and validated with theoretical analysis. Two and four element q-CDRAs have been proposed in composite forms through Ansoft high-frequency structure simulator simulation software and fabricated for experimental investigation. The input characteristics and radiation patterns of the proposed antennas have been studied through simulation and compared with the measured ones. The |S11| characteristics of the proposed antennas have been compared with each other. The four-element composite q-CDRA has wide impedance bandwidth (|S11| ≤ −10 dB) of 58.15% with monopole-like radiation pattern as compared with other q-CDRAs. The two and four elements q-CDRAs have symmetric monopole-like radiation patterns with linear polarization for whole operating bandwidth (4.5–8.6 GHz). The proposed composite q-CDRAs may find suitable applications in WLAN and WiMAX band.

In this paper, compact single-feed dual-band antennas for different wireless applications are proposed. First, a dual-band antenna with a comparatively large frequency ratio of 2.58 is designed. Then, a novel dual-band antenna is introduced in order to enhance the upper frequency band. The technique consists of modifying the feed line structure, which leads to a 9.23% of impedance bandwidth at the central frequency of 6.5 GHz instead of 2.06%. The designed antennas are fabricated and tested in the laboratory and in a small anechoic chamber in order to measure their reflection coefficient, gains, and efficiencies. Good agreement between simulated and measured results is obtained. The designed antennas are particular because they have low profile, very simple single-feed technique, can be designed for large frequency ratios, and also the bandwidth can be clearly enhanced. Therefore, they can be used for different wireless applications.

The design and analysis of meta-material inspired loaded monopole antenna for multiband operation are reported. The proposed antenna consists of multi resonators inspired from half mode composite right/left handed cells, which has a simple structure, compact size, and provides multiband functionalities. As a proof of concept, a triple band antenna covering all possible WiMAX operating bands, has been designed, fabricated, and characterized. The hosting monopole patch itself generates resonance for 3.3–3.8 GHz band, whereas the loaded metamaterial cells add extra resonance frequencies. The loading of two resonator cells introduces two extra resonances for 2.5–2.7 GHz and 5.3–5.9 GHz bands, respectively. The antenna's operating principle and design procedures with the aid of electromagnetic full wave simulation and experimental measurements are presented. The antenna has good omnidirectional patterns at all three bands. The monopole patch size is 13.5 × 6.5 mm2 and the whole antenna size (including the feed line) is 35 × 32 mm2. Compared with conventional single band microstrip patch radiator, the radiator size of this antenna is only 8.5% at 2.5 GHz, 17% at 3.5 GHz, and 37% at 5.5 GHz.

In this paper, the concept of perturbation theory is applied to derive a general electric field (E-field) expression for any arbitrary-shaped microstrip patch antenna. The arbitrary shape is created by adding small perturbation in a regular patch shape, which is used to find perturbed and unperturbed electromagnetic wave solutions for resultant E-field of patch antenna. Ansoft HFSS simulator is used to validate the derived field expression in curvilinear coordinates for a regular circular-shaped patch. Then the proposed field analysis is applied to develop two new arbitrary-shaped patches in C-band for desired E-field patterns.

A 4–8 GHz ultra wide band microstrip array antennas with improved gain for weather Radar applications was designed and fabricated. The microstrip radiating elements of the proposed array antennas are powered using a T-junction power divider with quarter wave-transformer impedance for a best matching. The design of this array antennas is based on the geometry of a linear array antennas well studied [ref (8)], which is based on minimizing of the electromagnetic (EM) coupling between the radiating elements and as decreasing the number of side lobes. The array antennas with dimension of (110 × 214 × 1.58 mm3) is fabricated on FR-4 epoxy dielectric with relative permittivity of 4.4 and thickness h = 1.58 mm, it is performed in the full-wave EM solver High Frequency Structure Simulator, CST and verified by measurement. The proposed broadband array antennas show a better performance than the references antennas in deferent parameter which cited after.

In this paper, a frequency reconfigurable microstrip slot antenna for ultra-wideband applications with switchable band-notch functions is designed and manufactured. To generate a wide usable fractional bandwidth of 3 to over 13.6 GHz, square patch transforms to a fork-shaped patch, also two triangular-shaped strips have been added at above sections of rectangular slot on the ground plane. Band rejections are obtained by adding two inverted L-shaped strips in the fork-shaped patch and one L-shaped defected ground structure. Moreover, by implementation of two PIN diodes within the antenna structure, four switchable frequency responses are achieved. The designed antenna has simple structure and a small size of 20 × 20 × 0.8 mm3 while providing band rejection characteristics at WiMAX (Worldwide Interoperability for Microwave Access) and WLAN (Wireless Local Area Networks) systems.

In this paper, a wideband two-segmented four-element triangular dielectric resonator antenna (TDRA) with coaxial probe feed has been proposed. The proposed antenna has been analyzed, optimized, and studied through Ansoft HFSS simulation software. The prototype of the proposed antenna has been fabricated and its input characteristics are measured with the help of R&S Vector Network Analyzer. Good agreement has been obtained between simulated and measured results. The proposed design has been compared with two segments TDRA and found wider bandwidth with lower resonant frequency. The proposed antenna provides monopole-like radiation pattern over the entire bandwidth with nearly 33% bandwidth (return loss ≥10 dB) at a resonant frequency 6.9 GHz and 4.93 dBi peak gain. The proposed antenna is suitable for application of C-band microwave frequencies.

A low-profile circularly polarized (CP) slot antenna to achieve a wide axial-ratio (AR) beamwidth is proposed in this paper. The radiating patch consists of two orthogonal pairs of parallel slots etched symmetrically onto a ground plane. Firstly, our theoretical study demonstrates that the CP radiation can be satisfactorily achieved at the broadside, when the vertical and horizontal paired-slots are excited in the same amplitude with 90° phase difference. Secondly, the principle of CP radiation of the proposed antenna on an infinite ground plane is described. Through analyzing the spacing between two parallel slots, the |Eθ| and |Eφ| radiation patterns can be made approximately identical with each other over a large angle range. As such, the slot antenna achieves a wide AR beamwidth. After that, the 3 dB AR beamwidth with respect to the size of a finite ground plane is investigated to constitute a practical CP antenna on a finite ground plane. In final, the proposed CP antenna with a 1–4 probe-to-microstrip feeding network is designed and fabricated on a finite ground plane of a dielectric substrate. Measured results are shown to be in good agreement with the simulated ones about the gain, reflection coefficient, AR bandwidth, and radiation patterns. Most importantly, a wide 3 dB AR beamwidth of 126° and low-profile property with the height of 0.036λ0 are achieved.

In this paper time modulated nine-ring concentric circular antenna array (TMCCAA) using fitness based novel hybrid adaptive differential evolution with particle swarm optimization (ADEPSO) has been studied. ADEPSO is hybrid of fitness based adaptive differential evolution and particle swarm optimization (PSO). Differential evolution is a simple and robust evolutionary algorithm but sometimes causes instability problem; PSO is also a simple, population based robust evolutionary algorithm but has the problem of sub-optimality. ADEPSO has overcome the above individual disadvantages faced by both the algorithms and is used for the design of TMCCAA. The comparative case studies as Case-1 and Case-2 are made with three control parameters like uniform inter-element spacing in rings, inter-ring radii and the switching “ON” times of rings. The same array radiates at various harmonic frequencies. The first two harmonic frequencies have been considered in this work. The numerical results show Case-2, outperforms Case-1 with respect to better side lobe level (SLL), and more improved directivity. Apart from this, the authors have computed powers radiated at the center/fundamental frequency and the first two sideband frequencies, and dynamic efficiency. It is found that power radiated by any sideband frequency is very less as compared with the power radiated at the center frequency. It has been observed that as the sideband frequency increases, side band level decreases to the greater extent as compared with SLL. The aperture size is a very important constraint for the array, since there is an upper limit for the aperture size of a given array in real-life environment. Hence, in our optimization design, the maximum radius of the concentric ring array is constrained.

This paper proposes a novel wideband to concurrent tri-band frequency reconfigurable microstrip antenna. The frequency reconfiguration is achieved by using a pair of PIN diodes in the antenna feed line to switch the antenna either in wideband mode or in concurrent tri-band mode. In order to improve the bandwidth and gain of the antenna for wideband operation, the properties of J-K inverter and split ring resonators are exploited. To demonstrate the versatility of this concept a prototype is fabricated and tested here. The tested results in wideband mode shows that the proposed antenna operates from 3.58 to –3.82 GHz, which is 4.08 times larger than the bandwidth of a simple microstrip patch antenna. In the concurrent tri-band mode frequency tuning is done by microstrip open stub at 1.5 GHz, 1.9 GHz, and 3.5 GHz. Gain of the proposed antenna is better than 2.7 dB in wideband mode and 2.7 dB in concurrent tri-band mode.

Owing to dynamic nature of vehicular environments, it becomes essential to achieve effective communication via vehicle-to-vehicle and infrastructure-to-vehicle. This leads to the need for an antenna system that supports multiple frequency bands, high gain, broadside radiation pattern, and circular polarization. We propose single-arm penta-band-based spiral antenna with dimensions of 51 × 35 × 1.574 mm3 resonating at navigational wireless frequencies 1.2 GHz for IRNSS and 1.5 GHz for GPS; wireless communication frequencies 2.45 and 3.3 GHz and dedicated short range communication frequency 5.8 GHz. Linear taper feed has been introduced to achieve good impedance matching and the outer edge feed of the spiral on the same plane helps to achieve circular polarization. The measurement result proves the betterment in impedance of the spiral antenna that varies from 50 –55 Ω across the desired operating frequencies.