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.

With quad-band-notched characteristic, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna is introduced in the paper. The UWB–MIMO system has two similar monopole elements and occupies 30 × 45 mm2. By inserting two L-shaped slots, CSRR and C-shaped stubs, four notched bands are achieved (3.25–3.9, 5.11–5.35, 5.5–6.06, and 7.18–7.88 GHz) to filter WiMAX, lower WLAN, upper WLAN, and X-band. Meanwhile, the isolation is obviously enhanced with three metal strips on the ground plane. Results indicate that the antenna covers UWB frequency band of 3.1 – 10.6 GHz except four rejected bands, isolation of better than −18 dB, envelope correlation coefficient of <0.02, and good radiation pattern, thus making it useful for UWB systems.

A novel dual-band single-feed reconfigurable annular-ring slot antenna with polarization diversity is proposed. This antenna has the ability to switch frequency bands and polarization at the same time whereas applying a simple structure. It consists of two concentric circular slots and two tuning stubs on one side of the substrate and a 50 Ω microstrip feed line and two stubs on the other side. The proposed antenna can be switched between two resonant frequencies, 2.4 GHz (WLAN) and 3.5 GHz (Wimax). Furthermore, it can be switched between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) at the first frequency band, LHCP and RHCP at the second band. All these capabilities are achieved by applying only five PIN diodes on both sides of the substrate. Simulation and experimental results indicate that the proposed antenna demonstrates a good impedance bandwidth at the two frequency bands and satisfactory radiation pattern in five different states.

This paper presents a miniature monopole reader antenna for tri-band radio frequency identification (RFID) portable devices. The proposed antenna operates at the main RFID frequencies and can alleviate and compensate for the shortcomings of a single-band antenna. An additional rectangular stub couples with the bent monopole antenna, allowing the latter to resonate at the RFID bands at 902–928 MHz, 2.4–2.48 GHz, and 5.725–5.875 GHz. By bending the feedline, the dimensions of the miniature antenna are reduced to 115.5 × 20 × 1.6 mm3, facilitating its integration into portable devices. The measured bandwidths(return loss < −10 dB) of the proposed antenna are 677, 580, and 250 MHz in the three operating bands, 883–1560 MHz, 2.31–2.89 GHz, and 5.65–5.9 GHz, respectively, with high-gain characteristics. An experimental study of a fabricated prototype of the optimized antenna is performed, and the results verify its good performance.

Artificial neural networks (ANNs) have acquired enormous importance in computing of the performance parameters of microstrip antennas due to their generalized and adaptive features. However, recently the concept of support vector machines (SVMs) has become very much popular in performance parameters computation due to several attractive features over ANNs. Specifically, SVMs outreach ANNs noticeably in terms of execution time. Likewise, ANNs are having multiple local minima problem, whereas a global and unique solution is provided by SVMs. In this paper, several performance parameters like: resonant frequency, gain, directivity, and radiation efficiency of slotted microstrip antennas with modified ground plane are computed with the help of SVM formulation. Comparisons of different parameters of simulated and computed values are illustrated. The achieved radiation patterns at particular resonant frequency in different planes are included as well. A prototype of the optimized antenna is also fabricated and characterized. A good agreement is attained among the computed, simulated, and measured results.

In this work, microstrip antenna with W- and V-shaped radiating patches have been proposed. Here square- and circular-shaped modified ground planes have been designed by poly tetra fluoro ethylene (PTFE) substrate with dielectric constant 2.4. Broadband with high gain is obtained by optimum selection of radiating patch with modified ground plane. The ground planes are modified by loading a U-shaped slot. The simulated and measured results are compared. Considering −10 dB impedance bandwidth maximum frequency band of 6.97 GHz (3.04–10.01 GHz) with percentage bandwidth of 106.8% is achieved. The proposed antenna exhibits maximum peak gain of 5.1 dBi. The simulation and measurement have been done by Ansoft designer software and vector network analyzer.

In this paper, a miniaturized CPW-fed tapered slot antenna (TSA) with a modified CPW to slot-line transition structure was introduced. An air-bridge and tapered slot edge (TSE) structure was also employed to broaden the transition bandwidth. Through these applied modifications, negative features of the original TSA (limitation of transition) and antipodal Vivaldi antenna (bad cross-polarization) are both removed, while all the positive features remained. Results showed that the proposed structure offered a broad bandwidth of 2.6–20 GHz and also exhibited an appropriate current distribution with high radiation efficiency. The radiation pattern was stable in the working frequency band with good directivity, gain, and low cross-polarization. The proposed antenna structure also presented satisfactory time-domain characteristics. In this study, we confirmed the simulation results through data measurements.

A compact size hybrid fractal antenna is proposed for the application in wideband frequency range. The proposed antenna structure is the combination of Koch curve and self-affine fractal geometries. The Koch curve and self-affine geometries are optimized to achieve a wide bandwidth. The feed circuit is a microstrip line with a matching section over a rectangular ground plane. The measured impedance matching fractal bandwidth (S11 ≤ −10 dB) is 72.37% from 1.6 to 3.4 GHz. An acceptable agreement is obtained from the simulated and measured antenna performance parameters.

In this study, a dual-wideband monopole antenna has been designed and developed for the universal mobile telecommunications system (UMTS), wireless local area network (WLAN), and worldwide interoperability for microwave access (WiMAX) applications. A novel approach integrating artificial bee colony (ABC) with the HyperLynx® 3D electromagnetic platform based on the method of moments has been employed to calculate the design parameters of the monopole antenna performance for the respective target frequencies and return loss. The proposed dual-wideband antenna operates in the dual-frequency ranges of 1.69–3.99 and 4.75–6.22 GHz applicable for the UMTS, WLAN, and WiMAX applications and it is fabricated on the flame resistant-4 substrate plate of 42 × 51 × 1.6 mm3. The performance of the presented monopole antenna is analyzed in terms of gain, radiation pattern, and s-parameter. The input reflection coefficient (S11) parameter and radiation pattern of the antenna are verified through the measurements. The measured values of the antenna parameters are found to match well within tolerable limits with the simulation results. The results illustrate that the presented dual-wideband monopole antenna obtained by using the ABC algorithm exhibits better performance in point of operating bands and s-parameter as compared with the multi-band antennas previously published in the literature.