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A circularly polarized high gain hybrid rectangular patch/horn antenna with chamfered corners is presented in this paper. The measured impedance bandwidth of the proposed design extends from 26.7 to 28.7 GHz. The suggested design antenna exhibits circular polarization propagation over the working band, which is achieved by introducing chamfered corner overlapped patch antennas surrounded by the truncated pyramidal horn. The main purpose of this horn is to enhance the overall gain without any deterioration of other antenna characteristics (more than 4 dB over the operating band when compared to the patch antenna). The maximum measured gain of the hybrid antenna is 10.9 dBi. The radiation patterns of the hybrid antenna show directive broadside radiation with stable performance over the whole frequency band. The suggested antenna is analyzed and designed applying both the numerical simulator (CSTMWS and HFSS). [ABSTRACT FROM AUTHOR]

This article presents the design and implementation of a beam-steering antenna array using a 4×4 Butler matrix feed network (BMN) for 5G applications. The proposed antenna array can achieve a gain of 14 dBi and a steering range of (+16°, -47°, +46.5°, -15.7°) to cover angular range extending from 45° to 135°. To achieve that, a simple, 4 × 4 Butler matrix etched on a single-layer microstrip structure is designed, optimized, and fabricated. The proposed design incorporates phase shifters, 3-dB couplers, and cross-over couplers. The proposed matrix is employed as a feeding network for 4-element wideband LPDA antenna array. The fabrication results of the feeding matrix and antenna array show very good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

Extensive work had been conducted on spot-welding due to its rapidly increasing industrial importance. The resistance spot-welding involves complicated phenomena, as several effects are found in the process, e.g., temperature, surface roughness, pressure, and eddy current effects. Most of the work exerted for analyzing the spot-welding process neglect the effect of the eddy current generated during the flow of the huge welding main current through the assembly of electrodes and work sheets. This work presents an analytical method to investigate the generation of eddy current and to determine the total effective welding current in spot-welding. The current distribution on the work sheet when it is .fed by a conducting electrode is also investigated. The obtained current formula is based on electromagnetic principles, where a very strong magnetic field is generated in the core of the electrodes as well as in the materials of work sheets due to the flow of very. high amperage. The final resultant effective current is the superposition of the electrode welding current and the induced eddy current in the electrode and work piece assembly. The results offer a viable mathematical model, which can be applied for a precise prediction of the effective value of welding current in spot-welding processes, if applied in a comprehensive model including all involved effects. Keywords: resistance spot-welding, welding current, eddy current, effective current distribution, magnetic fields [DOI: 10.1115/1.4000434]

A time domain analysis of an optically controlled digital microstrip switch for microwave integrated circuits on Si substrates is studied. A new model for high-frequency pulse propagation on a microstrip optical switch for different optical parameters is presented. A frequency-dependent macromodel for a microstrip line with a gap is implemented in SPICE3, taking into consideration high-frequency pulse dispersion, conductor and dielectric losses, metallization thickness, gap length, and different optical parameters such as optical energy, surface recombination velocities, and diffusion of generated carriers. In addition, the developed model has been used to optimize the switching frequency, gap length, level of optical power, and suitable substrate material parameters.

A detailed analysis of a microwave reflection pattern that is due to periodically photoexcited layers of semiconductor material in a waveguide is presented. Different photoconductivity profiles that are due to different excitation conditions with different materials are tested. The diffusion of carriers in the direction of propagation can strongly affect the passband-filtering responses, especially the efficiency and the bandwidth. These configurations can be used as light-induced tunable filters and as a variable matching section between different levels of impedances.

This paper presents a new optically controlled reconfigurable ultra-wideband antenna using reconfigurable optical router with photonic crystal substrate. The proposed antenna has three optical switches. The optical switches are made by placing silicon wafers over three slots etched on the resonator. The coplanar fed microstrip antenna can work at eight modes using optically controlled switches. This design proposes triple narrow notched bands at center frequencies 3.5 GHz “WiMAX”, 5.5 GHz “WLAN” and 8.4 GHz “X-band satellite communication”. The proposed antenna satisfies the voltage standing wave ratio requirement of <2 in the frequency band between 2.6 and 11.8 GHz except for the three rejected bands. According to the incident light, the physical properties of these switches can be changed from an insulator state (OFF state) to a near-conducting state (ON state). The incident light is coupled to the optical switches using a reconfigurable optical router. The proposed antenna provides high gain, and high efficiency all over the frequency band excluding the rejected bands. [ABSTRACT FROM PUBLISHER]