Circular Ribbon Antenna Array Design For Imaging Application

Our goal is to develop THz module on chip to visualize bone grinding atthe early stage so that arthritis can be visualized and treated early. A criticalcomponent of such module is antenna. A compact 4 by 4 beamformingantenna array for biomedical application is presented in this paper. Weare proposing a novel antenna which is in the form of a circular ribbonshape with a gold patch. Gold material for the patch is used to enhance itsconductivity and to cut down backward radiation. Differential port pin usedto increase the bandwidth. Au-posts are finally used for output connection.The proposed antenna operates over the frequency band from 201 GHz tomore than 228 GHz. Directivity and gain of the proposed antenna are 13dB and 7 dB respectively. This makes it applicable for imaging systemsbecause of the frequency band for biomedical imaging. Index Terms—Beamforming antenna, antenna array, Advanced design system (ADS),Biomedical imaging.

Miniaturization and Electromagnetic Reliability of Wearable Textile Antennas

The wearable textile antenna plays a decisive role in the currently increasingly wireless communication network area. To realize the miniaturization and electromagnetic reliability, a slotted full-textile microstrip antenna was designed and fabricated using the screen printing method. The measured return loss and radiation pattern were tested and compared with the simulated results. Additionally, the adhesion between the silver paste coating as the radiation element and the textile substrate was detected using sticking tape as well as observation by the microscope. To develop the designed antenna in the on-body application, the artificial magnetic conductor (AMC) was designed, optimized and fabricated. The antenna performance results showed that the existence of the AMC had a significant effect in reducing the body coupling and antenna backward radiation.

Broadband, Beam-Steering Asymmetric Stacked Microstrip Phased Array with Enhanced Front-to-Back Ratio

The backward radiation is a critical problem that may cause breakdown of the front-end circuits that are integrated behind the antenna. Thus, antennas having high Front to Back Ratio (FBR) are required. For phased arrays, the back lobe suppression is required for all scanning angles at all frequencies of the band. In this work, a stacked patch linear array with asymmetric configuration is proposed. It is capable of scanning the beam in ±40° with less than 1.34 dB scanning loss. Due to the usage of probe-fed stacked patches as the antenna elements, impedance matching in 8-10 GHz is achieved. More than 30 dB FBR is obtained for broadside radiation. It is above 20 dB when the beam is steered to θ = 40°. This is valid for all frequencies of the band. A prototype is fabricated and measured. Higher than 38 dB FBR is observed. With its broadband, high FBR and low scanning loss, the proposed asymmetrical stacked patch phased array is suitable as radar and base station antenna.

Formation of Neutral Points in the Polarization Characteristics of Secondary Radiation in the Semi-Infinite Medium Model

This article studies the polarization characteristics of diffusely reflected backward radiation when illuminating a semiinfinite, light-scattering medium with unpolarized radiation. The formation of neutral Babine, Brewster and Arago polarization points in the angular polarization characteristics of the secondary radiation is shown. Comparison between the results of exact numerical calculations and approximate analytical formulas has been carried out and physical conditions for the appearance of neutral points depending on the angles of illumination and the multiplicity of scattering have been analyzed.

Ultra-Wideband Low-Cost High-Efficiency Cavity-Backed Compound Spiral Antenna

A low-cost high-efficiency ultra-wideband (UWB) cavity-backed spiral antenna is proposed. It employs an equiangular spiral enclosed by an Archimedean spiral and it is fed through a tapered microstrip balun. A center-raised cylindrical absorber-free cavity backs the spiral to minimize the backward radiation without decreasing the efficiency. The cavity is designed to ensure an impedance bandwidth exceeding 16:1 ratio (from 350 MHz to 5.5 GHz). Simulated and measured results are presented and compared, demonstrating competitive performance in terms of impedance bandwidth and efficiency. Time–domain measurements indicate fidelity of 0.62 at boresight.