A Compact Wideband Circularly Polarized Microstrip Slot Antenna with Parasitic Elements

A compact wideband circularly polarized (CP) microstrip slot antenna (MSA) with parasitic elements is designed in this letter. The CP MSA comprises a square-loop sequential-phase (SP) feeding configuration, four rotated rectangular patches, and four L-shaped slots embedded in the ground plane. The square-loop SP feeding structure comprises a square loop and an arc-shaped strip, which could provide a 270° phase difference. Four rotated rectangular patches are placed at the edge of the square-loop feeding configuration using a capacitively tightly coupled feeding method to stimulate the CP resonant mode. After selecting these elements and tuning proper dimensions, the broad operating bandwidths of 4.38–5.25 GHz (18%) for |S11| <–10 dB and 4.65–5.31 GHz (13.2%) for AR <3 dB could be realized. Hence, the designed CP MSA has a potential application value in wireless communication.

Evaluation of a Dielectric-Only Transmitarray for Generating Multi-Focusing Near-Field Spots Using a Cluster of Feeds in the Ka-Band

A transmitarray antenna is evaluated to generate a multi-focusing spot area in the Fresnel region of the antenna in the Ka-band. The antenna is designed to focus the radiated field at a certain point using a central feeding configuration. The number of feeds is increased to create as many focusing spots as feeds. The feeds are placed along an arc defined in the principal planes of the transmitarray, radiating independent near-field spots and providing a solution with a wide-angle spot scanning without an antenna displacement and a high isolation between feeds. To validate this concept, a transmitarray based on dielectric-only cells is designed and simulated under full-wave conditions. Then, this design is manufactured using a 3D printing technique, and the prototype is measured in a planar acquisition range. Measurements are performed for different feed positions in order to validate the multi-focusing capability of the antenna. Measurements and simulations show a high agreement and validate the proposed design technique.

Design and Analysis of a Novel Compact Wideband Antenna with Two Excited Modes

A novel planar compact wideband antenna with coplanar waveguide (CPW) feeding configuration is presented in this paper. The proposed antenna is fed and coupled by the CPW feeding line at the same time. Therefore, two distinct excited modes are realized. Besides, detail investigation is presented as well to demonstrate the properties of the proposed antenna. Eventually, the prototype of the proposed antenna with optimal design is fabricated and tested. The proposed antenna, with a fairly compact size of 24 mm × 18 mm × 1 mm, has a measured 10 dB impedance bandwidth spanning from 3.05 GHz to 6 GHz, about 65.2%. Moreover, stable radiation patterns over the operating band are obtained. Furthermore, time-domain characteristics of the proposed antenna are also investigated.