Linearly Polarized Transmit-array Operating in mmWave Bands, Design, Optimization and Demonstration

Abstract

This paper presents the design and optimization of a transmit-array (TA) operating at 10 GHz. This TA is based on a new unit-cell that allows to generate an easy phase rotation required for TA design, while keeping insertion losses to a minimum. The proposed unit-cell is a simple three metallic layer structure, in which two identical square patches are intercon-nected through an inner via. The optimized structure has a low profile with a total thickness of only 3.2 mm (0.lλ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> ), the simple design allows standard and low cost PCB printing. The unit-cell is designed with CST Microwave Studio and measured with a waveguide measurement system for S-parameters validation. The results show a working bandwidth of 900 MHz (9% relative bandwidth) and insertion losses of 0.3 dB at 10 GHz, full wave simulations show an unit-cell gain of 4.8 dBi making it a very suitable choice for TA design. To demonstrate its performance, a 1-bit transmit-array with 20 × 20 cells is proposed, simulated and manufactured showing a high gain of 21.01 dBi and low side lobe levels (-20.93 dB). Finally, to reduce the overall profile of the TA, a multiple feed TA is conceived using an particle swarm optimization (PSO) algorithm to define the phase compensation distribution and allows a reduction of 50% of the focal length.