Dual-band Patch Antenna Matching Network comprised of Separated Ground Layers and Via Posts for Adjustable Return Current Path

Abstract

This paper proposes a dual-band antenna impedance matching network concept that features identical radiation characteristics. The concept is exemplified for millimeter-wave mobile devices but can be scaled to lower and higher frequency spectrum. The method is deduced through an introduction of an additional matching network consisting of inductive distributed elements to formulate adjustable return current paths. This is realized using fragmented ground plane and a series of vias. No modification of the antenna radiating element is required. This new class of matching network enables independent adjustment of the resonance frequencies while maintaining nearly-identical radiation patterns at both frequencies. For experimental verifications, the proposed antenna impedance matching network is fabricated using a low-temperature co-fired ceramic process. The measurement of this single element exhibits dual-band operations at 28.0 GHz and 39.0 GHz, obtaining the realized gain of 5.15 dBi and 5.42 dBi, respectively. In addition, a 1×4 phased array antenna is devised and studied to validate beamforming performances at both frequencies. With the integration of the beamforming circuit, a reconfigurable beamforming is demonstrated at 28.0 GHz, in which the peak measured gain is 10.83 dBi. At the second resonance frequency (39.0 GHz), a passive feeding network is employed to evaluation its beam scanning abilities, and the main beam peak realized gain of 10.40 dBi is ascertained. The result can be extended to any other frequencies while maintaining near-identical far-field characteristics.