Radiation Phase Control of a Single-Layer Ring Microstrip Antenna Fed by an L-Probe with a Variable Reactance Circuit

This paper presents a single-layer ring microstrip antenna (MSA) fed by an L-probe with a variable reactance circuit for a beam adjustable microstrip antenna arrays (BA-MSAA). The BA-MSAA consists of a central patch element fed by a feeding line and two parasitic patches with a variable reactance circuit (VRC) adjacent to the center patch. Radiation patterns of the BA-MSAA are controlled electronically by reactance values of the VRCs. In order to enhance the beam-shaping performance of the BA-MSAA, it is necessary to feed the all patches and to control the radiation phases of the fed patches independently. For this purpose, a single-layer ring MSA fed by an L-probe with a VRC is presented in this paper. The prototype MSA with the VRC is designed at 5 GHz. The radiation phase of the prototype MSA can be controlled in the range of about 80 degrees when the normalized reactance of the VRC is varied from -2.0 to 2.0.