A reconfigurable quarter-wave patch antenna employing a folded loading stub

Abstract

In this paper, a concept of a compact reconfigurable quarter-wave patch antenna employing a folded loading stub and a tuning varactor is presented. The structure consists of two substrate layers separated by a ground plane. The antenna is placed on the top metal layer whilst the entire feeding structure and the bias circuit are located on the bottom layer. The central result of the paper is the folded stub configuration for this type of reconfigurable antennas, which contributes to antenna miniaturization and also avoids complex bias network on the antenna layer. Simulations predict that, using a single varactor with capacitance range of [0.149, 1.304] pF, the antenna can have a continuous frequency tuning range of about 28% with a radiation efficiency ranging from to 23% to 90%. The antenna size is only 0:13λο x 0:15λο where λο is the free-space wavelength at the minimum frequency of the tuning range.