Radiation Pattern-Agile Dual Planar Inverted-F Antenna

Abstract

A radiation pattern-agile antenna capable of generating omnidirectional, unidirectional, and bidirectional patterns is presented. The proposed design demonstrates a new technique for achieving pattern configurability with downtilt by using dual planar inverted-F antennas (PIFAs) in a back-to-back configuration with a single folded ground plane and bandwidth enhancement via parasitic elements. The radiation pattern can be controlled by exciting the PIFA ports with one of several potential feeding methods. The antenna's measured impedance bandwidth is from 1650 to 2200 MHz ( $|{S}_{11}|$ $ $-$ 10 dB), and it was designed for peak gain at a 15 $^\circ$ downtilt angle. In the omnidirectional mode, the antenna achieves a gain of more than 5 dBi with a variation from ideal omnidirectionality of less than 3 dB across its operational band. The unidirectional mode achieves a measured realized gain of up to 8 dBi with a front-to-back ratio of at least 15 dB, and the bidirectional mode achieves gains of up to 5 dBi with a front/back-to-side ratio of at least 10 dB.