Four-square phased array for multi-beam applications using novel matrix feed

Abstract

Modern communications systems use multi-beam antennas for the sectorization of 360° azimuthal coverage or diversity and MIMO concepts. One suitable antenna realization is based on the phased array principle, where four elements placed at the edges of a square are required in order to form four overlapping beams in azimuth. In its basic form, excitation phases of 0°, 90° and 180° are required for beam forming. The paper presents a novel multi-beam matrix network created by four 90°-hybrid couplers which realizes the required excitation for four beams spaced by 90° in the azimuth plane. A proof-ofconcept antenna was designed which employs miniature surfacemount couplers in a microstrip feed network and uses vertical monopole radiators.

Study of Monopole Radiators for Planar Circuit Integration

“…In a recent investigation of an electrically small -four element phased array antenna for 360°-multi-beam communications applications [1] it was found that the primary requirements for the radiator elements was omnidirectional pattern in the azimuth plane and small size in the array plane. In a similar design exercise [2], patch antennas were used as radiators: However, due to the half-wavelength dimension of patch antennas the array spacing is heavily limited and demands high permittivity dielectric substrate to be used for the intended small size array.…”

A programmable compact wide-band RF feed network

“…The beam ports are usually isolated and the number of beams are typically a power of two. A four-beam Butler matrix feeding a four-square monopole array was presented in [2] and covered a range of frequencies from 2.4 to 3.4 GHz. Another matrix fabricated using MMIC technology was developed in [3].…”

Detecting the evil twin attack in a single hop wireless network using four-square antennas

“…The phase comparison monopulse technique measures the phase difference of a signal from two or more antennas to estimate the direction of arrival. The antennas are usually separated a half-wavelength apart to reduce the electromagnetic interference, which is detrimental to an antenna's performance [17]. In this technique, the received signal at each antenna is of equal amplitude but different in phase.…”