Analysis and Design of Cavity-Backed Probe-Fed Hybrid Microstrip Antennas on FR4 Substrate

Abstract

A novel cavity-backed probe-fed linearly polarized microstrip antenna based on the concept of hybrid radiators is proposed and implemented. The resulting flush-mounted antenna exhibits symmetrical bandwidth, low cross-polarization radiation in theH-plane, due to its hybrid patch, and low cost, since it can be built on a FR4 laminate. Substrate integrated waveguide technology is used in the fabrication of the metallic cavity. The effect of mutual coupling is analyzed for two classical arrangements: the side-by-side and the collinear configurations.

Analytical Model for Predesigning Probe-Fed Hybrid Microstrip Antennas

“…Here, as in [27], equivalent magnetic sources, positioned along the ungrounded patch walls, lead to the following expression [9,28]:…”

“…Thus, from the perspective of modal interference, any one of the three designed antennas could be used. Nonetheless, a simple way to suppress modes TM x 20 and TM x 21 consists of placing the feeder at y c = b/2, where their electric field is minimal [9,16,28]. In such case, only modes {1, 0} and {1, 2} need to be controlled in the antenna design.…”

“…Although Deschamps [3] proposed the concept of microstrip radiators back in 1953, it was only in the 1970s, with the production of low-loss microwave laminates that this type of antenna started gained popularity [4] and a number of practical applications came about [5]. Nowadays, their peculiar characteristics are established [6][7][8] and they are found as customary components in modern communication systems [9]. Analytical methods, such as the transmission line [10], resonant cavity [11], and electric surface current [12] models, have been extensively used for predesigning planar, cylindrical, and spherical microstrip antennas [6][7][8][13][14][15].…”

“…A convenient way to overcome this limitation consists of using a hybrid microstrip patch, as described in [9,[16][17][18][19][20][21]. In this publication, hybrid microstrip antennas fed by a coaxial probe are predesigned via the cavity model.…”

“…In this publication, hybrid microstrip antennas fed by a coaxial probe are predesigned via the cavity model. Although this model had been previously utilized [9,16,18,22,23], the systematic determination of adequate design criteria has not been fully carried out yet. Such is the primary goal of this work.…”