Compact Patch Antenna Array With Fan-Beam Characteristics for Radar Application

In this paper, a compact
$1\times 4$
patch array antenna with a fan-beam radiation pattern is introduced for use in 3.5 GHz band applications. The proposed antenna consists of a planar two-layer printed structure so that the radiation elements and feeding network are located in the upper and lower layers respectively. In this way, the antenna has very compact dimensions while achieving a high radiation gain. Using a reflector plane under the antenna has improved the radiation pattern and decreased the antenna back radiation. The fabricated array antenna has an impedance bandwidth of 3.35-3.75 GHz (11.27%), a maximum realized gain of 10.91 dBi, and half power beamwidths (HPBWs) of 23.86° and 85.44° on the H- and E-panels, respectively. The overall dimensions of the antenna are
$209\times 32.3\times 3.708$
mm
³
with a
$250\times 50$
mm
²
conductive reflector at a distance of
$\lambda $
/4 from the antenna, and the theoretical and practical results show a good agreement with each other. The presented antenna is suitable for 5G systems and radar applications in the 3.5 GHz frequency band.