A Dual Circularly Polarized Omnidirectional Antenna for Radar-Warning Receiver

This paper proposes a design of a dual circularly polarized antenna for radar-warning receivers. The antenna has an omnidirectional radiation pattern to emphasize a 360° coverage to detect threatening radar signals from all possible directions. The antenna works across the L-band and covers the frequency band from 1.2 to 1.4 GHz with $\text{VSWR} \leq 1.5$ for industrial standard. The proposed antenna consists of two sections, radiators and a feeding network. The radiators are two crossed orthogonal dipoles printed on opposite sides of an FR-4 laminate while the feeding network is an equal quad phase-shift T-junction. The radiators and the feeding network are linked by two coaxial cables. The antenna has a sable gain of 2.25 dBic and an axial ratio bandwidth of 0.2 GHz. Also, being of small size, low profile and lightweight makes the proposed design an excellent candidate for radar-warning receiver systems.