Omnidirectional Dual-Polarized Antenna With Sabre-Like Structure

Abstract

In this communication, a sabre-like dual-polarized antenna with omnidirectional patterns in the azimuthal plane is presented for low wind drag airborne applications. The proposed antenna consists of a thin cavity for the horizontal polarization and a coplanar waveguide-fed monopole for the vertical polarization. The colocated thin cavity and the monopole construct a compact sabre-like structure with low wind drag, and it is suitable for airborne use. Especially, a hybrid-feeding structure, including a capacitive slot-coupled microstrip line and an inductive probe, is proposed for impedance matching of the thin cavity to provide omnidirectionally horizontal polarization. In order to verify the proposed design, a prototype is fabricated and tested with the dimensions of $42 \times 29 \times 9$ mm3. ( $0.42\lambda _{0} \times 0.24\lambda _{0} \times 0.07\lambda _{0}$ , $\lambda _{0}$ is the free-space wavelength at 2.44 GHz.) The measured −10 dB reflection coefficient bandwidths of the two ports are 2.38–2.51 and 2.28–2.53 GHz. The measured gain variation in the azimuth plane is less than 3.60 and 3.45 dB for horizontal polarization and vertical polarization.