Omnidirectional Dual-Polarized Antenna With Sabre-Like Structure

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 waveguidefed 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 × 29 × 9 mm3. (0.42λ0× 0.24λ0× 0.07λ0, λ0is 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.