A Miniaturized Ultra-Wideband Vivaldi Antenna With Low Cross Polarization

Abstract

A miniaturized ultra-wideband Vivaldi antenna is proposed in this paper. Optimized slots are inserted in the radiation patches to obtain a low frequency resonance. Two substrates with radiation patches are put back to back, forming a double-layered structure. Thus, the transverse E-field of the doublelayered structure is significantly reduced due to this symmetric treatment, which gives rise to very low cross polarization. The measured results show that an enhanced impedance bandwidth of approximately 126% in the range of 2.5-11 GHz (S11 <; -10 dB) is achieved. The dimensions of the proposed antenna are 36 mm x 32 mm x 2 mm, and the relative dimensions are 0.3λ0 x 0.26λ0 x 0.02λ0, where λ0 is the freespace wavelength at the lowest operating frequency. Furthermore, the cross polarization is -40 dB over the bandwidth. The time-domain behavior of the Vivaldi antenna is tested, and the results show a low cross polarization in the time domain and admirable time-domain responses.

Keywords

• Ultra-wideband (UWB)
• Vivaldi antenna
• miniaturized
• low cross-polarization