Sidelobe level reduction using Teflon for a microwave and millimetre-wave antipodal Vivaldi antenna.

A new technique for lowering the sidelobe level (SLL) of the microwave and millimetre-wave antipodal Vivaldi antenna (AVA) has been presented in this study. The technique is based on introducing tapered-shape Teflon surrounding AVA to couple energy propagated from the antenna and produce stronger radiation in the end-fire direction and as a result, it offers wideband low SLL. Some features of the presented antenna with the utilised new technique are summarised as follows: high gain in wide bandwidth corrected tilt of beam on E-plane in wide bandwidth and low cross-polarisation level. The presented antenna is fabricated and the magnitude of the reflection coefficient of the fabricated antenna is tested, which is from 3.2-40 GHz with S11 < -10 dB. It exhibits an average of SLL < -10 dB in E-plane and SLL < -18 dB in H-plane at a wideband of 3.2-40 GHz. Moreover, the lowest E-plane's SLL of -20 dB is achieved over the frequency band of 7-7.5 GHz. The proposed antenna has a small size of 43 (width) × 108 (length) mm2. The proposed antenna with the mentioned features becomes an attractive candidate for imaging applications. [ABSTRACT FROM AUTHOR]