Design of a printed non‐planar dual‐polarised log‐periodic dipole array

Abstract

An efficient and low cost approach to realise a non-planar dual-polarised log-periodic dipole array antenna (LPDA) using printed circuit board technology is proposed which achieves a high bandwidth and operational frequency. The proposed antenna utilises a very short transition from a coaxial cable to a balanced four-conductor transmission line to realise an ultrawide bandwidth balun and input impedance matching. An analysis of the utilised four-conductor transmission line alongside its comparison to two-conductor transmission line of a planar LPDA is also presented. Two prototypes of the antenna operating over the frequency ranges of 1-13 GHz and 1-18 GHz were designed, fabricated, and tested. An average gain of 6.7 dBi is obtained. Measured voltage standing wave ratio, cross-polarisation and front-to-back ratio of both prototypes are better than 2.6, −14, and 22 dB respectively.