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

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 ultra-wide 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.