Approach to a suitable directional antenna for UHF radio positioning applications

The phase centre properties of log-periodic dipole (LPD) arrays are examined for suitability in UHF radio positioning systems and are compared with phase properties of commonly used Yagi arrays. LPD arrays offer gain nearly comparable to that obtained from short Yagis, exhibit nearly 180° main lobe coverage with no front quadrant nulls, and show very small phase centre movement over the entire front hemisphere.