Test results from a tower VOR over a forest area

An analysis of the performance of tower VOR in a forest area is made, and the mathematical relations between tower height, counterpoise dimensions and reflecting objects are presented. Various propagation phenomena affecting the performance of such tower VOR antennas and a review of the compromises required to achieve satisfactory radiation of signals to various parts of the vertical pattern characteristic are discussed. Practical results of tests on a tower VOR installation near Frankfurt aerodrome, Germany, are given, along with data on seasonal effects upon course interference.