Effect of ice-covered element on the performance of a UHF Yagi antenna

The paper describes an experimental study on the effect of ice-covered elements on the pattern and impedance characteristics of a 5-element Yagi with 9.5-mm diameter elements designed to operate at 300 MHz. Some guidelines are suggested for the design of a Yagi antenna operating under icing conditions: (1) to compensate for the loading effect of ice on the electrical length of an element, the Yagi should be designed for a frequency about 5% higher than the desired operating frequency; (2) by staggering the detuning effects of ice and thereby reducing the overall detuning effect, the Yagi should be designed with directors of unequal length; and (3) the Yagi should be designed with elements of large diameter due to the fact that for a dielectric-coated wire antenna the change in resonant length is directly proportional to the dielectric thickness/wire radius ratio.