Effect of the dish angle on the wet antenna attenuation

Abstract

Rain attenuation is a major factor to demean the system performance at frequencies above 10 GHz. This paper deals with wet antenna attenuation at Ku band with different elevation angles and rain rate. throughout the Ku-band propagation experiment, it was discovered that the rain water on the antenna caused significant attenuation. It is necessary to estimate the losses caused by water on the antenna in order to separate these losses from the atmospheric propagation losses. The experiment was done at USM Engineering Campus to study the attenuation for the physical parameters. At Ku band the RF signal was generated by a signal generator and transmitted via horn antenna. The signal was received using a smooth offset antenna of 61 cm by 54 cm (Astro dish) and measured using a spectrum analyzer. To simulate the rain rate, PVC pipes with equally distant bores were implemented. Three cases were considered: First, one pipe was used to simulate low rain rate; second, two pipes were used to simulate medium rain rate; third, three pipes were used to simulate heavy rain rate. In addition, the tap was used to control the flow of water to get more values of rain rate. The total attenuation of RF signals due to water layer on the feed and on the reflector feed was found to be 3.1 dB, at worst case. On the other hand, the attenuation of the RF signal due only to feed was 2.81 dB, so major attenuation occurred was from feed.