Study of Masking Effect of Cable and Practical Analysis of FM, VHF and UHF Broadcasting Antenna

摘要

Antenna is a very important part of a communication system. For proper working of a terrestrial communication system antenna parameters such as return loss and standing wave ratio should be checked regularly. In this research paper practical measurement based analysis of FM, VHF and UHF antenna parameters has been carried out. In order to complete this work four numbers All India Radio and Doordarshan terrestrial transmission sites has been selected in Punjab and Himachal Pradesh. Measurement has been taken while repair of the antennas has been carried out at the respective site with Anritsu site master. It is observed that even a very small amount of water drops inside the junction box of an antenna and loose connector can predict different antenna behavior and increases reflection. Cable loss also holds importance while taking measurements. If the masking effect of cable has not been considered then it may have that our measured parameters at the transmitter could predict different antenna behavior than actually at the antenna. So masking effect of cable should be taken care of if cable loss is high.