High power tunable band pass filter design using PIN diode in VHF band against antenna coupling problems on aircrafts

In this thesis, a tunable band-pass filter was designed in 118-136 MHz VHF band to eliminate coupling problem between the antennas while performing the relay function of the radios used in Unmanned Aerial Vehicles or similar platforms. High power handling components were selected in filter design to use filter both receiver and transmitter lines. Therefore, PIN diode was used in the filter design as a tunable element to provide capacitive variability. After the design and simulation developments were completed, PCB of the filter was produced. S-Parameter measurements of the board and its tuning performance in the band were examined by using the Network Analyzer device. In addition, RF power was applied to filter input gradually by using RF Signal Generator, power amplifier and attenuator in order to determine the power handling characteristic of the filter. Finally, the filter was connected to the radio and the relay function was performed.