Band Pass Filter manufactured by Microwave Filter Company. This is model 7893D C-Band Filter.
In areas of dense RF transmission a satellite antenna can pick up unwanted frequencies that can cause interruption and confusion to the receiving demodulator. To combat this problem a bandpass filter placed on the receiving port of a satellite antenna to remove extraneous signals.
Only signals within the range of 3.7GHz to 4,2GHz are allowed to pass through.