RT169 raises valid observations - are you sure the problem is static?
The first thing that comes to mind when you say the 2 further away signals are fine but the closer-in signal is not, is that your receiver front-end is been saturated.
Are these analogue or digital transmissions? Are they FM or AM? Do you have an AGC switch on the receiver, and in what way does the demodulated signal sound change when the AGC is on/off. Do you have Wide band and Narrow band - and again, how does the demodulated sound change between WB/NB setting? The background noise - just how does it sound, is it a hum or buzz, is it constant in pitch/tone and if present what do changes in any of the above receiver settings have on any background sound and/or the assocaited pitch & tone?
You could try a piece of wire connected to or inserted into the receiver coax socket - one piece cut to the resonant freq/length and another say, just a few inches long - now what change/s is there in demodulated audio?
...... there are a whole bunch of possibilities here. Some more background detail would be great.