NO problem using third party antennas. There is a white paper posted somewhere on the Line 6 site that shows a bunch of them. Also we had quite good luck with the RF Venue CP24 helical antenna. It has about 9 dB of gain and many times will work better than the P180/360 antennas because their line amps will up the noise floor. So even though you get a little less gain you get a better signal to noise ratio which is more likely to be a gating factor.