The thing I have had the best success with it a product called Spyder. It has 6 to 8 stainless steel wires that flutter in the wind and it works quite well.
One way to tell is a VHF VSWR meter. Maybe you can borrow one.
Since the frequencies are very different, an old CB VSWR meter will not work.Breaker breaker. I used one of those back in the days of CB radios in the '70s. I'll ask around. Thanks.