The GAP Mono seems to perform fairly well. It has a low, flat SWR on 20 and low SWR on 10 also. I have been working DX with it on FT8, CW and even SSB in recent contests. With a tuner I also use it on 17 Meters with good results. It's not a Yagi but for a 16 ft. vertical with 3 counterpoise wires it seems to perform OK.