I designed a WVNY RF7 2-element yagi using a moment method computer model. The "gamma match" impedance was measured and tweaked for 75 ohms. The gain is 6 dB and the front/back ratio is 8.5 dB. The antenna performs very well, giving a signal strength of around -85 dBm, measured on a spectrum analyzer (about 70 percent strength on my Channel Master DVR+).

For a long time there was a problem with frequent and total loss of reception. The problem would disappear when the neighbors were away. An on/off experiment confirmed it was their Bazz LED lights, about 50 ft away from the antenna. The lights produced a comb of weak spikes in the VHF spectrum, around the -100 dBm level. They replaced the lights by another brand and now all is well.

There were a few other unidentified sporadic RFI sources, but they have magically disappeared over time. Perhaps they will reappear some day, who knows.

I have also tested the mighty Wade J-105-7 10-element yagi on a 40 ft tower. The signal strength and quality read 100 percent, but even this antenna is not RFI-proof.