As regards, 1/2 dipoles on 630 meters, they do work. I have one with legs only 30+ degrees apart that seems to perform as well and often better than other stations, if the wsprnet.org map means anything. This antenna is only 10 -16 feet above ground. I am feeding it about 20 watts from an MF Solutions converter -- directly with 50 ohm coax, no tuner needed. That just beats the hell out of building a huge variometer or trying to get a vertical element with a top load into the air and matching it to transmitter output. I do have highly conductive "soil" here. We are located in the Panhandle of Florida and the sadn here is slightly acidic and NEVER dries up below about one foot deep.