Your antenna may be bad or badly connected (if only getting about 20ft sounds like not really connected) make sure the antenna is well secured. Also any radio transmission is a two sided thing there is the transmitter and the receiver (or if two way/bidirectional there are two transceivers, things that both transmit and receive). That is to say you could have crappy video transmitter (or not well configured, low power output, bad antenna connection, just dead on arrival/doa) or you could have a crappy video receiver. Again maybe on the wrong channel/frequency for the VTX maybe bad antenna connection lots of things can go wrong, if everything goes right you have good video signal in an open field with not much between you and the quad if you sit in a cave or under a thick tree even if your setup is perfect otherwise you are going to have a bad time because the concrete and vegetation contain moisture (and other stuff) that will absorb the signals.