Circuit diagram is here . Right angle arrangement antenna and automatic switching unit for GBR-21. Automatic switching circuit diagram is here . But it does not work. So, I removed all electronic parts and added MAR-6 amp.
Circuit diagram is very simple.
You can apply this circuit to your own patch antenna,whip antenna,GP antenna etc. One day, I was testing the current consumption of external antenna. It is very strange but useful. Probably, I cannot understand your English completely. You need superhuman imaginative power, in order to understand my English.