Hi Harry,
do not attempt to connect both, RadarBox and SBS-1, to one antenna simultanously by meens of a simple "T piece". You will suffer a degraded signal by mismatch effects. Proper matching can only be done by means of a "powersplitter", but unfortunatly, that will cause a "3db" (meaning half of the in-put signals "power") loss too, that you idealy have to compensate for by using preamlification ("mastpreamplifierer"), if not taking those attenuated signals into account.
Kind regards,
Karl