Impedance matching between ADTR1107 & patch antenna

The ADTR1107 seems to be set to 50 ohms for broadband as far as the S-parameters are concerned, but is it OK to connect a narrowband patch antenna behind it whose input impedance is almost total reflection at frequencies other than the transmit frequency? I am using ADAR1000 and ADTR1107 for the front end of the phased array antenna, and it oscillates when the gain of ADAR1000 is set high. Since the change in oscillation frequency with respect to the phase setting of the ADAR1000 matches the slope of the phase frequency characteristics of the S21 of the ADAR1000, I think the cause of oscillation is the lack of isolation between the ADTR1107 output and the ADAR1000 input, but please advise if there are any precautions regarding impedance matching.