How can we use the Site Master to make antenna isolation measurements?
You need a 2-port measurement so you can send out a signal from a transmit antenna and monitor the signal coming in at the receive antenna. You can either use the S251C with its insertion loss mode or you can use the Site Master and Cell Master with its Transmission Measurement modes. The benefit of using the S251C is that the nominal output power is higher or about +6 dBm vs. about -10 dBm with Option 21. The further apart the antennas are, the lower the signal will be in the Rx antenna and for optimum dynamic range it is helpful to use max power level. When you make the measurement, you start out calibrating the instrument with a through cal (Option 21) or a 1-path 2-port cal (S251C insertion loss mode). When you connect a cable from the RF out to the RF in port of the Site Master, you should see a flat signal. When you then connect RF Out to a Tx antenna and RF in to a Rx antenna, you are essentially looking at how much power is going into the Rx antenna or the acutal isolation between the two. Depending on the system and the setup, the values will vary and you'll need to check with the system engineer to see what is recommended for your system.