Hybrid diplexer and circulator frontend for GPS receiver and satcom modem sharing common antenna

A hybrid diplexer-circulator system including a circulator and a modified-diplexer is provided. The circulator includes a first circulator-port, a second circulator-port coupled to a first chain comprising a receiver module, and a third circulator-port coupled to a second chain comprising a satellite modem. The first chain receives first-frequency signals and reflects second-frequency signals. The second chain receives the second-frequency signals reflected from the first chain and transmits third-frequency signals. The modified-diplexer includes: a first diplexer-port of the modified-diplexer, which is shared as the first circulator-port; a second diplexer-port; and third diplexer-port in the second chain. The second diplexer port inputs the first-frequency signals from a filter in the first chain. The third diplexer-port: inputs the second-frequency signals reflected by the first chain; outputs the second-frequency signals to be received by the satellite modem; inputs third-frequency signals transmitted by the satellite modem; and outputs the third-frequency signals to the third circulator-port.