US Patent 11356134 Integrated TCAS/transponder transmitter architecture

A transmitter for an aircraft is disclosed. The transmitter comprises a first channel configured to transmit first radio frequency (RF) signals in a first direction and a second channel configured to transmit second RF signals in a second direction. A branchline coupler is communicatively coupled to the first channel and the second channel. The branchline coupler comprises one or more quarter wave transformers and a set of PIN diode switches configured to have a high impedance responsive to the transmitter being in an amplitude-based mode and a low impedance responsive to the transmitter being in a phase-based mode.