Radio frequency (RF) feedthrough system and method

An aviation transponder system comprising:

• a permanently-mounted antenna;
• a circulator connected to said antenna;
• a signal splitter connected to said circulator;
• a receiver connected to said signal splitter;
• said circulator selectively directing received signals whereby the receiver is selectively isolated from high-power transmitted signals;
• an external connector connecting the signal splitter with the receiver;
• the permanently-mounted antenna being used by the receiver and received RF signals being fed through the external connector to the receiver;
• said receiver being GNSS-equipped;
• said circulator having operating modes configured for:
• a) sending signals from the transmitter to the permanently-mounted antenna in a first mode of operation;
• and b) taking signals received on the external antenna and routing them to the receiver in a second mode of operation;
• a plurality of PIN limiter diodes directly connected to the circulator and adapted for limiting current passing from said permanently-mounted antenna to said receiver in said second mode of operation;
• said permanently-mounted antenna, said permanently-mounted receiver and the circulator comprising an aviation transponder system;
• and
• said transponder system being configured for adding an external portable device that can receive input information from an existing antenna and send output information to a display unit.

A method of passing RF signals through a transponder, which includes the steps of:

• providing said transponder with a permanently-mounted antenna;
• providing a circulator connected to said antenna;
• providing a signal splitter connected to said circulator;
• providing a receiver connected to said signal splitter;
• providing an external connector connected to said signal splitter;
• providing a receiver connected to said signal splitter through said external connector, said receiver being adapted for receiving RF signals from said signal splitter through said external connector;
• providing a plurality of PIN limiter diodes directly connected to the circulator and adapted for limiting current passing from said permanently-mounted antenna to said receiver in said second mode of operation;
• providing said permanently-mounted antenna, said permanently-mounted receiver and the circulator comprising an aviation transponder system;
• and
• providing said transponder system being configured for adding an external portable device that can receive input information from an existing antenna and send output information to a display unit.