Radio frequency (RF) feedthrough system and method

1. 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;

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 module 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.

2. The aviation transponder system of claim 1 , which includes:

an external connector connecting the signal splitter with the receiver; and

wherein the permanently-mounted antenna is used by the receiver and received RF signals are fed through the external connector to the receiver.

3. The aviation transponder system of claim 1 , wherein the receiver is permanently-mounted.

4. The aviation transponder system of claim 1 , wherein the receiver is portable.

5. The aviation transponder system of claim 1 wherein the receiver is a communications (COM) receiver.

6. The aviation transponder system of claim 1 , which includes:

the receiver comprising a permanently-mounted navigation (NAV) receiver; and

a portable receiver comprising a portable navigation (NAV) receiver.

7. The aviation transponder system of claim 6 , wherein the permanently-mounted receiver is an ADS-B receiver and the portable receiver is a portable ADS-B receiver.

8. The aviation transponder system of claim 6 , wherein the receivers are equipped with Global Navigation Satellite Systems (GNSSs).

9. The aviation transponder system of claim 1 , which includes:

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.

10. 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.

11. The aviation transponder system of claim 10 , wherein the receiver is permanently-mounted.

12. The aviation transponder system of claim 10 , wherein the receiver is portable.

13. The aviation transponder system of claim 10 , wherein the receiver is a communications (COM) receiver.

14. The aviation transponder system of claim 10 , which includes:

the receiver comprising a permanently-mounted navigation (NAV) receiver; and

a portable receiver comprising a portable navigation (NAV) receiver.

15. The aviation transponder system of claim 14 , wherein the receivers are ADS-B receivers.

16. 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.

17. The method according to claim 16 , which includes the additional steps of:

providing a GNSS component in said transponder; and

deriving GNSS-based positions with said GNSS component.