Unitary microwave transmit-receive duplex system with coaxial ring hybrid transformer

Claim 1

Unitary microwave transmitting and receiving apparatus comprising in combination: 1. a transmit-receive antenna, 2. a first and a second signal path each connected to said antenna and including, in the order named, an antenna band-pass filter, a T-junction, microwave switch, and a transmitter, 3. said transmitters having different carrier frequencies and said filters having band-pass characteristics to encompass the signal frequency band of the respective transmitters, 4. a heterodyning oscillator having a frequency substantially midway between said carrier frequencies, lambda , 5. a balanced modulator frequency changer, 6. a hybrid microwave conductor closed upon itself and having a. first, second and third input coupling points equally spaced along said conductor by electrical distances equal to lambda /2 or a whole number multiple thereof. b. means connecting said first input coupling point to said oscillator and for connecting said second and third input coupling points alternatively to one of said filters via the associated microswitches, and c. a pair of output coupling points upon said conductor located on either side of and spaced from said first input coupling point by electrical distances equal to lambda /4 or an odd multiple thereof, each of said output coupling points connected to a different signal input of said balanced modulator frequency changer, and 7. control means in each of said signal paths to disable either of said transmitters during transmission by the other transmitter, and vice versa, 8. whereby to enable a signal transmission on either carrier frequency by one of said transmitters and simultaneous signal reception on the other carrier frequency via said frequency changer, and vice veRsa.