Multichannel transmitter combiners employing cavities having low output impedance

Claim 1

A combiner having a lower operating frequency limit and an upper operating frequency limit, said upper and lower limits defining a combiner operating range of frequencies, the combiner constructed and arranged to couple a plurality of transmitters, each operating at a different but closely adjacent frequency, to a single antenna, the combiner comprising: a plurality of filter means, each having an input port for receiving radio frequency energy from one of a plurality of transmitters, and a resonant frequency corresponding to frequency of operation of one of said plurality of transmitters; each of said filter means having an output port; each of said filter means constructed and adjusted to have an output impedance such that: at an operating frequency corresponding to either the lower operating frequency limit or the upper operating frequency limit: (i) the output admittance of said filter means when tuned to resonate at the operating frequency has a first real part and a first imaginary part; (ii) the output admittance of said filter means when resonating at the operating frequency is transformed through transmission lines, that are not an integral multiple of one-half wavelength at resonance, to have a second real part and a second imaginary part; (iii) the combined output admittances, at the operating frequency, of the remainder of said filter means have a third real part and a third imaginary part; and (iv) the second imaginary part is equal to the third imaginary part, but is opposite in sign; impedance transformer means electrically connected to the output ports of each of said filter means, and said impedance transformer means having a single output port; a radio-frequency energy output means for providing said energy to a single antenna; and said output port of said impedance transformer means being electrically coupled to said radio frequency energy output means.