Microwave frequency converter

Claim 2

A frequency converter comprising: (a) a subharmonic mixer having one RF, one IF and two LO ports, said mixer including two pair of antiparallel diodes with each diode pair being connected to one respective LO port, (b) a band-pass filter having an input port and a pair of output ports, said output ports being connected to the LO ports of said subharmonic mixer, and (c) a local oscillator signal source having an output port at which a number of signals at different frequencies are produced simultaneously, said source output port being connected to the input port of said filter to supply said mixer through said filter with an LO signal at a single frequency selected from said number of signals from said source.

Claim 3

A frequency converter, as claimed in claim 1, wherein said local oscillator signal source is a comb generator.

Claim 4

A frequency converter as claimed in claim 1, wherein said filter is a tunable YIG filter.

Claim 5

A frequency converter as claimed in claim 3, wherein said mixer is single balanced, and said YIG filter comprises two separate, but substantially similar sections, each section having an input and output port and each being connected at their respective output ports to a different set of said diode pairs, while both sections are connected together at their input ports to form a single input port for said band-pass filter.

Claim 6

A frequency converter as claimed in claim 4, wherein said converter is fabricated by means of microwave integrated circuit techniques, said mixer RF port is connected to an RF divider to supply said diode pairs with the RF signal within said mixer, said RF divider comprising two transmission lines which are short with respect to a wavelength at the RF operating frequency and are joined together to form the RF input port of said mixer, said LO ports are connected to said YIG filter sections via LO transmission lines which are short with respect to a wavelength at the LO operating frequency, said YIG filter sections consist of YIG spheres and two orthogonal untapped coupling loops, with the local oscillator signal source being connected to opposite ends of the input coupling loops of each filter section respectively to provide out-of-phase local oscillator signals to the diode pairs, and both of said filter sections are located within a single magnetic field to provide frequency tracking of the filter sections.