Double balanced microwave mixer using balanced microstrip baluns

Claim 2

A double balanced microwave mixer comprising a diode bridge having four substantially matched diodes; first means for directly supplying an RF signal input; second means for directly supplying a local oscillator input third means for directly taking an output, and first and second balanced microstrip baluns whose substrate has a higher dielectric constant than the dielectric constant surrounding the baluns and whose metallic strip on one side plane of each of said baluns is tapered as a function of distance from said first and second means to said diode bridge, said baluns placed respectively between said first and second means and said bridge.

Claim 3

A mixer as in claim 1 further including a frame, the dielectric substrate supported by said frame, said diode bridge placed within said substrate and said balanced microstrip baluns formed by placing metallic strips of the desired impedance on either side of said dielectric substrate.

Claim 4

A mixer as in claim 1 wherein said first, second and third means includes connecting means to unbalanced transmission lines.

Claim 5

A device as in claim 3 wherein the tapering of the metallic strips is such that the impedance transformation from the unbalanced lines to the balanced bridge follows a Chebyshev distribution so as to produce a minimum mismatch in the transition from the unbalanced to the balanced conditions.

Claim 6

A device as in claim 2 wherein said substrate is suspended within air and is in direct contact with said frame only at the points of support, and wherein said substrate consists of an alumina dielectric.

Claim 7

A device as in claim 2 and further comprising inductance coils placed between said third means and said bridge and decoupling means associated with said first and second means for providing a high impedance at the output frequency.

Claim 8

A device as in claim 5 further including RF lossy material placed around the edge of said substrate between said substrate and said frame.

Claim 9

A device as in claim 1 wherein said diodes are beamlead Shottkey diodes.

Claim 10

A double balanced microwave mixer having substantial frequency independent balun for the transmission of microwave electrical energy formed of a balanced microstrip comprising a Dielectric material, a first metallic strip placed on one side thereof and whose width provides the desired characteristic impedance, and a second metallic strip placed on the other side of said dielectric material, wherein said second metallic strip is tapered as a function of distance from the start of the balun until it equals the width of said first metallic strip.

Claim 11

A double balanced microwave mixer having substantial frequency independent balun for the transmission of microwave electrical energy formed of a balanced microstrip comprising a Dielectric material, a first metallic strip placed on one side thereof and whose width provides the desired characteristic impedance, and a second metallic strip placed on the other side of said dielectric material, wherein said second metallic strip is tapered as a function of distance from the start of the balun until it equals the width of said first metallic strip.

Claim 12

A device as in claim 8 wherein one end of said balun is connected to an unbalanced transmission line; the other end is connected to a balanced line and said tapering is such that the impedance transformation from said unbalanced to said balanced lines follows a predetermined distribution so as to produce minimum mismatch in the transition from the unbalanced to the balanced conditions.

Claim 13

A device as in claim 10 wherein said balanced lines contain a double balanced diode bridge arrangement, supplied with a signal input, a local oscillator input and producing an output, and wherein a balun is placed between each of said inputs and said bridge.

Claim 14

A double balanced microwave device comprising four substantially matched diodes forming a bridge arrangement of four arms and first and second pairs of diagonally opposing terminals therebetween; a first means directly supplying a first input signal; a second means directly supplying a second input signal; a third means for directly taking an output signal; a dielectric substrate whose dielectric constant is higher than the surrounding dielectric constant, said diode bridge placed within said substrate wherein said terminals are externally available for contact therewith; a first balanced microstrip balun connected between said first means and a first pair of diagonally opposing terminals; a second balanced microstrip balun connected between said second means and a second pair of diagonally opposing terminals; said first and second balanced microstrip baluns having one of their sides tapered, and inductance coils connected between said third means and either of said diagonally opposing terminals.

Claim 15

A double balanced microwave device comprising four substantially matched diodes forming a bridge arrangement of four arms and first and second pairs of diagonally opposing terminals therebetween; a first means directly supplying a first input signal; a second means directly supplying a second input signal; a third means for directly taking an output signal; a dielectric substrate whose dielectric constant is higher than the surrounding dielectric constant, said diode bridge placed within said substrate wherein said terminals are externally available for contact therewith; a first balanced microstrip balun connected between said first means and a first pair of diagonally opposing terminals; a second balanced microstrip balun connected between said second means and a second pair of diagonally opposing terminals; said first and second balanced microstrip baluns having one of their sides tapered, and inductance coils connected between said third means and either of said diagonally opposing terminals.

Claim 16

A device as in claim 12 for use as a mixer wherein said first input signal is an RF signal, said second input signal is a local oscillator signal and said output signal is the IF signal produced by the mixer.

Claim 17

A device as in claim 12 further comprising a frame, and wherein said first, second and third means include coaxial cable connectors placed on said frame, and said dielectric substrate is supported within said frame and substantially surrounded by air.

Claim 18

A device as in claim 12 for use as a microwave mixer wherein when the third signal is of a frequency lower than that of the first input signal the frequency of the second signal is the difference between the first signal and that of the third signal.

Claim 19

In a double balanced microwave mixer supplied with an input signal, a local oscillator signal and producing an output signal comprising four substantially matched diodes and balanced microstrip baluns connected between said inputs and said diodes, the diode assembly consisting of a dielectric substrate, four separate metallized areas placed on one surface thereof, first two conducting leads, each connected to one of two of said metallized areas and extending transverse to said surface, a hole placed in each of the remaining two metallized areas and extending through the dielectric thereunder, second two conducting leads, each connected to a one of said remaining two metallized areas, passing through said holes and extending transverse to said surface opposite to said first two leads, said four diodes connected to said metallized areas in an electrical bridge arrangement, and said microstrip baluns connected to said leads.

Claim 20

In a double balanced microwave mixer supplied with an input signal, a local oscillator signal and producing an output signal comprising four substantially matched diodes and balanced microstrip baluns connected between said inputs and said diodes, the diode assembly consisting of a dielectric substrate, four separate metallized areas placed on one surface thereof, first two conducting leads, each connected to one of two of said metallized areas and extending transverse to said surface, a hole placed in each of the remaining two metallized areas and extending through the dielectric thereunder, second two conducting leads, each connected to a one of said remaining two metallized areas, passing through said holes and extending transverse to said surface opposite to said first two leads, said four diodes connected to said metallized areas in an electrical bridge arrangement, and said microstrip baluns connected to said leads.

Claim 21

A device as in claim 16 wherein said diodes are placed upon said substrate, and said diodes and substrate are covered with an epoxy coating.

Claim 22

In a double balanced microwave mixer supplied with an input signal, a local oscillator signal and producing an output signal, comprising four substantiallY matched diodes and balanced microstrip baluns connected between said inputs and said diodes, the diode assembly consisting of: a dielectric substrate, a metallized area placed on both upper and lower surfaces thereof, a first hole extending through said metallized areas and dielectric, two equal smaller holes placed through said metallized areas and dielectric, said smaller holes being symmetrically placed on either side of said first hole and partially intersecting it, said holes in combination producing a discontinuity in both metallized areas, thereby forming a first and second part thereof, a first diode placed in said small hole having one end thereof connected to a first part of the upper surface of said metallized area and a second end thereof connected to a second part of the lower surface of said metallized area, a second diode placed in said first hole having one end thereof connected to the a first part of the upper surface of said metallized area and a second end thereof connected to a second part of the upper surface of said metallized area, a third diode placed in the other of said small holes and having one end thereof connected to a first part of the lower surface of said metallized area and a second end thereof connected to a second part of the upper surface of said metallized area, a fourth diode placed in said first hole and having a first end thereof connected to a first part of the lower surface of said metallized area and a second end thereof connected to a second part of the lower surface of the metallized area, whereby the lengths of all said connections will be substantially identical, and said microstrip baluns are connected to the metallized areas.

Claim 23

In a double balanced microwave mixer supplied with an input signal, a local oscillator signal and producing an output signal, comprising four substantiallY matched diodes and balanced microstrip baluns connected between said inputs and said diodes, the diode assembly consisting of: a dielectric substrate, a metallized area placed on both upper and lower surfaces thereof, a first hole extending through said metallized areas and dielectric, two equal smaller holes placed through said metallized areas and dielectric, said smaller holes being symmetrically placed on either side of said first hole and partially intersecting it, said holes in combination producing a discontinuity in both metallized areas, thereby forming a first and second part thereof, a first diode placed in said small hole having one end thereof connected to a first part of the upper surface of said metallized area and a second end thereof connected to a second part of the lower surface of said metallized area, a second diode placed in said first hole having one end thereof connected to the a first part of the upper surface of said metallized area and a second end thereof connected to a second part of the upper surface of said metallized area, a third diode placed in the other of said small holes and having one end thereof connected to a first part of the lower surface of said metallized area and a second end thereof connected to a second part of the upper surface of said metallized area, a fourth diode placed in said first hole and having a first end thereof connected to a first part of the lower surface of said metallized area and a second end thereof connected to a second part of the lower surface of the metallized area, whereby the lengths of all said connections will be substantially identical, and said microstrip baluns are connected to the metallized areas.

Claim 24

The apparatus of claim 18 wherein said portions of said frame contacting said substrate also contact the metallic strip on the face of the substrate contacted by the frame.