Mixer for use in a microwave system

A mixer comprising:

• A. a pair of mixer diodes,
• B. a member housing said mixer diodes, and providing a rectangular waveguide chamber suitable for propagating a wave in a TE 10 mode and having axis extending in the Z dimensions, the E field of said TE 10 mode having a Y axis orientation, parallel to the shorter waveguide dimensions, the X axis being parallel to the longer waveguide dimension and transverse to the Y and Z axis, said waveguide having
• (1) a first opening at one end for coupling to a waveguide supplying signal waves to said mixer,
• (2) a second opening at the other end for coupling to a waveguide supplying local oscillator waves to said mixer, and
• (3) a third opening in a lateral wall for said member, for coupling the mixer output to an intermediate frequency amplifier;
• C. a dielectric substrate, providing a site for said mixer diodes, said substrate lying substantially in the Y Z plane of said waveguide and having a first patterned metallization on one surface thereof and a second patterned metallization on the opposite surface thereof, said metallization successively providing first, second, third, fourth, and fifth consecutive region in which:
• (1) said first metalllization in said first region between said first opening and said diode site provides a planar tapered slot for coupling to said E field and is dimensioned to match the characteristic impedance of the waveguide to the impedance at the mixer diode site;
• (2) said first and second metallizations in said fifth region between said second opening and said fourth region provide a non-coplanar tapered slot for coupling to said E field and rotating the Y axis oriented E field to an X axis orientation, said pattered metallizations being tapered to match the characteristic impedance of the waveguide to an impedance value comparable to the impedance at the mixer diode site;
• (3) said first and second metallizations in said fourth region form, respectively, the top and ground plane conductors of a microstrip line with an X axis oriented E field and further provide:
• (i) a hgih pass filter for passing local oscillator waves toward said mixer diode site but blocking intermediate frequency waves from said second opening, and
• (ii) a tap disposed between said mixer diode site and said high pass filter, for deriving waves at the intermediate frequency,
• (4) said first metallization in said third region consists of at least two conductor portions spaced from said top conductor of said microstrip line to form two coplanar slots with said top conductor at the center, said ground plane conductor continues from said fourth region, through said third region and terminates at the boundary between said third region and second region, for rotating the X axis oriented E field from said microstrip line in clockwise and counter clockwise directions to form two substantially equal Y axis oriented E field components, both or like sense in relation to said top conductor of said microstrip line,
• (5) the first metallization in said second region forms a "T" junction slot coupled to the planar tapered slot of the first region that branches into two coplanar slots with said top conductor of said microstrip line at the center, said two coplanar slots continuing into an orientation parallel to said Z axis, each of said mixer diodes being sited across one branch of said "T" junction and poled for alternate conduction in successive half cycles of the local oscillator waves and poled for simultaneous conduction in alternating half cycles of the signal waves, and
• said two coplanar slots conduct intermediate frequency waves arising in said mixer diodes via said microstrip line to said tap for coupling to said third opening.