Abstract: A microstrip to waveguide transition is achieved by passing a portion of a microstrip circuit through an aperture in a transverse wall of a waveguide. The aperture is dimensioned and positioned so as not to significantly disturb propagation in the waveguide. A tab of the microstrip substrate extends through the aperture and into the waveguide, where a probe disposed on the tab couples to energy in the waveguide. The probe is connected to the microstrip circuit by means of a transition section on the tab within the aperture. The transition section is as narrow as possible to minimize capacitive coupling to the waveguide wall and is an integral multiple of one-half wavelength for a smooth impedance match from the probe to the microstrip.

Abstract: An improved monopulse comparator circuit is achieved by a unique circuit layout. Four hybrid junctions are arranged on a low dielectric constant substrate and are interconnected in such way as to form a closed square figure. Distances between adjacent hybrid junctions are thus minimized. Input lines which connect the comparator circuit to a monopulse antenna array are disposed on the substrate external to the closed figure, as are output lines which connect the comparator to a monopulse guidance system. Right angle microstrip to waveguide transitions are used so that the comparator circuit need not be integrated onto the same substrate as the antenna array and the guidance system. The entire comparator layout is channelized to increase isolation between closely spaced lines.