Abstract: An MMIC (Microwave Monolithic Integrated Circuit)-mounted substrate includes a double-metal-foil dielectric substrate having a dielectric substrate with a metal foil pattern formed on both sides of the substrate, an MMIC that is a surface-mount high power amplifier mounted on one side of the double-metal-foil dielectric substrate, and a metal chassis attached to the other side of the double-metal-foil dielectric substrate. The double-metal-foil dielectric substrate has a plurality of through holes. A copper foil pattern that is a metal foil pattern continuously extends to cover the inner surfaces of the through holes and both sides of the dielectric substrate, and solder is buried in the through holes.

Abstract: A polarizer for a dual frequency band is formed of square waveguides of a dual structure. A section is formed which extends in a step-like manner as deeper inside between outer and inner square waveguides. The section is connected to the inner square waveguide at an output portion. A third section protrudes from the sidewall of the inner square waveguide, which section extends in a step-like manner as deeper inside and connected to the other sidewall of the square waveguide at the output portion to provide two divided rectangular waveguides.

Abstract: A circular polarizer includes a low frequency band waveguide (fL), a high frequency band waveguide (fH) formed at the inner side of the low frequency band waveguide (fL) in a coaxial structure, and a dielectric member provided to abut against the inner side of the low frequency band waveguide (fL) and the outer side of the high frequency band waveguide (fH), and inclined by 45° with respect to a linear plane of polarization. Since the dielectric member is provided at an angle of 45° with respect to the linear plane of polarization, the delay of the phase of the electric field passing through the dielectric member becomes greater than the phase of the electric field orthogonal to the dielectric member, whereby a circularly polarized wave can be converted into a linearly polarized wave. Since the dielectric member can be formed by a mold, a circular polarizer that is economic and fit for mass production can be provided.

Abstract: A polarizer for a dual frequency band is formed of square waveguides of a dual structure. A section is formed which extends in a step-like manner as deeper inside between outer and inner square waveguides. The section is connected to the inner square waveguide at an output portion. A third section protrudes from the sidewall of the inner square waveguide, which section extends in a step-like manner as deeper inside and connected to the other sidewall of the square waveguide at the output portion to provide two divided rectangular waveguides.

Abstract: Provided coaxially inside a first waveguide is a second waveguide, so as to form a coaxial waveguide. The first waveguide for the passage of a low-frequency band signal (f.sub.L signal) functions as the outer conductor of the coaxial waveguide while the second waveguide for the passage of a high-frequency band signal (f.sub.H signal) serves as the center conductor of the coaxial waveguide. Feeders for f.sub.L are provided so that they penetrate through the wall of the first waveguide. Feeders for f.sub.H are provided so that they penetrate through both the first and the second waveguide walls. The distance between the first f.sub.L feeder and the first f.sub.H feeder and the distance between the second f.sub.L feeder and the second f.sub.H feeder are set at approximately one quarter of the wavelength of the f.sub.L signal. The distance between the first f.sub.H feeder and a reflector surface is also set at about one quarter of the wavelength.