Abstract: A high frequency oscillator has a substrate, a resonator circuit which is disposed on one principal surface of the substrate and consists of a closed loop-shaped slot line including an inner conductor and an outer conductor, an electric boundary point set on the slot line, a two-port negative resistance element for connecting between the inner conductor and outer conductor, and an output line electrically connected to the slot line. The electric boundary point is set by connecting, for example, a stub to the resonator circuit. The stub functions as an electrically short-circuited end or an electrically open end. A Gunn diode is preferably used for the negative resistance element, and inserted at a position of the slot line resonator circuit at which impedance matching is achieved.

Abstract: A multi-element planar array antenna has a substrate made of a dielectric material or the like; a planar conductor formed on a first principal surface of the substrate; a first and a second slot line formed in the conductor and intersecting each other; a first and a second microstrip line formed on a second principal surface of the substrate, and traversing the first slot line respectively at positions corresponding to both end sides of the first slot line; a third and a fourth microstrip line formed on the second principal surface, and traversing the second slot line respectively at positions corresponding to both end sides of the second slot line; and four slot line antenna elements formed on the first principal surface respectively in intersection regions between both end sides of the first and second microstrip lines and both end sides of the third and fourth microstrip lines.