Single layer adaptive plane array antenna and variable reactance circuit

A single-layer adaptive plane array antenna device mounting an antenna array unit mounting an active antenna element and two or more passive antenna elements and two or more variable reactance circuits each of which is connected to each of the passive antenna elements and changes each reactance of a signal supplied to each of the passive antenna elements, on the same printed-circuit board, wherein

• the variable reactance circuit includes
• a variable capacitance circuit controlled by bias voltage;
• a resonating folded line bias circuit having an AC grounding node for supplying the bias voltage to the variable capacitance circuit, for transmitting the bias voltage to the variable capacitance circuit including a thin line interconnecting spacer for transmitting the bias voltage to the variable capacitance circuit side and first and second open folded stubs each of which is connected to the thin-line interconnecting spacer, each of which is also disposed in parallel with a longitudinal direction of each other in a prescribed small gap with the thin line interconnecting spacer, each of which has a folded shape and each of which functions as an inductance element and a capacitance element respectively, in order to form a resonant circuit for realizing the AC grounding node;
• and
• an impedance transformer circuit for separating the variable capacitance circuit from the AC grounding node.