A ground electrode is formed on the lower surface of a ferroelectric substrate, a control electrode including capacitor electrodes and an inductor electrode is formed on the upper surface of the ferroelectric substrate, and an upper-surface radiating electrode and an end-surface radiating electrode are formed on a paraelectric substrate. The shapes and dimensions of the ferroelectric substrate, paraelectric substrate, and radiating electrodes are determined such that when the ferroelectric substrate and the paraelectric substrate are stacked in layers, a circuit including the radiating electrodes resonates at frequencies outside a frequency band exhibiting frequency dispersion of a dielectric constant.