A planar zeroth-order resonator antenna using a left-handed transmission line

A novel planar antenna based on the zeroth order resonator (ZOR) which resonates with an infinite wavelength is studied. Since the resonant frequency of the ZOR antenna is determined not by the physical resonator length hut by LCvalues loaded in the resonator, the antenna size can he arbitrary regardless of the operation frequency and, therefore, one can have I freedom in radiation pattern design. A small-sued four-unitsell ZQR antenna with 75% foot print area reduction compared with a conventional patch antenna with a broad radiation pattero is demonstrated at 4.88 GHz with a broad radiation.