Low-cost omnidirectional planar antennas for the 122 GHz ISM frequency band

The first planar monopole antennas for the ISM frequency band at 122 GHz have been presented. Fabricated prototypes are broadband (up to 11 GHz bandwidth) and provide omnidirectional radiation patterns. Simulations and measurements have shown that the ground plane geometry has a big influence on the radiating characteristics of the antenna. In addition an enhancement of bandwidth can be achieved by a tapered line feeding. Because of the directly fed structure and the small dimensions, the antennas are well suited for future applications. Several elements of the proposed antennas could be integrated easily together with other circuitry to enhance the transmission characteristics of a single wireless device.