A Fully Dielectric Lightweight Antenna Array Using a Multimode Interference Power Divider at W-Band

In this letter, we present a fully dielectric antenna array for the first time, including a single multimode interference power divider as feeding network. This allows a lightweight and compact antenna design in single dielectric waveguide technology since a cascading of multiple power dividers is avoided. Furthermore, the use of a single power divider instead of several cascaded ones reduces parasitic radiation, which occurs at discontinuities, such as bends or curvatures of dielectric waveguides. As demonstrator, we present a 1 $\times$ 4 antenna array fed by a single, four-port, multimode interference power divider, operating in the frequency range from 85 to 105 GHz. It is made from a single sheet of cross-linked polystyrene Rexolite. Each antenna element of the array consists of a tapered dielectric rod antenna of rectangular shape. In the measurements, the antenna array exhibits a half-power beamwidth of 12° in the H -plane and a gain of 16.9 dBi at 95 GHz accompanied by a sidelobe level of around $-$ 11 dB. The antenna array shows a good matching with a return loss higher than 15 dB in the desired frequency range.