New trends in planar antenna research

New antenna concepts are reviewed and discussed. The main focus of this review paper is on some recent activities by the authors at the Royal Military College of Canada and Queen´s University in Kingston. Topics include surface-wave launcher (SWL) sources for novel feeding of quasi-optical circuits and new planar antennas at millimeter-wave frequencies. In these configurations, a bound cylindrical TM₀ surface-wave (SW) mode is excited on a grounded dielectric slab (GDS). Planar antenna designs include leaky-wave antennas (LWAs) for pencil-beam, conical-sector and broadside radiation. In addition, end-fire radiation is also possible by reshaping the ground plane realizing a novel surface-wave antenna (SWA). Arrayed placement of such SWLs can also achieve SW beam steering on the guiding surface. By varying the relative phase difference or effective weighting distribution between SWL elements, the generated SW field distribution can be steered and controlled. Using such a novel SWL array, far field beam patterns can be shaped and controlled at a single frequency. These SWLs offer new possibilities for planar antenna feeding systems and novel circuit configurations.