Frustum-Shaped Conformal Antenna Array for Air-to-Ground Communication

In this work, a frustum-shaped conformal antenna array for Direct Air-to-Ground Communication (DA2GC) is designed and studied. The requirement calls for an omnidirectional radiation pattern, however the simple monopole or dipole is constrained only to the azimuth plane/yaw and might have deep null in elevation plane due to the aircraft body effect. This work proposes an eight elements conformal array operating at C band frequency covering 4.4 to 5.0 GHz, whose substrate has the shape of a frustum, which provides a solution that meets all the requirements. This design achieves less than 5 dB gain variation across azimuthal coverage and ensures sufficient gain at shallow elevation angles. A passive conformal array on a frustum fed with a microstrip-based $1: 8$ power divider design with results are presented first. Later, an active conformal array with switchable beam is explained. Further, a comprehensive analysis of implementation brought out, indicating that the proposed will be better switchable sectoral coverage is acceptable. This analysis also indicates that the active array configuration requires reduced power due to the increased gain of the array and as it covers only a sector at a given time.