Radiation characteristics of sharply directed conical waveguide-slot antenna arrays

Currently, much attention is paid to antenna arrays, the emitters of which can be located in the bow of unmanned aerial vehicles (UAVs). Emitters can be longitudinal, transverse or oblique slots located along the generatrix of the cone on the conducting surface. A number of specific requirements are imposed on such ARs used in on-board radar systems (radars) of UAVs, among which we can note the need to form a highly directional total-difference directional pattern (DP) with a maximum of the total DP and a minimum of a difference DP in the direction of the UAV flight axis, as well as high gain and slope of the difference characteristic. The aim of this work was to study the radiation of a waveguide-slot antenna array (WASAA) installed on a conical surface and providing linear polarization of the emitted field in the direction of the cone axis. For this, electrodynamic modeling of various configurations of WASAA, located both in free space and on a conical surface, was carried out. For the developed models of antennas, the directivity characteristics and their dependence on the geometry and dimensions of the WASAA are determined. The results of an experimental study of the characteristics of a model of a conical antenna emitting a field of linear polarization in the direction of the cone axis are presented. The experimental results are compared with the results of electrodynamic modeling. The results obtained are of practical interest for the development of airborne antenna UAVs.

A Ka-Band Circular Polarized Waveguide Slot Antenna with a Cross Iris

A Ka-band circularly polarized (CP) waveguide slot antenna with a cross iris is proposed. To achieve the CP characteristic (LHCP) in the antenna, a hexagonal shaped cavity is used. The impedance matching is improved by adjusting the sizes of the hexagonal cavity and a rectangular matching cavity. To enhance the axial ratio bandwidth, a cross iris is used with two arms of different lengths. From experimental results, the proposed antenna has a 3 dB axial ratio bandwidth of 6810 MHz (31.72 GHz–38.53 GHz). The −10 dB reflection coefficient bandwidth of the proposed antenna ranges from 31.51 GHz to 39.21 GHz (7700 MHz).