Derek Gray

Assessment of Sochacki lenses for autonomous maritime patrol FLAR

Initial numerical and experimental results are given for minimal layer lens antennas for Forward Looking Airborne Radar as the primary sensor onboard small Unmanned Aerial Vehicles adapted for fully autonomous long distance maritime patrol. 27dBi was achieved by a single material lens that is dimensionally compatible with the fuselage of a 6-meter class Unmanned Aerial Vehicle. Numerical results for 2 and 3 layer lenses up to 38dBi directivity were given, been comparable to the reflector antennas presently used in P-3C and P-8A manned maritime patrol aircraft.

Structural slotted waveguide antennas for multirotor UAV radio altimeter

Z-slots are presumed to offer a structural advantage over conventional inclined slots for narrow wall slotted waveguide antennas, in that the corners of the rectangular waveguide are not cut and consequently will not weaken a structural tube as much. Initial structural simulations are shown to confirm this assumption. This slot configuration was also further investigated as radiating slots in standing wave type slotted waveguide antennas. Fan-beam antennas having 10 to 30 slots were successfully designed for 10GHz using a commercially available antenna simulator, having directivities from 16 to 21dBi and aperture efficiency of 60%.

Vivaldi antenna for railway cutting monitoring

A planar Vivaldi antenna was reconstructed and assessed as a candidate for a short range, high range resolution railway cutting monitoring radar. The initial flare section of the Vivaldi antenna was found to control the return loss of this type of antenna at lower frequencies, and a compact antenna for 120% fractional bandwidth was demonstrated experimentally. Group delay was used as a UWB antenna assessment method, and the prototype antenna gave reasonable performance across the lower half of the band considered.

Effect of aspect ratio on TE 01δ mode DRA

A lowest order magnetic dipole mode isolated cylindrical DRA was investigated experimentally and using the surface equivalence principal and finite element method solvers in a commercially available software. The height to radius ratio of these DRAs for a fixed resonant frequency was found to vary non-linearly, as predicted by prior theory. An initial 30mm high, 15.4mm radius horizontally polarized DRA was prepared for 2.3GHz band licensed video communications from a small UAV to ground station.

Examination of Watson's microwave yagi aerial

A historical 34-slot travelling wave, end-fire rectangular waveguide antenna that has not been previously qualified is examined using a commercially available software. Structurally, this antenna has some advantages over other travelling or leaky-wave antennas that could be used for 24GHz ISM band radar onboard a multirotor UAV, due to the all metal construction. The radiation pattern characteristics of the published antenna design were a peak directivity of 16.2dBi with 1dB directivity bandwidth of 12.2%.