Fig 1.
Antenna’s radiation pattern obtention methods: Conventional (left, the ship circles and a probe antenna stays in the coast) and alternative (right, the vessel is static at sea and a UAV circles it).
Fig 2.
Correction factor that should be applied to the estimated gain if radial distance deviation from the theoretical path exists.
Fig 3.
Far field distance as a function of antenna's dimension for different wavelengths.
Fig 4.
The two possible flight heights of the UAV and their influence on the clearance of the first Fresnel ellipsoid.
Fig 5.
The first Fresnel's ellipsoid radius (flight level) for different frequencies.
Fig 6.
Multipath issue based on the two-ray ground-reflection theory.
Fig 7.
Received power at f = 900 MHz, having hAUT = 2 m and hUAV = 50 m.
Fig 8.
Avoidable and recommended measurement zones due to multipath effect (f = 900 MHz, hAUT = 2 m, hUAV = 50 m).
Fig 9.
UAV's received signal power in AUT environment (0–800 m range).
Fig 10.
UAV's received signal power in AUT environment (detail on 300–600 m range).
Fig 11.
Circular trajectory calculated for lateral guidance.
Fig 12.
Polarization vector evolution at receiving antenna when a UAV is rolling (rotating with respect to the x axis).
Fig 13.
Roll angle evolution and decoupling losses due to rotation with respect to the x axis.
Fig 14.
Polarization vector evolution at receiving antenna in a real flight.
Fig 15.
Decoupling losses in a real flight for pitch and roll motions.
Table 1.
F100 class main dimensions and equipment.
Table 2.
Minimum flight distance according to criteria.
Table 3.
Minimum flight distance according to criteria (reduced version).
Fig 16.
Multipath scenario for f = 300 MHz, hUAV = hAUT = 21.5 m.
Fig 17.
Power received in a multipath scenario for f = 300 MHz, hUAV = hAUT = 21.5 m.
Table 4.
First Fresnel’s ellipsoid height for hUAV = hAUT = 21.5 m.
Table 5.
Radius, flight level and measurement uncertainty for F-100’s class Spanish Navy frigates’ antenna.
Fig 18.
Pitch and roll angle evolution for a 10° polygonal flight at v = 1 m/s, radius 50 m.
Fig 19.
Pitch and roll angle evolution for a trajectory guided circle path, at v = 1 m/s, evel = 0.2 m/s and R = 50 m.
Fig 20.
UAV carrying the proposed measurement system: Vertical antenna and software radio receiver.
Fig 21.
Polarization decoupling losses vs time for a polygonal flight under 10° resolution, 1 m/s ground speed and R = 50 m.