Unmanned aerial system for antenna measurement and diagnosis: evaluation and testing

Abstract

This contribution analyses the performance of an unmanned aerial system for antenna measurement (UASAM) for different kinds of measurement scenarios. UASAM is conceived for antenna diagnostics and characterisation at the operational location of the antenna under test (AUT). The system measures the amplitude of the near field radiated by the AUT. Then, these measurements are post-processed using phase retrieval techniques and equivalent currents methods to obtain an electromagnetic model of the AUT. This model can be used for antenna diagnostics and for evaluating the far field pattern. Similar to antenna measurement systems in anechoic chamber, UASAM allows defining different acquisition grids depending on the type of AUT (planar, cylindrical, arc cylindrical), which also influences the flight time. In addition to this, the capability to measure circularly polarised antennas from amplitude-only measurements is presented, discussing the limitations found during the tests, and comparing the results with those from measurements at a spherical range in an anechoic chamber.

Dual-Probe Near-Field Phaseless Antenna Measurement System on Board a UAV

“…As explained in Section 1, the system proposed in [9,11,20] makes use of the NF measurement data collected on two or more surfaces surrounding the AUT. These measurements are post-processed by means of phase retrieval techniques to recover phase information.…”

“…As explained in [9], there are some restrictions for the direct measurement of the FF pattern using UAVs, namely safety restrictions (forbidden flight areas) and UAV flight autonomy. These issues can be overcome if the measurements are carried out in the near field (NF) region of the AUT, so that the furthest distance from the AUT to the UAV is not greater than 10–20 m. The feasibility of NF measurements using UAV-based systems has been proved in [9,10,11,12].…”

“…In [9,11,20], an UAV-based system for on-site antenna measurement was presented, assessing the performance of the implemented system for antenna diagnostics and characterization. This contribution presents several novelties to improve the measurement accuracy of the system, thus enabling the characterization of high directive antennas, such as reflectors.…”

Impact Analysis and Calibration Methods of Excitation Errors for Phased Array Antennas

“…These calibration methods vary from different systems and applications, either suitable for factory test or for in-field test [41]. Some methods such as the near-field scanning probe method and the peripheral fixed probe method require additional equipments [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], while the mutual coupling method takes advantage of the inherent property of the phased array without the need for extra hardware [61][62][63][64][65][66][67][68][69][70][71]. For Si-based integrated phased array antenna, it's very common to design a dedicated coupling network that using transmission lines connected to each antenna element for periodic in-field calibration [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86]…”

UAV-Based Antenna Measurements for Polarimetric Weather Radars: Probe Analysis

“…In this context, [21] explored sampling the near field (NF) radiation surrounding the AUT to overcome the FF distance limitations. For telecommunication, [18], [23] and [25] presented a compact, low-cost system for S-and Cbands, capable of centimeter-level accuracy, by sampling the NF (near field) radiation and using a combination phaseless sources reconstruction method and NF-to-FF transformation to obtain the measured FF radiation patterns, with a brief analysis of the impact of the selection of the probe antenna for NF measurements. Then, [26] further improves on these achievements by adding an extra probe and increased positioning accuracy with a dual-band RTK GNSS.…”