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

Abstract

One of the principal challenges in the calibration of polarimetric weather radars is achieving the strict requirements in the measurement of the antenna radiation pattern of the system; e.g., a copolarization mismatch of at most 0.1 dB, and cross-polarization levels less than approximately −40 dB are highly desirable. In a UAV-based antenna pattern measurement system, the radiation characteristics of the probe antenna can be adversely affected by scattering off of the UAV platform itself, and by the relative orientation of the probe antenna with respect to the UAV frame. It is hypothesized that such extraneous reflections depend on the type of antenna used as a probe, and in this context, a more directive probe antenna (i.e., with low back lobe radiation) would be necessary to achieve the required measurement accuracy for weather radar applications. This work studies the effect of UAV and probe antenna interaction for different types of antennas through EM simulations, and this is validated with chamber measurements. For the patch array antenna under study, co-polarization mismatch levels of approximately 0.13 and 0.05 dB, and maximum cross-polarization levels of −37 and −34 dB, are achieved at boresight in measurements and simulations, respectively, which can be improved to meet the requirements with a careful selection of the gimbal operating angle range. INDEX TERMS antenna characterization, co-polarization mismatch, cross-polarization contamination, dual-polarized, far-field, measurements, probe, UAV interaction, weather radar.

Electromagnetic Compatibility Analysis of Quadcopter UAVs Using the Equivalent Circuit Approach

“…This radiating antenna is typically used to characterize the radiation characteristics of receiving devices on the ground. The effect of the UAV on the radiation characteristics of the antenna in its payload has been reported in several studies = [12], [59], [61]. However, in this work, we are studying the effect of the payload on the coupling to the carrying UAV.…”

“…Several studies have reported the use of radiating antennas in the payload of a UAV [8], [10], [12], [58]- [60]. This radiating antenna is typically used to characterize the radiation characteristics of receiving devices on the ground.…”

“…NMANNED Aerial Vehicles (UAVs) have been proposed for a wide range of applications due to their low cost, easy operation, and high mobility [1]- [7]. Moreover, UAVs have been studied to fly near antennas on the ground and calibrate/characterize their radiation patterns in various applications [8]- [12]. Therefore, extensive research has been conducted to improve the operation of UAVs in different environments and for different applications [13]- [17].…”

A Cost-Effective Tethered-UAV-Based Coherent Near-Field Antenna Measurement System

“…That minimizes the moment of inertia and ensures good maneuverability. However, mounting the probe antenna close to the gravity center has the consequence that the drone frame and propellers affect the probe radiation pattern [55]- [57] and, thus, also the field measurement results as observed in [10]. To overcome this drawback of commercially available UAVs, a custom drone frame as shown in Fig.…”

A Cost-Effective Tethered-UAV-Based Coherent Near-Field Antenna Measurement System

“…That minimizes the moment of inertia and ensures good maneuverability. However, mounting the probe antenna close to the gravity center has the consequence that the drone frame and propellers affect the probe radiation pattern [54]- [56] and, thus, also the field measurement results as observed in [10]. To overcome this drawback of commercially available UAVs, a custom drone frame as shown in Fig.…”