Reflector Analysis for Novel OTA Test Method

The use of millimetre waves (mmWaves) have required the design of novel OTA test methods. A low-cost OTA methodology based on elliptical cylindrical reflector takes advantage of the reflective properties of the ellipse to perform conformance test of devices operating at mmWaves. Two types of flat reflectors have been compared to quantify the effect that deformations in their surfaces, in the order of millimetres, produce in the reflected signal at 24 GHz. The signal amplitude reflected from a copper substrate reflector, with a total height variation (THV) in its surface of 2.73 mm, is 3.2 dB lower than the signal amplitude reflected by a rigid certified (reference) aluminium cast tooling plate with a THV of 0.46 mm under the same conditions. In addition, the half power beamwidth (HPBW) of the reference reflector is 1° smaller than the HPBW produced by the substrate plate.