Question: What is the primary cause of phase curvature uncertainty in Over The Air (OTA) antenna performance conformance testing for User Equipment (UE)/Mobile Station (MS), and at what frequency does a measurement distance of 1.5 meters correspond to negligible error, assuming a threshold of 10λ?
Option 1: Insufficient calibration; 1.5 meters corresponds to negligible error at approximately 400 MHz.
Option 2: Finite far-field measurement distance; 1.5 meters corresponds to negligible error at approximately 2 GHz.
Option 3: Environmental interference; 1.5 meters corresponds to negligible error at approximately 800 MHz.
Option 4: Inadequate anechoic chamber size; 1.5 meters corresponds to negligible error at approximately 6 GHz.
Explanation: The primary cause of phase curvature uncertainty in OTA antenna performance testing is the finite far-field measurement distance, introducing errors due to spherical wavefront's curvature. A distance >10 times the wavelength (10λ) makes this error negligible. At 2 GHz, λ ≈ 0.15 meters, so a 1.5 meters distance (10 * 0.15 meters) corresponds to negligible error at this frequency, crucial for accurate conformance testing in telecom environments.