Using VNAs to test OTA RF/μW shielding and propagation on large vehicles generally requires very long test port cables to reach around the vehicles. At the distances required for these tests, coax cables to introduce insertion loss and phase instability so significant that different transmission media (such as optical cabling) must be used to enable S-parameter measurements. The additional hardware and setup complexity significantly raises the cost and time required to make the propagation and shielding measurements.
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