My group was involved with the design, prototyping, and
measuring of a fixed dual-band cellular antenna described in
patent no. 5,963,170. In order to test the antenna pattern in
the anechoic chamber, the fixed dual-band antenna had to be
mounted on the cellular phone housing with a semi-rigid 50-ohm
cable connected to the matching circuit on the printed wiring.
The phone was not powered, since the matching circuit was
disconnected from the output power amplifier so that the cable
could be attached. Now this semi-rigid cable went down to the
azimuth positioner and connected to a coaxial slip-ring joint.
The opposite side of this slip-ring joint then had an RF cable
connected to a spectrum analyzer outside the chamber. The
chamber consisted of square-based pyramidal absorbing material
attached on all sides that absorbed the RF transmitting signal
from a standard antenna mounted in the chamber. The thin semi-
rigid cable from the phone to the rotating floor was covered
with a tube of the same absorbing material