The G-TEM first saw use as an EMC test device in the U.K. about 1990 and rose quite rapidly in popularity through the early and mid-nineties. At the time it offered a viable and cheaper alternative to the semi-anechoic chamber. Its fault was that it had been over marketed as an end-all to a lot of the drawbacks associated with both OATS and larger chambers.
Nevertheless, those in the established EMC community whose wrath it had incurred were quick to disclose its shortcomings. However, once the operator became aware of its strengths & weaknesses and the EUT size was kept well within the permitted volume under the septum then some fast & reasonably accurate data could be produced. From the outset it had two very distinct attractions. The first being its linear relationship between input power and field strength over the frequency range for immunity testing. That brought down the cost of the RF amplifiers. And the second advantage was the elimination of the customary antennas with their height scans & groundplanes. This advantage was later to be eclipsed by the advent of the Fully Anechoic Chamber. The problem area was that any associated cabling of the EUT effectively & considerably enlarged its size in proportion to the permitted volume allowed under the septum. In short, if you were testing a battery laptop it was absolutely ideal but more complex pieces of EUT required a very careful layout procedure.
Because of their compactness and understanding of operation EMCH has two of these GTEMs on inventory. A small 5305 version with just a half metre clearance under the septum restricting test items to no more than about 18cm cubed. It is this item that can be hired & transported to the customer's premises for prolonged use, typically accommodated in loading bays. Along with the GTEM, a complete suite of emission & immunity test gear can be provided including a PC with software. All of this is offered under items 920-923. An engineer will accompany the delivery & remain until the end user is confident with the software & general handling. The minimum hire period is one week due mainly to transportation costs and lost time delivering. Typically it arrives somewhere around mid day depending where you're based & we would collect mid to late morning on the day of retrieval. Price is structured around just what extra equipment you require.
On the immunity side, the GTEM affords itself well to increased levels of
RF field by not only applying a larger amplifier, but provided the EUT size
is small, placing it further down the cell towards the feed end thus incurring
a stronger field.
At present in the UK there exists an active & vibrant "GTEM User Group" who for the last eight or so years have met three to four times a year to critically discuss techniques, share experiences and knowledge. They also provide an input to the various committees implementing test methods & procedures.