Radiated emission tests are usually performed in anechoic chambers, using antennas to pick up the radiated signals.
Due to bandwidth limitations, multiple antennas are required to cover the entire frequency range. In addition, it requires a lot of space and the cost of the equipment for a standard-compliant installation is enormous.
An engineer in a small or medium-sized company usually has to rely on his experience and on best practice methods to design an EMC compliant product.
Nevertheless, it is estimated that > 50% of products fail the first time testing. Every time an engineer sends a new product for conformance testing, it's a shot in the dark.
Failure is very expensive. Not only are the costs of retesting high, but also the project schedule and market introduction are delayed.
What is needed is an affordable laboratory set up to measure radiated emissions in the in-house lab, prior to compliance testing.
A TEM cell is the right equipment for stationary tests of radiated emissions. Tekbox developed open TEM cells to cover the entire frequency range up to 2GHz and with usability at frequencies beyond.
In combination with a spectrum analyzer, products can be tested before and after EMC-related design changes.
A setup with a TEM cell will not deliver the exact same quantitative results as a measurement in a certified test house, but it will give an excellent indication of whether or not the design suffers from excessive radiated noise.
The engineer will clearly see if his changes improved or degraded the EMC performance or if it remained unchanged. Using TEM cells eliminates the guesswork.
A TEM cell consists of a septum, the conductive strip in the center section, and walls that are connected to ground. The geometry is designed to present a 50Ω stripline. The device under test (DUT) is placed between the bottom wall and the septum.
TBTC1/2/3 are so-called "open TEM cells", which have no side walls for convenient DUT placement.
It can pick up RF background noise, however, which can be accounted for by making a measurement of the cell output signal before turning on the DUT.
Tekbox open TEM cells had a better frequency response compared to standard TEM cells of similar size.
TEM cells suffer from higher order wave modes that limit the usable bandwidth. A unique design feature of Tekbox TEM cells implements resistance perpendicular to the desired wave propagation direction.
Consequently, wave modes and higher order resonances are suppressed.
All TEM cells are supplied with a 50Ω/25W RF termination, a DC block to protect the spectrum analyzer or RF receiver input and an N-male to N-male coaxial cable.
