TekBox TBTC2 TEM Cell

Engineers often have to rely on experience and on best practice methods in order to design an EMC-compliant product. But > 50% of products fail testing the first time around. Failing is very expensive. Not only that, re-testing costs are high, and the project schedule and market introduction gets delayed. What is needed is an affordable laboratory set up where engineers can measure radiated emissions in their own lab prior to compliance testing. A TEM cell (Transverse ElectroMagnetic Cell) is the best piece of equipment for desktop testing of radiated emissions. The TekBox TBTC2 TEM Cell was developed to cover the complete frequency range up to 2GHz and with usability even at frequencies beyond.

Combined with a spectrum analyzer, products can now be tested before and after EMC-related design modifications.  A set-up with a TEM cell will not deliver exactly the same quantitative results as a measurement in a certified test house, but it will give an excellent indication of whether the design suffers from excessive radiated noise or not.  The engineer will clearly see, whether changes improve or worsen the EMC performance or remain unchanged. The TBTC2 eliminates the guesswork.

A TEM cell is a stripline device for radiated emissions and immunity testing of electronic devices. It is not a replacement, but due to its size and cost it is a convenient alternative to measurements in an anechoic chamber.

A TEM cell consists of a septum, the conductive strip in the center section and walls which 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.

The TBTC2 is a so called “open TEM cell” which has no side walls for convenient placement of the DUT. It may pick up RF background noise, but this can be taken into account by doing a “null” measurement of the cell output signal before powering on the DUT.

The TBTC2 has a better frequency response compared to most standard TEM cells of similar size. TEM cells suffer from higher order wave modes which limit the usable bandwidth. A unique design feature of the TBTC2 implements resistance perpendicular to the desired propagation direction of the wave. Consequently higher order wave modes and resonances are suppressed.

The device is supplied together with a 50Ω/25W RF termination and a DC block to protect the spectrum analyzer or RF receiver input.