Oxley products for defence platforms have to be tested to military standards, which are far more stringent than commercial or industrial EMC testing. Oxley typically test to MIL-STD-461, RTCA/DO-160 and DEF STAN 59-411. These tests involve accurate measurement of very low radio frequency levels for emissions testing up to 40GHz and very high radiated fields for susceptibility.
Although there are plenty of external test labs where the work could be carried out, there are none in the north of England capable of testing to the high levels many Oxley products must meet. “We’ve been spending a lot of time and money travelling to suppliers to carry out our EMC tests.” said Oxley Technical Manager (Electronics) Mark Jordan, “So getting our own EMC test facility up and running is something I’ve been pushing for and it will be a huge asset for Oxley.
“At present we spend over £90K per year on external testing in Dorset. If the test fails we’ve lost time and money for nothing. Now our electronics engineers can test products in-house all the way through their development and be sure that they will pass when they are fully developed.
“We’ll be carrying out emissions, susceptibility and qualification tests, and we’ll be gradually adding new equipment to increase our testing capabilities.”
Anechoic means ‘without echoes’. The walls of the chamber are covered with pyramidal panels which reflect energy into the apex, dissipating it in the material instead of the air. The panels are typically made from rubberised foam impregnated with carbon, designed to absorb incidental radio frequencies as effectively as possible from as many directions as possible. The chamber is built into a screened room, because most of the EMC tests that require an anechoic chamber to minimize reflections from the inner surfaces also require the properties of a screened room to attenuate unwanted signals penetrating inwards and affecting the equipment test measurements.