In the framework of the project «Antennas for Underground Communications», a prototype antenna has been validated in a vacuum enviroment, at a operational temperature between -20⁰ to 60⁰C. This test has been carried out in the facilities of the Universidade Vigo.  A electromagnetic absorber made of Ecosorb ( » test cap») surrounded the antenna.

The antenna under test (AUT) is attached to the baseplate through the interface support. Once the antenna-support-baseplate assembly was bolted, a total of 12 thermocouples were attached on the baseplate, the interface and the AUT.   

Four thermal cycles have been carried out, measuring the reflection coefficient every two minutes. During these cycles, the antenna reflection coefficient was monitored. The results for the third cycle (as an example) are shown bellow. In all cases, the minimum of the reflection coefficient remains at 2.4 GHz, with small variations. The antenna bandwidth remains at 150 MHz ± 10 MHz, greater than the required bandwidth for this antenna (100 MHz).