Design and Fabrication of a Model Launch Fairing for EMC Measurements

A launch vehicle payload fairing scale model has been designed, fabricated, and tested to investigate the reverberant electromagnetic fields within launch vehicle fairings. The fairing scale model uses a mechanical stirrer to attain statistically uniform fields within the fairing cavity. A removable payload model and payload adapter model are included in the fairing to study the interactions of fields with these structures. The layering of the fairing walls, use of shielding gaskets, and field probes to measure the cavity fields are described. The quality factor is measured when the fairing cavity is empty and when the surrogate payload and payload adapter models are added. The quality factor of the empty fairing measured from about 32 dB at 1 GHz to 41 dB at 6 GHz. The Q values dropped approximately 2 dB across the band when the payload and payload adapter models were placed in the fairing cavity. Measurements of Q at different probe positions within the fairing yielded similar results.