Investigation of aircraft generated VLF interference

Reception distances of VLF/LF transmissions, on board the KC-135 aircraft, have been severely restricted by electromagnetic interference generated by the aircraft's equipment. This interference has prevented the accurate measurement of propagation data at distances greater than 1,000 miles when using the aircraft's omnidirectional antenna. With the use of a directional loop antenna mounted on the aircraft's boom, reception distances of up to 6,000 miles have been attained. The restriction of directionality prevents measurements along paths which are of great importance to the MEECN. The reduction of aircraft interference for VLF/LF reception is of paramount importance to the Air Force and the success of this segment of the Tri Service Propagation Program is also important. This report describes the investigation of the VLF aircraft generated interference by RADC giving the characteristics of the noise in both the frequency and time domains.