A Survey of 1200-1800 MHz using a Discone and a Spiral with the Argus Front End

This document reports on a survey of radio frequency interference (RFI) in the band 1200-1800 MHz. The survey was conducted during business hours from the roof of the Ohio State University ElectroScience Laboratory (ESL), using two antennas. One antenna was a commercially available wideband discone antenna, which is weakly directive along the horizon, and has directivity ¿ 1 toward the sky. The other antenna was a planar spiral, which has a complementary pattern (directivity ¿ 1 toward the horizon, weakly directive toward the sky). The resolution of the survey is 1 MHz and the system temperature Tsys ∼ 360◦K, resulting in a nominal “snapshot” sensitivity of about −110 dBm/MHz against an antenna temperature TA ∼ 290◦K (i.e., ∆T ∼ 650◦K). After 1 hr, ∆T is reduced to about 5.3◦K, allowing detection of signals as weak as −131 dBm/MHz provided that they are stationary. A “max hold” technique is also used to enhance sensitivity to strong, low-duty cycle signals, such as pulsed-CW radars. The results presented here represent the best characterization of the RFI envirnoment in the ESL area obtained so far. A number of known RFI sources – both strong and weak – are identified, and the presence of weak, impulsive spurious RFI is identified. Fortunately, the latter is found to be predominately terrestrial in origin; ∗The Ohio State University, ElectroScience Laboratory, 1320 Kinnear Road, Columbus, OH 43210, USA. Email: [email protected].