Radio frequenc surve of the 21-cm wavelength (1.4 GHz) allocation for passive microwave observing

Because of the need to develop 1.4-GHz ra- diometers, a set of RF surveys was conducted in and around our laboratories. In this paper, a measurement campaign and analysis of radio frequency interference (RFI) in the 21- cm wavelength allocation for passive microwave observing, was undertaken. The experimental setup and measurement procedure are outlined and measured data are interpreted. Significant signals were discovered within and surrounding the allocated spectrum at 1.4 GHz. Some implications for remote sensing are discussed. I. INTRODUCTION