Spurious radiation from microwave ovens

Abstract

In agreement with the regulations of the International Telecommunication Union the manufacturers of microwave ovens are licensed to operate within the frequency band 2.45±0.05 GHz reserved for industrial, scientific and medical purposes. Evidence that microwave ovens emitted significant amounts of radiation outside this licensed band and covering the reserved bands allocated to radioastronomy and communications was given in a report prepared for the Royal Society and Ministry of Technology in 1969¹. No action was taken by the licensing authorities to enforce restrictions on this spurious radiation and because the use of microwave ovens has become widespread we have made and report here a new series of measurements to assess the extent of this radiation from the ovens now in use. Our main concern has been with the spread of the oven radiation into four of the bands protected internationally for the use of radioastronomers: 1,400–1,427 MHz (21 cm H-line band); 1,660–1,670 MHz (18 cm OH band); 2,690–2,700 MHz (11 cm S-band); 4,990–5,000 MHz (6 cm C band). Although our primary interest has been to estimate the limitations which may be placed on the performance of the radio telescopes at Jodrell Bank by microwave ovens used in the vicinity, the results are relevant to the communication systems that are allocated nearby frequency bands.