Realization of a communication experiment at 500-GHz band

As a new attempt to expand wireless transmission channel bandwidth, a submillimeter-wave communication experiment has been carried out by using techniques of frequency multiplication of millimeter-wave signal source and high-sensitivity superconducting SIS (Superconductor-Insulator-Superconductor) receiver. The transmitter consists of a 500-GHz frequency quintupler and a 93-GHz varactor-tunable Gunn oscillator with its output frequency modulated via a 10-14 MHz signal source, while the 500-GHz SIS receiver has an IF (Intermediate Frequency) band of 1.1-1.7 GHz and an overall system noise temperature below 400 K. A theoretical analysis is given to prove the principle and engineering feasibility of the experimental communication system. The measured spectra of the received FM (Frequency Modulation) signals with modulation frequencies of 10-14 MHz on a downconverted IF carrier of 1.6 GHz show that effective direct frequency modulation on a transmitting submillimeter-wave carrier of 466 GHz and the reception of the submillimeter-wave FM signals by the 500-GHz SIS receiver have been successfully realized.