GB613927A - Improvements in or relating to radio communication systems - Google Patents

Abstract

613,927. Aerial coupling arrangements; multiplex radio signalling. YEO, R. A., WATSON, A. G. D., JONES, J. H., and WRIGHT, C. S. Sept. 29, 1945, No. 25340. Drawings to Specification. [Class 40 (v)] Several transmitters or several receivers tunable over a band of frequencies are conconnected to a common aerial through arbitrary lengths of transmission line, each of which is shunted by a single-adjustment tunable filter tuned to the frequency of its associated transmitter or receiver and located at a distance from the common junction which is effectively one-quarter wavelength at a frequency within said band, the lines between each filter and the junction acting as an impedance converter for all frequencies in the band. In a system with three transmitters or receivers using different fixed frequencies in a single band, the filters are sharply tuned and the quarter-wave feeders are referred to the sum of the wavelengths of 'the other two transmitters or receivers less the wavelength of the associated transmitter or receiver. In another system with two or more transmitters or receivers using different fixed frequencies in a single band, the filters are sharply tuned and the quarter-wave feeders are referred to the average frequency of the other transmitters or receivers or the mean frequency of the range of frequencies thereof. Two or more groups of transmitters and receivers working in distinct frequency bands and connected as already described may each be connected to the common aerial through a band-pass filter covering the frequency range of the associated group, connected in series with a quarter-wave feeder based on the mean or average of the average frequencies of each of the other groups, or the mean or average of the mean frequencies of the range of frequencies of each of the other groups.