GB529539A - Systems for transmission of electromagnetic waves at very high frequencies - Google Patents

Abstract

529,539. Signalling through dielectric guides. STANDARD TELEPHONES & CABLES, Ltd. June 2, 1939, No. 16283. Convention date, June 29, 1938. [Class 40 (iii)'] A dielectric guide or transmission line is characterized by the provision of a filter element which allows the passage of a selected type of ,wave and stops all others. As shown in Fig. 2, the filter element is a quarter wave-length long and is terminated at each end by a network 3 of wires which are arranged transverse to the guide 10 so that they run in the same direction as the electric lines of force of the wave or waves to be stopped. This applies for instance to an electric wave of the type Eo, and also a magnetic wave of the type Ho, where the electric and magnetic lines of force respectively run parallel with the end wires. On the other hand the filter will pass a wave in which the lines of force are at right-angles to the network. Parasitic waves a, b, c, generated by the transmitter 5, Fig. 5, may, for instance, be blocked out by inserting a series of filter elements 1, 2; 2, 6; 6, 7, of appropriate length. In Fig. 6 an aerial 8 is attached to one filter network so as to radiate the stopped frequency. A succession of filters may also be used to eliminate any undesired wave-forms caused, for instance, by deformations 13, 14, Fig. 7 of the guide 10, or at parts where the guide is bent around a corner. The filter may also be used for preventing the passage of residual waves of one type after these have been nominally converted into waves of another type. For simultaneous working with two different types of waves, say Eo and Ho, one wave Eo is received at 15, Fig. 8, whilst the second wave Ho passes through the filter 10 and is received at 17. Waves of the Eo type from generator 23, Fig. 10, pass freely through the filter 21 and are transformed by a wave-converter 20 into waves of the Ho type, which then pass freely through the filter 22 which, however, stops waves of the Eo type. According to the Specification as open to inspection under Sect. 91, the distance between the two filter-elements may be varied to form an adjustable-impedance for matching different sections in transmission or reception. This subject-matter does not appear in the Specification as accepted.