Patent GB-683353-A (GB)
Title: Transmission line system for microwave signals
IPC: H04B3/54
Filed: 1951-01-12
Abstract: 683,353. Micro-wave line signaling. STANDARD TELEPHONES & CABLES, Ltd. Jan. 12, 1951 [March 27, 1950], No. 955/51. Class 40 (v). [Also in Group XL (b)] A conductor used for some other purpose, such as a power line, is also used for micro-wave signalling by providing an insulating coating on the conductor, the micro-waves being guided by the conductor and transmitted as surface waves confined substantially within a limited radius about the conductor. The invention includes directional junctions at points where the microwave signalling apparatus joins the power line, or where the micro-wave line forks; high-pass and low-pass filters for separating micro-waves of different frequencies employed for signals proceeding in different directions along the line, and for excluding power currents from the signalling appartus; and a two-way repeater for amplifying the micro-waves. Fig. 1 shows the general arrangement, Fig. 3, a junction between a micro-wave line and a power line, and Fig. 9 a high-pass filter. In Fig. 1, the signal transmitter 5 and receiver 6 at one terminal point are connected respectively through low-pass filter 7 and highpass filter 8 to a junction 11 which is connected through a power separator 13 to a junction 15 with a line 2 of a power transmission system. At an intermediate point on the line, a microwave repeater 18 is located and at a further intermediate point 19 signal-receiving and transmitting equipment is provided. Multiple transmission may be effected by the use of different micro-wave frequencies or by other means. Repeater. At intermediate points along the line, the micro-wave signals are led off to repeater 18, Fig. 1. East-bound signals are fed through a power separator 20 to an amplifier 30 preferably of the travelling-wave type, and the amplified output proceeds through a L.P. filter 32 and power separator 21 to rejoin the power line 2. West-bound micro-waves, which are of higher frequency, proceed through the amplifier 30 and filter 31. Intermediate signalling stations.-East-bound signals from the terminal station proceed through power separator 33 and if of the frequency receivable at the intermediate station, they pass through L.P. filters 43, 46 to the receiver 6A. Signals initiated at 5A pass through H.P. filters 45, 41 for transmission to the terminal station. Signals not required to be diverted to the intermediate station pass from one power separator 33 or 34 through a high-pass filter 42 to the other power separator 34 or 33 and thence back to the power line. The Specification also describes a modified arrangement of the filters at an intermediate station, Fig. 10 (not shown). Filters.-A high-pass filter, Fig. 9, comprises a wave-guide 59, preferably of cylindrical form, with axial micro-wave conductors 61, 62 entering at each end, the insulation being increased in thickness until it fills the guide. Only micro-waves of sufficiently high frequency to pass through the guide are transferred from one conductor to the other. Power currents are therefore stopped by the filter, and insulation may be provided by a high-voltage ribbed insulator 63 attached to one end of the guide. Low-pass filters may comprise an axial rod attached to the micro-wave conductors at each end and fitted with spaced conducting discs, as described in Specification 683,352, [Group XL (b)], Fig. 8 (not shown). Junctions.-When a micro-wave conductor 14A, Fig. 3, joins a power line 2, as at 15, Fig. 1, the conductor 14A curves gradually into the power line, and the insulation is thinned down at 47 in the angle between the lines, and is thickened on the opposite side at 48. At a forked junction between two micro-wave conductors, Figs. 5 and 6 (not shown), the insulation is similarly thinned within the fork and thickened on the outer side.