GB362530A - Improvements in and relating to wireless telegraphy and telephony - Google Patents

Abstract

362,530. Directive wireless signalling. MACKENZIE, W. B., RAWLINSON, W. F., and BORROW, R. L. A., H.M. Signal School, Royal Naval Barracks, Portsmouth. Sept. 10, 1930, No. 27091. [Class 40 (v).] Two normallydirective aerials, such as a ship's installation of two crossed frames, can be made, if necessary, non-directional by combining the output from the two frames in a common circuit through separate coupling-channels in which a phase difference of 90‹ is introduced. As shown in Fig. 1 the aerial circuit A, C1, E is tuned to a frequency slightly higher, and the aerial circuit B, D1, F to one slightly lower, than the signal frequency to which the common circuit G, C is tuned. The 90‹ phase difference is obtained by relative adjustment of the condensers C1, D1. Equal amplitude is secured through the couplings E, F. The current in the circuit G, C is independent of the direction of incidence of the wave. Fig. 2 shows an alternative arrangement in which the voltage between the points M, N is 90‹ out of phase with the voltage across the points N, P owing to the relative disposition of the resistance-capacity coupling elements R1 C3, R2, C4. The combined currents are applied to the grid of the amplifier V5. Alternatively, as shown in Fig. 4, the necessary 90‹ phase difference is imparted by means of a local heterodyne oscillator O, the output from which is fed to two valves V3, V4. The anode circuit of V3 comprises an inductance M, and the output is coupled at K both to the aerial A and input circuit G, C; whilst the anode circuit of V4 comprises a resistance N and is coupled at L to the aerial B and input circuit H, D. The combined non- directional input is fed to a common amplifier V5. In a modified arrangement the 90‹ phase difference is introduced in the intermediate-frequency stage of a superheterodyne receiver.