Patent GB-138588-A (GB)
Title: Improvements in radio signalling apparatus
IPC: H04B1/12
Filed: 1919-08-06
Abstract: 138,588. Marconi Wireless Telegraph Co., (Assignees of Weagant, R. A.). Feb. 7, 1919, [Convention date]. Wireless signalling; aerials. - Relates to methods of minimizing static interference in the reception of wireless signals based on the theory that static signals arise from vertically-propagated waves polarized in various directions, and consists in employing a vertical non-directive aerial and one or more directive aerials and in connecting them to a single detector or goniometer so that the current due to statics is balanced out whilst that due to the desired signals is effective. The non-directive aerial may be structurally combined with the directive aerials, the structure as a whole acting as a vertical receiving aerial. As shown in Fig. 1, the vertical aerial A having a counterpoise earth D is coupled to a secondary circuit J having the detector connected across its condenser. The directive aerial comprises two or more vertical loops F, G connected in series and coupled to the coil L of the secondary circuit. The directive aerial circuit comprises adjustable inductances 0 and an adjustable condenser N placed between the two halves of the coupling M. A switch H enables one loop F to be reversed with respect to the other loop G. The best position of the reversing switch for balancing out statics is found by trial; or one of the loop aerials F, G is turned about a vertical axis until the proper position is found. The best reception of signals is effected from the direction P or direction Q according to the position of the reversing switch H In a modified arrangement, the vertical aerial A is coupled to a circuit including one fixed coil of a radiogoniometer, the other fixed coil being connected through a reversing-switch to the loop aerials. The circuit of the movable coil is coupled to the detector circuit. In another modification, shown in Fig. 3, the loop aerials are replaced by horizontal crossed aerials W, X including variable condensers Z and inductance coils Y. The aerials W, X are coupled to circuits W<1>, X' which are connected in series or opposition by a switch H'. The circuit W', X<1> is coupled at Z' to one fixed coil R of a goniometer, the other fixed coil R being coupled to the vertical aerial A. The movable coil S in coupled to the detector circuit J'. Variable condensers U are preferably in circuit with the goniometer coils. In the arrangement shown in Fig. 4, the loop aerials F, G form part of the vertical oscillator. In so far as the aerials F, G operate as loop aerials their effect is transmitted to the detector circuit J through the coupling L, M. The connecting-point A<2> of the vertical aerial portion A' to the coil M is so chosen that currents due to the aerials receiving as a vertical oscillator do not affect the coil L, these currents acting on the detector circuit through the coupling C, K. Fig. 6 shows a similar arrangement in which horizontal crossed aerials W, X are utilized as a vertical oscillator. The horizontal aerials are coupled to the detector circuit J', which is also coupled to the vertical lead A<1> connecting the counterpoise D to suitably-chosen points A<2> on the coupling coils Y of the aerials W, X. A single horizontal aerial may be employed with a vertical aerial projecting upwards or downwards from a mid-point of the central inductance coil. The vertical and horizontal aerials are coupled respectively to circuits containing the fixed coils of a goniometer, the movable coil of which is connected to the detector circuit.