GB165038A - Improvements in electromagnetic wave signalling systems - Google Patents

Abstract

165,038. Mauborgne, J. O., and Hill, G. June 16, 1920, [Convention date]. Aerials; coupling oscillating and radiating circuits; directive signalling; multiplex signalling; transmitting systems and apparatus.-The transmitting-aerial consists of an ungrounded coil of closely-wound insulated wire, preferably formed on a core of insulating material, whereby the inductance, capacity, and resistance are uniformly distributed so that energy applied from any suitable source is radiated equally from each element of the coil. The wave-length emitted is determined by the electrical characteristics of the coil and by the location of the point P of applied potential. Or the energy may be applied at a fixed point, and the effective length of the coil adjusted until its natural wave-length corresponds with that of the source. If the point P is central, two equal waves are radiated; as it is moved towards one end of the coil, one shorter and one longer wave are emitted, until, when the point P is at the extremity of the coil, a single wave is again radiated having double the length of that given out when the point P is at the centre. Multiplex working may be effected in this manner Such an aerial is stated to have strongly directive properties, the direction of emission being perpendicular to the longitudinal axis of the coil. As shown in Fig. 3, high-frequency oscillations from a thermionic generator V are applied to the aerial A by a slider P which makes direct metallic contact therewith. No earth lead is necessary. A spark-gap or are source may be similarly connected. As shown in Fig. 6, a tuned circuit C1, R across a spark-gap S is inductively coupled to the coil-aerial. The electromagnetic coupling R can be adjusted to any point along the aerial. Alternatively, the coupling with the aerial may be electrostatic. Fig. 8 shows an arrangement in which two coil-aerials are separately excited one from each side of a spark-gap S; or both coils may be connected to one side of the source S. The use of several such aerials in parallel provides an efficient means of transmission with considerable power on very short wave-lengths. In the arrangement shown in Fig. 10, an earth lead G is employed, which under certain conditions is stated to give an increased efficiency at the expense of some loss in the directional effects. In Fig. 11, the second slider Q may be connected to a radiating antenna, or to a distant receiving station for wired-wireless work; or it may be earthed. Curved or arc-shaped aerials, wound upon a flexible rubber core, may be used if it is desired to radiate energy in various directions simultaneously. The high-frequency oscillations applied to the coil-aerial may be modulated for speech transmission.