Improvements in radio-directional aerial systems for very high frequency operation

摘要

572,470. Directional aerial systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and WRIGHT, F. M. July 7, 1941, No. 8584. [Class 40 (v)] In a directional aerial system for ultra-high frequency which includes a single-turn screened loop aerial and an associated omnidirectional aerial for determination of sense, a tuning condenser b for the loop aerial a and a leakage inductance gap e in the screen d are both symmetrically situated about the point of the loop aerial which, in operation, is at the highest potential, and the omnidirectional aerial f is symmetrically arranged in relation to the loop so as not to degrade the figure-of-eight diagram provided by it. In the form shown in Fig. 1, the aerial f is a rod in line with the vertical diameter of the loop, the lower end being connected to a tuned circuit g. Coupling between the two aerials is provided by a condenser plate h1 connected to the circuit g and adjustable in a tubular extension of the screening ' chamber i in relation to a fixed plate h11 constituted by or closely associated with a part of the loop aerial screen d. The screen i and the rotor of the series gap condenser b are connected by a conductor j extending along the vertical diameter of the loop to the equipotential point. The system is connected to the receiver by a screened coupling loop c. The conductor j may form a remote control for the rotor of the condenser b. The aerial f may be rendered inoperative, when figure-of-eight readings are to be made, by bringing the condenser plate h1 into contact with a flange m. In a modification, the length of the aerial f is adjustable and the condenser plate h1 is carried by a plunger adjusted by a cam operated through a rod from a handle at the base of the loop. In further modifications, the,open aerial f is off-set from the rotational axis of the loop in the plane containing the axis and perpendicular to the plane of the loop. Fig. 6 shows a preferred construction of this form, in which the tuned circuit of the open aerial is situated within the loop, and a further adjustable electrode z1 conneoted to the screen i operates as a capacity coupling to the loop aerial screening box n1 to balance the loop aerial during figures-of-eight observations. The aerial tuning condensers are ganged to a common control shaft j; on lowering this shaft against the action of a spring sp when a sense determination is to be made, the ganging clutch cl releases the condenser b to permit precise independent adjustment of the tuning of the open aerial f and at the same time opens a switch sw which during figure-ofeight readings short-circuits the tuning circuit of this aerial.