GB628916A - Improvements relating to radio antennae coupling arrangements - Google Patents

Abstract

628,916. Aerial coupling arrangements. COSSOR, Ltd., A. C., and BELL, D. A. June 24, 1946, No. 18928. [Class 40 (v)] The invention relates to the coupling arrangement used between an antenna and its associated radio apparatus, whereby the antenna may be used for the reception of different frequency bands such as those of television and the normal broadcast frequencies. For television frequencies, the aerial is matched with and directly coupled to the feeder, and for normal broadcast frequencies, the upper limb of the dipole aerial or another rod is used as a rod aerial which is coupled to the feeder through a cathode follower valve. In Fig. I, the upper limb UL of a dipole aerial is connected through a series acceptor circuit CH1, C1 to lead 2 of the feeder cable, and the lower limb LL is directly coupled to lead 1 ; this constitutes direct coupling between aerial and feeder for television frequencies, the output being applied through transformer T to a television receiver. In order to receive the lower broadcast frequencies, the upper limb UL functions as a rod aerial and is connected through cathode follower valve V to lead 1 of the feeder, so that the aerial and feeder impedances may be matched at these frequencies. The output between lead 1 and the conducting screen CA is applied to a multiband broadcast receiver BR. The filament supply of valve V is supplied through the screen conductor CA and lead 1 of the cable, and the H.T. supply through the screen and lead 2. The whole mast-head circuit is surrounded by an earthed casing B. A modification is described in which a coaxial cable is used in place of the screened twinfeeder. In this case the inner conductor is used to supply the H.T. voltage, and an auxiliary lead is used for the positive filament supply.