GB592126A - Improvements in or relating to high frequency electrical transmission lines - Google Patents

Abstract

592,126. Aerial feeding arrangements; aerials ; impedance networks. GARFITT, R. G. April 30, 1945, No. 10931. [Classes 40 (iii) and 40 (v)] The outer conductor of an unbalanced coaxial line feeding a balanced system such as a centrefed dipole is divided so as to provide two terminals by slots parallel to the inner conductor and at least a quarter of a wavelength long, the inner conductor being connected to a point on one of the terminal portions. The outer conductor 11 of a coaxial feeder, Fig. 1, is divided by two diametrically opposed slots 13 of length #/4 to form two terminal portions 14, 15. The inner conductor 12 is connected to one portion 15 by a bridging piece 16. The mid-points of the opposite portions 14, 15 serve as terminals to connect the elements of a dipole 19, or a balanced line. The bridging piece 16 may be moved down the portion 15. The termination may be screened by a can 20, concentric with the line and connected to the outer conductor 11 below the slots 13. The dipole elements 19 pass through holes or slots 22. In a modification, Fig. 4, dipole elements are connected to terminal portions of the outer conductor 11b formed by slots 13b of length #/2 at a distance #/4 from the bottom of the slots, the inner conductor 12b being connected to one of the portions at the same point. The free ends of the portions are short-circuited by a bridging piece 31, and form a support for a parasitic reflector 32 co-operating with the dipole 33. The interior of the coaxial line may be filled with a moulding of plastic material which is arranged to enclose the. terminating arrangements (Fig. 3, not shown), the dipole elements and a probe which connects the inner conductor of the coaxial line with the interior of a wave-guide.