GB1247629A - Improvements in and relating to dipole antenna arrangements - Google Patents

Abstract

1,247,629. Aerials. LICENTIA PATENTVERWALTUNGS G.m.b.H. 13 April, 1970 [7 May, 1969], No. 17425/70. Heading H4A. In a multiple dipole aerial arrangement, a plurality of transmitter/receiver units operable in a specified R.F. range are connected by individual feeders 4, 5, 6 to respective dipoles 1, 1; 2, 2; 3, 3, which are mounted on a mast colinearly above one another, and are insulated from one another. Decoupling means for the dipoles includes inductances inserted in the feeders near the lower ends and feed points of the dipoles, which form with stray capacitances parallel circuits resonant at pre-determined frequencies within the specified R.F. range. As described, the dipole members are circular or polygonal cross-section bars or tubes, the feeders are co-axial cables the impedances of which approximately match those of the dipoles, and the inductances are constituted by coiling the cables, as at 8, 9. With parallel wire feeders, the inductances are in the form of bifilar coils. Alternatively, the inductances may be in the form of wound ferrite cores. The mast may be a synthetic materials rod or tube upon which tubular dipole members are threaded and are then secured. With a tubular mast, the feeders may be run inside, and the inductances may be embedded by a casting process. The arrangement is particularly for mobile installations, such as vehicles and craft.