The performance of a balanced aerial when connected directly to a coaxial cable

Measurements have been made of the radiation patterns of typical aerials, such as would be used for domestic reception in the v.h.f. band, connected directly to a coaxial cable without the intervention of a balance/unbalance transformer. The vertical radiation pattern may be appreciably distorted, owing to the excitation of currents on the outside of the cable and the sensitivity to vertically-polarized interference originating near to and below the aerial may be increased. The distortion of the radiation pattern appears to be less serious with directional aerials. The use of a balance/unbalance transformer or a balanced feeder would be desirable, but unless the input circuit of the receiver is either balanced, or screened and unbalanced, no ideal solution exists.