Directional antenna system with end loaded crossed dipoles

Abstract

An electrically directable antenna system is provided which is tunable to individual stations in the FM band. The antenna system includes a pair of crossed, forshortened dipole components which are arranged to be mutually perpendicular. Each of the dipole components includes a pair of longitudinally aligned arms which are flared at their outer ends so as to be shaped generally like an arrow. At their inner ends, these arms are connected to a narrow bandwidth tuner network which is designed to resonate the dipole components at a frequency corresponding to a selected station and to impedance match each of the dipole components to the input of the FM receiver. The tuner network includes a bandwidth control, which is operable to produce a predetermined impedance mismatch between the dipole components and the receiver input so that, without changing the frequency to which the antenna system is tuned, the overall antenna system gain can be made substantially constant over the entire FM band. The signals from the four dipole arms, as coupled through the tuner network, are selectively combined in a direction selector switch so that the signal provided from the switch to the receiver input is either: one of the dipole component signals, the sum of the two dipole component signals, or the difference between the two dipole component signals. The particular signal applied to the receiver determines the directionality of the antenna system.