GB1236529A - Improvements in or relating to antenna systems - Google Patents

Abstract

1,236,529. Aerials; duplex radio signalling. ALBISWERK ZURICH A.G. 2 Sept., 1969 [25 Sept., 1968], No. 43369/69. Headings H4A and H4L. An aerial system for the simultaneous transmission and reception of two waves which are orthogonally polarized and which differ in frequency by an amount equivalent to a desired intermediate frequency, comprises a primary horn radiator 1, Fig. 1, which faces a reflector 11, and which is supported by stays 12, 13, 14, 15 from said reflector. Coaxial feeders 16, 17 from the rear of the reflector 11 extend along the stays 12, 13 into the horn 1. Said horn comprises a rectangular cross-section waveguide portion, which is terminated by a shortcircuiting plate 4, Fig. 2, at the rear, and which is flared out to a rectangular aperture in front. A transmitting probe 2 extends from the feeder 17 into the horn, near the aperture. It is disposed parallel to one pair of sides of the rectangular horn, and is fitted with a rod 23 of dielectric material to improve matching. A receiving probe 3 is constituted by a semiconductor diode which is disposed parallel to the other pair of sides of the rectangular horn and near the short-circuiting plate 4. The crosssection of the rectangular horn in the region of the short-circuiting plate may be such as to support the fundamental mode of the received waves, and the long side of the rectangular aperture of the horn may be parallel to the electric field of said waves. The casing of the diode of the probe 3 is secured to one wall of the rectangular cross-section waveguide portion of the horn, and a pin from its other side extends into a coaxial plug 26, for the feeder 16. To improve matching, the probe 3 is displaced away from the centre-line of the said rectangular cross-section, and a choke coupling 27 is provided for the plug 26. The probe 3 picks up a small portion of the energy transmitted by the probe 2, although it is orthogonally polarized, and this is heterodyned with received energy in the diode to produce an output at the intermediate frequency on the feeder 16. In another embodiment, a receiving probe (30), Fig. 3 (not shown), extends into the horn near the shortcircuiting plate from an associated semiconductor diode (31) outside the waveguide portion of the horn. A dielectric material rod (32) is fitted to the probe (30), to improve matching.