GB1179768A - Improvements in or relating to Aerial Arrangements of the Radiating Aperture Type - Google Patents

Abstract

1,179,768. Aerials. TELEFUNKEN PATENTVERWERTUNGS-G.m.b.H. 28 Feb., 1967 [9 March, 1966], No. 9552/67. Heading H4A. In an aerial arrangement comprising a multimode waveguide leading at one end to a radiating aperture, which may be in a radio horn, and fed at the other end by a plurality of monomode waveguides, the relative amplitudes of the various modes developed in the multimode waveguide, and hence the energy distribution pattern across the radiating aperture, are made to conform to predetermined values by suitably spacing apart the feeder waveguides, which are supplied at predetermined amplitudes, and either in phase or in anti-phase. In a first embodiment, two parallel rectangular waveguides 4, 5, Fig. 2, each of crosssectional dimensions a x b feed into one end of a third parallel waveguide 3, of cross-sectional dimensions a<SP>1</SP> Î b and length c. At the frequency of operation the waveguides 4, 5 can support only the H 10 mode, but the waveguide 3 can support higher modes in addition to the H 10 mode. If the waveguides 4, 5 are supplied in phase, at equal amplitudes, the H 10 and H 30 modes are developed in the waveguide 3. The desired relative magnitudes of the H 10 and H 30 modes are obtained by suitably choosing the spacing apart of the waveguides 4, 5 in the H-plane. It is also possible to develop the H 40 mode in the waveguide 3 and, by supplying the waveguides 4, 5 in anti-phase, the H 20 mode. In a second embodiment, three waveguides similar to the waveguides 4, 5, Fig. 2, feed a suitably dimensioned multimode waveguide in which the H 50 mode is thereby developed. In a third embodiment, two feeder waveguides 6, 7, Fig. 6, are spaced apart in the E- plane and excite a multimode waveguide 8. The waveguides 6, 7 allow only the H 10 mode to be transmitted, but in the waveguide 8 the H 10 ,H 11 ,E 11 , H 12 and E 12 modes can exist. In a fourth embodiment, a third feeder waveguide is provided between two feeder waveguides such as 6, 7, Fig. 6, so that higher modes can be developed in a suitably dimensioned multimode waveguide, and a fifth embodiment (Fig. 10) consists of a combination of the first and third embodiments (Figs. 2 and 6). The arrangements are stated to be particularly applicable to monopulse operation and by means of coupling devices sum and difference patterns may be developed with low side-lobe effects. Reference has been directed by the Comptroller to Specification 1,002,140.