GB1415994A - Antenna apparatus - Google Patents

Abstract

1415994 Aerials SPERRY RAND CORP 9 April 1974 [7 May 1973] 15565/74 Heading H4A Aerial apparatus comprises dielectric material E/M wave collimating means 3 having a substantially cylindrical or spherical boundary, E/M wave distributor means 1 having an. energy-exchanging aperture movable along a substantially part-cylindrical or part-spherical boundary, and multiple transmission line means 2 extending in energy exchanging; relation between portions of said two boundaries. In a first embodiment, shown in Fig. 1, the means 3 is a right circular cylinder of low-loss dielectric material, and may be a Luneberg type lens. The means 1 comprises a pyramidal horn 4, which is fed by a waveguide 8, and which is rotatable about a axis 10 along an arc 5. The means 2 comprises a one-dimensional stack of rectangular waveguides which extend from. the arc 5 to the boundary 26 of the lens 3. The waveguides are symmetrically arranged in. pairs (16, 16); (17, 17), ... (22, 22) about a median plane 15, which passes through the centre 42 of the lens 3 and through the axis 10. Impedance matching elements are provided at the ends of the waveguides, e.g. the elements 24, 25 at the ends of the waveguides 22. Said elements may be blocks of dielectric material. Delay means 36 to 41 are provided within the waveguides 16 to 21 in order to make the E/M wave propagation times through all waveguides substantially equal. Said delay means may be made of dielectric material of graded lengths and dielectric constants. The beam from the aerial may be scanned in the plane perpendicular to the plane 15 by rotation of the horn 4 about the axis 10. As shown, with the horn 4 at the L.H. extremity of the arc 5, a beam 31 is emitted which is directed to the right of the plane 15. When the horn is at a position 7 at the R.H. extremity of the arc 5, a beam 33 is emitted which is directed to the left of the plane 15. In a second embodiment, shown in Fig. 2, the means 3 is a spherical lens, the horn 4 of the means 4 is gimbal-mounted so that it may be rotated about two orthogonal axes 10, 45, and the means 2 comprises a two-dimensional stack of waveguides, with part-spherical end surfaces cooperating respectively with the lens 3 and with the horn 4. Instead of rectangular waveguides hexagonal waveguides may be used (Fig. 3, not shown). Methods of making Luneberg lenses are mentioned. In these lenses, where, n = effective index of refraction, and r = normalized distance from the centre. Cylinders are formed by winding up thin ribbons of low-loss dielectric material containing metallic particles in controlled densities. Pyramidal sectors made from such cylinders may be stacked to form spheres.