Abstract: An electromagnetic filter assembly includes complimentary first and second blocks (1) and (2) defining two conjoined sections (10), (11) of an electromagnetic waveguide duct. A shim-like electromagnetic filter element (3) is held between the blocks and contains a series of holes (14) defining bridges (15) which traverse the waveguide duct to form poles of an electromagnetic filter. The filter element includes integral tuning projections (20) which extend into waveguide duct between the bridges. By adjusting the position of the filter element (3) between the blocks (1), (2) it is possible to vary the extent to which the tuning projections (20) project into the waveguide duct. The arrangement thus facilitates the repeated, continuous adjustment and variation of the electrical characteristics of devices such as filters, diplexers and multiplexers.

Abstract: An electromagnetic filter assembly includes complimentary first and second blocks (1) and (2) defining two conjoined sections (10), (11) of an electromagnetic waveguide duct. A shim-like electromagnetic filter element (3) is held between the blocks and contains a series of holes (14) defining bridges (15) which traverse the waveguide duct to form poles of an electromagnetic filter. The filter element includes integral tuning projections (20) which extend into waveguide duct between the bridges. By adjusting the position of the filter element (3) between the blocks (1), (2) it is possible to vary the extent to which the tuning projections (20) project into the waveguide duct. The arrangement thus facilitates the repeated, continuous adjustment and variation of the electrical characteristics of devices such is filters, diplexers and multiplexers.

Abstract: A dual polarized flat plate antenna structure has a single circular waveguide output accommodating probes for separate orthogonally polarized signals. A housing to be affixed to the antenna structure contains a low noise block having a single circular waveguide input with complementary probes. The housing is rotatable relative to the antenna structure about the common axis of the waveguides. The low noise block incorporates switching means for selectively coupling the output signals of the antenna array structure with a common low noise block input circuit. Rotation of the low noise block enables the angle of the polarizing coupling between the array output probes and the low noise block input probes to be varied.