Abstract: An electromagnetic bandgap device is mountable on a RF disturbing structure of an antenna to minimize signal field disturbance imparted thereby. The RF disturbing structure is oriented in a direction substantially parallel to a path of travel of an antenna signal and located within a field covered by the signal transmitted by a feed. The bandgap device comprises a plurality of RF perturbing elements connected to the RF disturbing structure and spaced apart from one another in the direction substantially parallel to the signal path. The perturbing elements are positioned, configured and sized to direct a disturbed portion of the signal away therefrom to reduce field disturbance generated by the disturbed signal portion interacting with an undisturbed portion of the antenna signal.

Abstract: A multimode horn used to feed an antenna includes a generally tapered wall for transmitting and/or receiving an electromagnetic signal there through. The wall flares radially outwardly from a throat section to an aperture and defines an internal surface having a plurality of discontinuities. The geometry of the discontinuities are configured and sized to alter the dominant mode, which conveys the communications signal, into a higher order symmetrical mode content to achieve a balance between a plurality of communications performance parameters of the antenna over a pre-determined frequency range of the signal. The discontinuities are also designed to match the horn impedance for the modes of the communications signal and for an asymmetrical mode content of a simultaneously propagating tracking signal.

Abstract: An electromagnetic bandgap device is mountable on a RF disturbing structure of an antenna to minimize signal field disturbance imparted thereby. The RF disturbing structure is oriented in a direction substantially parallel to a path of travel of an antenna signal and located within a field covered by the signal transmitted by a feed. The bandgap device comprises a plurality of RF perturbing elements connected to the RF disturbing structure and spaced apart from one another in the direction substantially parallel to the signal path. The perturbing elements are positioned, configured and sized to direct a disturbed portion of the signal away therefrom to reduce field disturbance generated by the disturbed signal portion interacting with an undisturbed portion of the antenna signal.