Abstract: A dual-port IBOC® antenna provides omnidirectional radiation of orthogonal, circularly polarized analog (FM) and digital (OFDM) signals using quadruple coplanar square loops driven from a hybrid having balanced outputs. The loops are arranged in a tiled square, with proximal sides functioning as further stripline hybrids to cancel cross coupling between the loops. Each loop quad is reflector-backed and emits a directional signal; multiple loop quads oriented radially form an omni bay. Vertical spacing between bays includes a minimum position for mutual coupling, while symmetry establishes uniform input impedance on the hybrid input ports. Tuning barbs on the loops fine tune frequency response. Bandwidth is wide, so that a single antenna can radiate multiple FM analog and hybrid IBOC® channels over the VHF FM radio broadcast band.

Abstract: A center-pivoted, conductive vane equipped with contact-enhancing finger stock on the wiping edges rests during normal operation of a modified waveguide section parallel to and equidistant between the broad faces of the waveguide, where it interacts minimally with RF propagating through the waveguide. When it is desired to provide a short circuit to the waveguide, for a safety lockout or other uses, the vane can be rotated into a position to provide a substantial barrier to RF propagation. Rotating the pivot shaft, to which the vane is rigidly attached, performs rotation of the vane. The shaft is equipped with lockable stops for the open and shorted positions. Multiple center-pivoted vanes in a multiple-branch waveguide can form a switch.

Abstract: A center-pivoted, conductive vane equipped with contact-enhancing finger stock on the wiping edges rests during normal operation of a modified waveguide section parallel to and equidistant between the broad faces of the waveguide, where it interacts minimally with RF propagating through the waveguide. When it is desired to provide a short circuit to the waveguide, for a safety lockout or other uses, the vane can be rotated into a position to provide a substantial barrier to RF propagation. Rotating the pivot shaft, to which the vane is rigidly attached, performs rotation of the vane. The shaft is equipped with lockable stops for the open and shorted positions. Multiple center-pivoted vanes in a multiple-branch waveguide can form a switch.