Abstract: The antenna includes four elements excited with equal amplitudes but with a relative phase difference of 0°, ?90°, ?180°, and ?270°. Each element includes a vertical and horizontal portion. An RF trap filter is located within the horizontal portion so that the antenna provides good gain coverage at all three frequency bands of a modernized global positioning system.

Abstract: The antenna includes four elements excited with equal amplitudes but with a relative phase difference of 0°, −90°, −180°, and −270°. Each element includes a vertical and horizontal portion. An RF trap filter is located within the horizontal portion so that the antenna provides good gain coverage at all three frequency bands of a modernized global positioning system.

Abstract: An apparatus and method for measuring the height of a liquid above a reference level in which short pulses of subnanosecond duration are coupled to a dual-mode transmission line immersed in a liquid to propagate thereon in a plurality of modes. A surface wave propagating on the outer conductor is reflected from the surface of the liquid, and coaxial-mode propagating within the transmission line is reflected from the reference level. These reflected pulses propagate back along the transmission line, coupled to a receiver for detection, the detected pulses processed to determine the liquid height above a reference level.

Abstract: A dome antenna with cross polarization compensation for reducing cross polarization induced monopulse tracking errors controls the polarization at the elements of the feed array to reduce the cross-polarization component in a far field radiation pattern of the antenna. Cross-polarization components at each element in the feed array for a linearly polarized plane wave incident at a predetermined direction to the dome are determined and each element is oriented to be polarized orthogonally to the cross-polarized component at that element.