Abstract: A frequency independent constant beamwidth lens antenna concept is descri utilizing a point source to point focus nonspherical lens. The essential feature is that a twisted planar or hyperbolic paraboloidal phase or wave front is formed by the antenna which then in turn produces a frequency indepenent constant beamwidth beam in the far field of the antenna for radiation or reception of planar or nearly planar spherical waves. Moreover, the frequency independent constant beamwidth beam may be steered or scanned in azimuth without moving the lens antenna or a plurality of fixed beams in different directions may be formed simultaneously by the lens antenna.

Abstract: A frequency independent constant beamwidth lens antenna concept is descri. The device may be configured in various ways such as with a cylindrical lens with a retina. The essential feature is that a twisted planar or hyperbolic paraboloidal phase or wave front is formed by the antenna which then in turn produces a frequency independent constant beamwidth beam in the far field of the antenna. Moreover, the frequency independent constant beamwidth beam may be steered or scanned in azimuth without moving the lens.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: A frequency independent log periodic acoustic device is utilized for the transmission or reception of underwater sound. A key element of the device is a particularly shaped plate or diaphragm, called a filter plate, made of stainless steel or other material having suitable acoustic properties. The filter plate on being placed in front of any plane wave receiving or transmitting transducer acts automatically to make the beamwidth of the diffraction pattern of the combined device constant, regardless of frequency. This is achieved by automatically making the effective aperture diameter of the filter plate-transducer combination a constant multiple of the acoustic wavelength of the sound in the underwater medium. When used in conjunction with a scannable transducer such as an acoustic lens and the retina device the filter plate produces a directional, scannable, substantially constant beamwidth diffraction pattern for radiation or reception of underwater acoustic signals.

Abstract: A frequency independent log periodic acoustic device is utilized for the transmission or reception of underwater sound. The acoustic device when used in conjunction with any substantially plane wave receiving or transmitting transducer produces a directional, substantially constant beamwidth diffraction pattern for radiation or reception of underwater sound signals. A key element of the device is a particularly shaped plate or diaphragm, called a filter plate, made of stainless steel or other material having suitable acoustic properties. The filter plate on being placed in front of any plane wave receiving or transmitting transducer acts automatically to make the beamwidth of the diffraction pattern of the combined device constant, regardless of frequency. This is achieved by automatically making the effective aperture diameter of the filter plate-transducer combination a constant multiple of the acoustic wavelength of the sound in the underwater medium.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: A wide band, substantially constant beamwidth, frequency independent, scable acoustic array uses a mosaic pattern acoustic lens arrangement of fully directive acoustic lens antennas as the primary array antenna elements. The lenses at the center of the array pass signals at all frequencies, the lenses near but not at the center pass all signals except those at the highest frequencies and the lenses on the outer periphery pass only those signals at the lowest frequencies. When used as a transmitter, a wide band source supplies a broad band frequency signal to a plurality of filters, time delays, amplifiers, switches and acoustic retinas for applying predetermined signals to the acoustic lenses. When used as a receiver the same plurality of filters, time delays, amplifiers, switches and acoustic retinas act in a complimentary reciprocal fashion in the recovery of signals.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical infrared lens of very low or even minimal F-number providing balanced astigmatism for wide angle infrared applications is described. The infrared lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the lens at infinity; i.e., the infrared lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave beams directed towards infinity at equal but opposite angles with respect to the infrared lens axis. The infrared lens may be built of various materials such as vitreous quartz.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical optical lens of very low or even minimal F-number providing balanced astigmatism for wide angle optical applications is described. The optical lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the lens at infinity; i.e., the optical lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave beams directed towards infinity at equal but opposite angles with respect to the optical lens axis. The optical lens may be built of various materials such as any of several barium flint glasses.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustic, microwave or optical applications is described. The lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave beams directed towards infinity at equal but opposite angles with respect to the lens axis. The lens may be built of various materials depending on its intended application in acoustics, microwaves or optics.

Abstract: A single acoustic filter plate-lens unit for providing directional, frequy independent beam-forming. The unit comprises a liquid container having a curved and radially tapered stainless steel plate on one side and thin metallic shell on the other. An acoustically slow liquid fills the space between the plates. The unit can be used in conjunction with a retina transducer system for conversion of acoustic signals into electrical signals and vice versa.