Showing papers on "Smart antenna published in 1975"

Interferometric doppler guidance system

Abstract: A means for identifying a particular range and Doppler shift signal in the field of view of a moving radar antenna which determines azimuth angle to this range-Doppler signal relative to the antenna by determining the phase difference between said signal as processed through two channels each fed by antennas displaced in a horizontal direction with respect to the axis of the antenna system.

Passive direction finding system

Abstract: A passive direction finding system incorporating at least one set of spacapart antennas, the incoming signal at one antenna being coupled through a delay line having a multiplicity of taps thereon, a plurality of channels equal in number to the number of delay taps and signal processing means coupled to the output of said channels, a reference channel coupled to the output of the other antenna, phase shifting means for varying the phase of the reference channel signal, a frequency modulated oscillator which provides an output signal that is beat against the outputs of the delay line and the output of the second antenna, and a correlator coupled to the output of the channels for determining when correlation exists between a signal from the first antenna and the second antenna to indicate direction of an incoming signal with respect to the baseline between the set of antennas.

Mobile antenna gain at 900 MHz

Abstract: A program has been initiated to investigate the effect of the urban multipath environment on mobile antennas at 900 MHz. The program involves the constructuion of several mobile antennas, careful measurement of these antennas on an antenna range to determine their characteristics in a controlled environment, then measurement of their characteristics in the multipath environment of cities. Measured results are compared to computed results to permit generalized conclusions to be reached. This paper presents the results of the first phase of the program; measurements made in the controlled pattern range environment.

A Modified Monopulse Technique for Radar Tracking with Low-Angle Multipath

Abstract: In this paper a new monopluse technique for reducing radar multipath angle-tracking errors is proposed. The solution is achieved by using two monopulse antennas at different heights. The available signals allow one to control the antenna-height diversity so that the elevation angle control signal is not affected by reflected-wave components. The size of the antenna system may be reduced by properly using phase shifters. A possible configuration of such a system is considered and some practical data on the antenna-height diversity are discussed.

The Effect of Rotating Antennas and Signal Polarization on Doppler Shift

Abstract: A study is made of a transmitting antenna spinning relative to a receiving antenna, showing that the received signal undergoes a phase shift which depends upon the relative orientation and the ellipticity conditions of the two antennas. It is shown that this phase shift is important in Doppler distance measuring equipment because it must not be confused with the phase shift caused by the changing distance between the antennas.

Design of optimal line-source antennas

Abstract: The design of optimal antenna patterns subject to sidelobe constraints is considered. A function space formulation of the antenna pattern shaping problem yields several advantages over currently available techniques for computing optimal line-source excitations. The two basic problems studied are a) maximizing directivity subject to hard, possibly angle-dependent, constraints on the sidelobe level and beamwidth; and b) antenna pattern shaping where the approximating pattern must fit into a known envelope.

The effect of tolerances on the isolation of frequency reuse antennas

Abstract: The expression for the expected isolation between two orthogonally polarized signals of a single beam frequency reuse array antenna when excitation, position, and orientation of the elements are subjected to independent random variables is derived. The isolation loss and the fundamental limitation of a multibeam frequency reuse antenna system are discussed.

Mobile antenna gain at 900 MHz

Abstract: A program has been initiated to investigate the effect of the Urban multipath environment on mobile antennas at 900 MHz. The program involves the construction of several mobile antennas, careful measurement of these antennas on an antenna range to determine their characteristics in a controlled environment, then measurement of their characteristics in the multipath environment of cities. Measured results are compared to computed results to permit generalized conclusions to be reached. This paper presents the results of the first phase of the program; measurements made in the controlled pattern range environment.