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The case of a parabolic reflector and a point feed is considered, taking into account the question regarding the location in which the feed should be placed for an achievement of maximum directivity. Based on the tracing of geometrical rays, the obvious answer is obtained that the feed should be placed at the focal point. In the present paper, it is shown that this answer is not always correct. There are situations in which the maximum directivity is achieved when the feed is axially displaced toward the reflector or away from it. This 'focal shift' phenomenon is a result of three competing factors which affect the directivity of a reflector. The factors are related to phase synchronism over the reflector aperture, aperture illumination efficiency, and spillover loss. For achieving the maximum directivity, it is necessary to find the best compromise among the three factors.

A need for an accurate but inexpensive method for measuring and evaluating time delays of large ground antennas for VLBI applications motivated the development of the collimation tower technique. Supporting analytical work which was performed primarily to verify time delay measurement results obtained for a large antenna when the transmitter was at a collimation distance of 1/25 of the usual far field criterion is discussed. Comparisons of theoretical and experimental results are also given.

A need for an accurate but inexpensive method for measuring and evaluating time delays of large ground antennas for VLBI applications motivated the development of the collimation tower technique. Supporting analytical work which was performed primarily to verify time delay measurement results obtained for a large antenna when the transmitter was at a collimation distance of 1/25 of the usual far field criterion is discussed. Comparisons of theoretical and experimental results are also given.

A technique is presented in which the time an RF signal is delayed in propagating through a Cassegrain antenna is determined. The technique utilizes the group delay time and the envelope delay time as found from the antenna transfer function. The calculations show that a focused antenna is basically a nondispersive device whose delay time may be found from an optics formula. Small subreflector displacements result in significant delay changes requiring calibrations for many applications.

Applying method of moments to solution of integral equations for current induced on conducting cylinders in two-dimensional field

Computer program, 2DSCAT, solves integral equation for currents induced by electric or magnetic plane wave incident upon one or more conducting cylinders. Subroutine, FIELD, assumes that an incident wave is perpendicular to the cylindrical surface. Restrictions on this program are given.

Computer program solves integral equation for currents induced by electric or magnetic plane wave incident upon one or more conducting cylinders with a midplane of symmetry. Program utilizes symmetry of the geometry. Restrictions on the program are given.

Quasi-stationary coronal magnetic field and electron density from Faraday rotation experiment, using theoretical model

Beam switching Cassegrain antenna for millimeter wave radio astronomical measurements, describing RF and electronic systems

Monograph on analysis of reflector antennas covering electromagnetic field equations, computer aided design, etc

Phase center position of field scattered from hyperboloid subreflector in asymmetric Cassegrain antenna feed system

Transient Faraday rotation of S-band telemetry carrier observed during Pioneer 6 occultation by solar corona, correlating with decametric solar radio bursts

Pioneer 6 S band telemetry carrier Faraday rotation during corona occultation measured by deep space tracking antenna

Lunation study using millimeter wave radiometry for radio astronomy

Radiometric observations of moon during total lunar eclipse at 3.33 mm, noting decrease in equivalent black body disk temperature

Noise, gain, and antenna data for millimeter wave radiometers, and lunar eclipse observations

Digital computer technique for computing scattered pattern of complex hyperboloid subreflector in Cassegrain antenna feed systems

Edge diffraction from truncated parabolic and hyperbolic reflectors

Mechanical antenna beam switching device detects weak signals over atmospheric and equipment noise sources in microwave antennas. It periodically nutates the paraboloidal subdish in a Cassegrainian reflector system.

Atmospheric opacity and extraterrestrial radio source intensity related by improved Taylor series technique using least squares method

Computer program on far field scattering pattern of arbitrary spherical wave by arbitrary surface of revolution

Radiometric observations of total lunar eclipse of December 19, 1964 at wavelength of 3.3 mm indicate no significant temperature difference

Computer program to determine E and H plane phase centers of electromagnetic wave fields scattered from surfaces of revolution

Instrumentation and antenna development, solar observations, and lunation observations in study of millimeter wave radiometry for radio astronomy

Sky temperature measurements made at 90-Gc with radio telescope system consisting of 60-inch millimeter searchlight antenna and superheterodyne radiometer

Phase error and associated cross-polarization effects in Cassegrainian-fed microwave antenna

Millimeter wave radiometry for radio astronomy

Phase error and cross-polarization effects in Cassegrainian and microwave antennas

Integration of induced current distribution equations yields the scattered radiation field from a hyperboloidal reflector antenna in a cassegrainian feed system

Scattering from a hyperboloidal reflector

Radiation from a paraboloid with axial-dipole feed