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This paper presents the results of our investigation of code positioning techniques using execution profile data as input into the compilation process. The primary objective of the positioning is to reduce the overhead of the instruction memory hierarchy. After initial investigation in the literature, we decided to implement two prototypes for the(More)
The effects of focused aperture amplitude tapering, both direct and inverse, on axial forelobes and aftlobes are investigated. Taylor tapers give low sidelobes but high forelobes and aftlobes, plus a modest gain degradation. Inverse tapers give low forelobes and aftlobes but high sidelobes and large gain degradation. Uniform excitation gives comparable(More)
A finite-by-infinite array of thin half-wave dipoles with H-plane scan is used to show the existence of a Gibbs' phenomenon-type standing wave in scan impedance (normalized by the infinite array value) over the elements of the array. The period of this wave is .SA at broadside for X/2 array spacing and increases as the scan angle increases by a grating(More)
—The regular oscillations in scan impedance (normalized by the infinite array values) that occur across a finite array are uniquely altered in two special cases based on computer simulations of finite-by-infinite arrays. First, dipoles with groundplane at broadside in the E E E-plane, exhibit a slow modulation of the usual oscillations; the period of the(More)
The Chu fundamental limitation on Q for electrically small antennas is well known and widely used. However, Chu did not include energy stored inside the hypothetical enveloping sphere. Exact calculation of total stored energy by Thai gives a new Q, which should better match well-designed electrically small antennas. The TM-and TE-mode Q formulas are(More)
Antenna array distributions and their associated patterns are now designed on physical principles, based on placement of zeros of the array polynomial. An overview of the synthesis processes is given. Robust and low Q distributions for linear arrays and circular planar arrays, that provide variable side lobe level pencil beam patterns, are treated in(More)
—Exact vector potential integrals are written in spherical coordinates for the CWTHA. From these the far fields are expressed, both for the CWTHA (dipole field) and for a single winding (loop field). The vector potentials are numerically integrated; the results give the dipole field for a given current and ratio of dipole field to loop field.
The transient build-up and decay of the radiated field produced by a short pulse in a reflector antenna are examined. The transient time is proportional to diameter, and inversely proportional to f/D, thus Cassegrain reflectors have better short-pulse response. With the steady progress in ability to generate RF power in shorter pulses and to build larger(More)
—The concept of connected (or coupled) dipoles in a linear array, which improves wideband performance, is examined. A long wire with multiple feeds is the model, using rigorous moment method analysis. Edge waves of current appear not to be attenuated; around half-wave dipole length the current peaks are one wavelength apart, with deep nulls. For dipole(More)