Phase and delay in corporate-fed arrays
The distribution of phase and delay in corporate-fed phased arrays is examined. RMS phase errors versus scan angle are shown for digital phasers. The phaser bits should all be located at each element. The delayer bits can be also, but delayer loss, dispersion, temperature sensitivity, and size mitigate against using so many delayers. Alternative topologies, where delay bits are distributed in the corporate feed, are examined.
Antenna Arrays in the Time Domain: An introduction to timed arrays.
The term phased array comes from the time-harmonic/steady-state analysis of antenna arrays. These arrays use phase shifters to electronically steer the main beam. Phase shifters cause beam squint and pulse dispersion for wide-band signals, so time-delay units are needed to correct these errors. Adaptive and reconfigurable arrays also have time-dependent responses. In addition, time-dependent spurious signals arise due to nonlinearities in amplifiers. This article presents several time-varying issues related to antenna arrays that should not be modeled by the time-harmonic representation of an array. Future antenna arrays will be wideband and time varying, so antenna arrays will have to be designed in the time domain.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.