By Institute of Electrical and Electronics Engineers. Antenna Standards Committee
Read or Download IEEE Std.149-1979 Test Procedures for Antennas PDF
Best electrical & electronics books
Additional resources for IEEE Std.149-1979 Test Procedures for Antennas
The bandwidth of the first intermediate-frequency amplifier is typically of the order of 10 MHz, while that of the second intermediate-frequency amplifier is of the order of 100 Hz. ly 200 Hz. This is in contrast to that of the conventional receiver employing square-law detection. The noise bandwidth of the latter is approximately dm; where B1 is the bandwidth of the intermediate-frequency amplifier and B,, the bandwidth of the postdetection amplifier. Typically B, and B, are chosen to be 1 MHz and 100 Hz, respectively.
The actual size of the quiet zone may, for example, be specified in terms of the direct wave from the source antenna, that is, by specifying the a,mplitude and phase variations of the direct wave from the center of the quiet zone to the edge of the zone. Then the “quietness” of the zone is dependent upon the magnitudes of the reflections from the walls, floor, and ceiling 55 IEEE Std 149-1979 SPECIAL MEASUREMENT of the chamber. There is no standardized figure of merit for anechoic chambers. What is done is to establish the ratio of an “equivalent” reflected wave, that is, the aggregate effect of all reflected waves incident upon the probe antenna used to test the chamber, to the direct wave.
For some systems ampli- carries the local oscillator power to the mixer tude modulation is required; hence the signal and provides the return of the intermediatesources should have that capability. There are frequency signal from the mixer to the receiver. cases where special pulse shaping is required This places a limitation on the allowable cable attenuation for proper mixing, usually about to reduce the distortion of the pulse spectrum. 15 dB. 4 Receiving Systems. The receiving subsys- manual and motor-driven tuning.