HP 8530A, Руководство по эксплуатации и программированию, Страница: 237 / 439

Time Domain RCS Measurements
Range Gating
The HP 8530A Gating feature allows you to selectively view individual portions of the Time
Domain response . Once you gate out unwanted Time Domain responses , you can then view
the data in the Frequency Domain: the eects of the Time Domain responses outside of the
gate will be removed. F or RCS measurements , this allows the user to gate out unwanted RCS
responses (those that originate outside the target zone). Thus , gating mathematically removes
undesired responses from both time and Frequency Domain data. Refer to Figure 13-8 .
A Gate is a band-pass shaped Time Domain lter . The user has direct control over the gate
width and location. There are three Gate indicators:
ST ART and STOP The Gate ST ART and STOP indicate the 06 dB cuto times .
Gate SP AN = STOP 0 ST ART .
CENTER The GA TE CENTER indicates the center time (not frequency) of this
lter .
A Gate has a bandpass lter shape , as shown in Figure 13-7.
Figure 13-7. Typical Gate Shape
Gating Example
This example demonstrates the use of gating to reduce the eects of unwanted RCS responses
when measuring a metal sphere . The gate is centered around the target zone and, with the
gate applied, the eects of the responses outside the gate are removed. In the Frequency
Domain, this removes the high frequency ripple from the response . Figure 13-8 shows the
eects of gating in the Frequency and Time Domains .
13-12 Introduction to Time Domain RCS and
Antenna Measurements