Neptune Technology R450, Руководство по установке и обслуживанию

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System Certification
The Andrews antenna supplied with the R450 DC is specified as
having a VSWR of 1.5:1 or better over the 450 - 470 MHz range.
Measuring VSWR at the R450 DC must take into account losses in
the feed line. For instructions, see “Measuring the VSWR” on page
68. The easiest approach is to use return loss instead of VSWR. The
1.5:1 VSWR translates into a return loss of 13.98dB. Refer to Table
15 below, Table 16 on the facing page and Table 18 on page 98 to
assist with the calculation.
It is recommended that the feed line be certified as a separate step.
This is best performed by putting a known amount of power into one
end of the cable and verifying that, after correcting for the cable
losses, the correct amount of power is coming out the other end.
Power Measurement
Input Power
1W 5W 10W
Reflected Power Reading Return Loss VSWR
0.001 0.005 0.01 30.0 1.07
0.002 0.010 0.02 27.0 1.09
0.003 0.015 0.03 25.2 1.12
0.004 0.020 0.04 24.0 1.14
0.005 0.025 0.05 23.0 1.15
0.006 0.030 0.06 22.2 1.17
0.007 0.035 0.07 21.5 1.18
0.008 0.040 0.08 21.0 1.20
0.009 0.045 0.09
20.5 1.21
0.010 0.050 0.10 20.0 1.22
0.020 0.100 0.20 17.0 1.33
0.030 0.150 0.30 15.2 1.42
0.040 0.200 0.40 14.0 1.50
Table 15 – Power Measurement to Return Loss and
VSWR Conversion Table -Part I
90 R450 Data Collector Installation and Maintenance Guide
Appendix A: RF Antenna Installation