3-2 PN: 10580-00321 Rev. M S331L UG
3-2 Common RF Terms Cable and Antenna Measurements
3-2 Common RF Terms
3 dB rule: A 3 dB gain means twice (x2) the power. A 3 dB loss means
half the power. A system with 40 watts of input power and a 6 dB
insertion loss will only have 10 watts of output power.
dB: Decibel, a logarithm (equal to 10 times) ratio of the difference
between two values. The Site Master uses dB to measure the ratio of
sent signal energy to reflected signal energy.
Common values of dB to ratios: 0 dB = 1:1, 10 dB = 10:1, 20 dB = 100:1,
30 dB = 1,000:1, -30 dB = 0.001:1. or (1/1000):1.
dBm: An absolute measurement of power relative to 1 milliwatt.
0 dBm = 1.0 milliwatt, 10 dBm = 10 milliwatt, 30 dBm = (1 mW x 1,000)
= 1 watt.
DTF (Distance to Fault): Measures the location and reflection size of
impedance mismatches. This is typically a diagnostic measurement, not
a pass/fail judgement measurement. DTF is used to identify and locate
faults within an antenna system when the system is failing to meet the
specified return loss/VSWR limits. DTF is also useful to verify the total
length of a coaxial cable assembly.
Impedance: A measure of an RF components electrical resistance.
Measured in ohms (Ω). In most cable and antenna systems the standard
impedance is 50 Ω.
4 Measurement Type
5 Marker 2 (Marker to Valley)
6 Stop Frequency (F2)
7 Pass Message (Active trace is below the limit line in Return Loss
measurement)
8 Marker Table
9 Start Frequency
10 Measurement Details (also Menu Shortcuts)
11 User-defined Setup and Menu Shortcuts (not available in Classic
mode)
Figure 3-1. Cable and Antenna Display Overview (2 of 2)
To Next Page
Loading...
Need help?
General
