Contents
What is a SWR power meter?
The standing wave ratio meter, SWR meter, ISWR meter (current “I” SWR), or VSWR meter (voltage SWR) measures the standing wave ratio (SWR) in a transmission line. The meter indirectly measures the degree of mismatch between a transmission line and its load (usually an antenna).
How do you use Astatic SWR power meter?
To Calibrate and Check SWR using the PDC1 meter:
- Set radio on channel 1.
- Set meter to 10W FWD.
- Set meter to SWR.
- Key microphone and turn dial until meter needle goes over to SET.
- Set meter to 100W REF.
- Record SWR reading.
- Repeat steps 2-6 on channel 40.
How is SWR calculated?
happens with a 1:1 SWR. For the case of resistive loads (see sidebar), the SWR can be easily calculated as equal to the (Load R)/Z0 or Z0/(Load R), whichever gives a result greater than or equal to 1.0. The load or terminating resistance is the RF resistance of whatever is on the end of the transmission line.
What does the intersection of two needles mean on a power meter?
The observed intersection of the two needles can be used to indicate the SWR of the system. The lines in the middle of the meter indicate what the SWR is for a given forward and reflected power reading.
How does a cross needle SWR meter work?
These newer swr meters, Fig 2 below, are different from the older style, Fig 1 below, in that there are 2 “needles” that give the swr reading indication when they “cross” each other rather than the older style 1 needle. The 2 different meter types both perform much the same function to get the end result of your swr reading.
What does 1.5 mean on a SWR meter?
Now look back at the red arrow that is pointing to the 1.5 number for a moment on the meter face. The 1.5 represents a 1.5 swr reading “area” and the swr “numbers” go to 0 in a clockwise fashion from that point on the meter face.
How is SWR calculated on a transmission line?
SWR can also be calculated as the ratio of the feed line Z 0 and the load impedance — whichever is greater than 1. Since you already know the feed line’s Z 0 and can measure the load’s impedance, this is a lot more convenient than trying to measure maximum and minimum voltage inside the line: