Are you one of these go-getter Field Communication Technicians that puts their hand up for anything? You want to collect all the skills by yesterday?

Advance Mobile Faults you say? Yeah, I can do that boss! πŸ‘Œ

Only to spend the whole fault Googling and quickly teaching yourself each abbreviation and trying to work out what the purpose of an Ericsson Baseband is! I have been there done that.

This fault though is one that I struggled to find clear instruction on...well at least one that links Telstra speak.

Task: Configure your Site Master to measure the return loss on an antenna within a specific frequency. And work out if the fault is inside the hut or outside?

First let's work out what VSWR is and then I will show you how to sweep an antenna for it.
I think the return loss is this way boys!!

What is VSWR & Return Loss?

Voltage Standing Wave Ratio (VSWR):

VSWR is a measure of how efficiently radio-frequency (RF) power is transmitted from a power source, through a transmission line, into a load. If all the power is transmitted to the load, the VSWR is 1:1. If some of the power is reflected back towards the source, the VSWR is higher. A higher VSWR indicates more power is being reflected back, which can cause inefficiencies and potential damage to the system.

Return Loss:

Return Loss is a measure of how well devices or lines are matched. It is the ratio of the reflected power to the incident power, expressed in decibels (dB). A higher return loss indicates better matching and less power being reflected.


Testing VSWR and Return Loss with a Site Master

A Site Master is a handheld device commonly used for testing RF transmission lines and antenna systems.

Here’s how you can test for VSWR and Return Loss using a Site Master:

Setup the Site Master:

  • Turn on the Site Master.
  • Wait for the Selftest.
  • Find the calibration tool.

Select Measurement Mode:

  • Choose either VSWR or Return Loss measurement mode on the Site Master.
  • Set the frequency range you want to test (every time you change this you will have to re-calibrate).
  • Ensure it covers the operational frequency range of your system.

Calibrate the Site Master:

  • Follow the devices calibration prompts.
  • This typically involves connecting a calibration kit that includes an open, short, and load.
Follow the prompts.

Perform the Test:

    • Run the measurement. The Site Master will send an RF signal through the transmission line or antenna.
    • The device will measure the reflected signal and calculate the VSWR and Return Loss.
  1. Analyse the Results:
    • The Site Master will display the results on its screen.
    • For VSWR, look for values close to 1:1, which indicate good matching.
    • For Return Loss, higher values in dB indicate better matching.
πŸ’‘
I will get photos of examples next time I test for it.

Interpretation of Results

  • VSWR:
    • 1:1 to 1.5:1 – Excellent
    • 1.5:1 to 2:1 – Good
    • 2:1 to 3:1 – Acceptable, but may need improvement
    • >3:1 – Poor, requires attention
  • Return Loss:
    • >20 dB – Excellent
    • 15 to 20 dB – Good
    • 10 to 15 dB – Acceptable
    • <10 dB – Poor

More information coming soon.

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