Active GPS antenna Standard Wave Ratio (SWR) test
		GO

SWR test

The RF signals from the GPS satellites are extremely low-level microwave signals that must reach the RFTG with minimal distortion and loss. To verify the RF integrity of the complete antenna and cable system, a Standing Wave Ratio (SWR) or Distance-to-Fault (DTF) test should be performed.

Since the GPS antenna is an active device, a standard SWR or DTF test setup cannot be used. A Bias-T must be employed to inject + 5 VDC into the RF line to power the antenna's Low Noise Amplifier (see Figure below).

Important!  The antenna will meet it's specified SWR only when powered in this way.

Calibrate the Wiltron as shown and per the manufacturer's instructions. Perform the SWR or DTF measurement as shown and per the manufacturer's instructions. Record the MAX SWR indicated and/or DTF data. If it MAX SWR is greater than 2.5, the fault must be repaired and the antenna and cable retested.

		GO
© Alcatel-Lucent