Agilent Technologies N9340A manual Making a Reflection Calibration Measurement

Making Measurements 3

Making a Reflection Calibration Measurement

The following procedure makes a reflection measurement using a coupler or directional bridge to measure the return loss of a filter. This example uses a 370 MHz low- pass filter as the DUT.

The calibration standard for reflection measurements is usually a short circuit connected at the reference plane (the point at which the device under test (DUT) is connected.) See Figure

19.A short circuit has a reflection coefficient of 1 (0 dB return loss). It reflects all incident power and provides a convenient 0 dB reference.

1Connect the DUT to the directional bridge or coupler as shown below. Terminate the unconnected port of the DUT.

Figure 20 Reflection Measurement Short Calibration Test Setup

Short Circuit

Or

DUT

Coupled

Port

N9340A

1	2	3
4	5	6
7	8	9
	0

	If possible, use a coupler or bridge with the correct test
N O T E
	port connector for both calibrating and measuring. Any
	adapter between the test port and DUT degrades
	coupler/bridge directivity and system source match.
	Ideally, you should use the same adapter for the
	calibration and the measurement. Be sure to terminate the
	second port of a two port device.
N9340A User’s Guide		51