Agilent Technologies HP 70910A Podręcznik Użytkownika Pobierz pdf (Strona 114)

114 Chapter 4

Performance Tests

2. Image Rejection Test

Performance Tests

2. Image Rejection Test

Description

The image rejection is checked at an LO power level of +15.2 dBm. A known input power is

applied to the input of the mixer. The IF output power is measured on an 8566B Spectrum

Analyzer at the input signal frequency and at the image response frequency. From the

measurements, the image rejection is determined. The image response appears on the

spectrum analyzer at a frequency of two times the IF frequency higher than the actual

signal frequency. In the case of the 8566B, the image response appears 642.8 MHz above

the actual frequency of the signal.

Procedure

1. Connect an SMA cable from the 1ST LO OUTPUT of the spectrum analyzer to the

INPUT of the 11975A Amplifier. Connect a second SMA cable to the OUTPUT of the

amplifier.

2. Connect the 8481A Power Sensor to the power meter sensor cable, then zero and

calibrate the 436A Power Meter.

3. Set the spectrum analyzer controls as follows:

SHIFT ⇑ ⇑ ⇑ ⇑ (selects U Band)

FREQUENCY SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz

CENTER FREQUENCY (sets LO frequency to 5.0 GHz) . . . . . . . . . 50.3 GHz

CAUTION When you are using an 11975A Amplifier with an 11974, you must set the

amplifier rear-panel ALC switch to ON before you connect the amplifier to the

test setup. If the ALC switch is left in the OFF position, the amplifier output

power is high enough to destroy the mixer diodes.

4. On the 11975A Amplifier, set the rear-panel ALC switch to ON, then connect the 8481A

Power Sensor to the free end of the cable installed on the OUTPUT connector of the

amplifier. Set the 436A Power Meter Cal Factor % to the appropriate value for a

frequency of 5 GHz.

5. Adjust the amplifier OUTPUT POWER LEVEL for a reading of +15.2 dBm

±0.1 dBm on

the power meter.

6. Connect the equipment as shown in Figure 4-1 on page 106.

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Agilent Technologies HP 70910A Podręcznik Użytkownika Strona 114