Wireless and Microwave Instructional Laboratory

Laboratory #9 Notes

The purpose of this laboratory exercise is to introduce you to the following:
1. The construction of mixers by using nonlinear elements.
2. The use of RF harmonic tuning, RF open circuits, and RF chokes to maximize power at desired frequencies and minimize power at other frequencies.
For this exercise you will need to turn in the following items:
1. Summmary
2. Discussion of Results
3. Printouts and Tables as Given at the end of the Laboratory Write-Up
4. Laboratory Write-Up Including Experimental Results

Notes on Experiment 9

The coupler serves to add the LO and RF signals at the input. The diode is a nonlinear element. Remember that a nonlinear element causes harmonics to appear. The diode serves to "mix" the signals. The harmonic tuning stub and the RF choke rid the unwanted components from the output.

In the optional section on Video Detector Measurement, you should not only remove the wire to the DC return path, but you should also remove the wire to the RF choke. This is not mentioned in the laboratory write-up. If you do not remove the RF choke, the DC output of the diode will be shorted to ground and no DC voltage will be measured by the multimeter.

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