Monday Quiz: RF power measurements

Article By : Martin Rowe

RF and microwave engineers as well as those who design RF modules into products often have to measure transmitter power and power at the receiver.

If you design any IC, subsystem, or complete product that uses wireless technology (and what doesn't these days?), you may have to measure RF power. After all, too little power can result in poor reception while too much can cause components to overload, burn out, or distort signals.

Questions from this week's quiz are based on "Principles of Power Measurement: A Primer on RF & Microwave Power Measurement" by Boonton, part of Wireless Telecom Group. This paper is quite long (148 pages) and thus it just might be a source of questions for a future quiz.

1. Why is it generally not sufficient to measure power by measuring and AC signal's voltage and current? Choose the best answer.

a. If there is a phase shift between current and voltage, there will be times that the voltage and current are of opposite polarities, resulting in a negative power flow.
b. Voltage and current don't equal power, except in special circumstances.
c. Wireless signals are subject to reflections from nearby objects, rendering power measurements impractical.
d. RF signals have frequencies that are too fast to measure.
e. Power measurements work at DC only.
f. None of the above.

Next: Answer & Question 2

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