Sensors / Detectors: RF (Radio Frequency) Detectors

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RF Detectors: #'s - B C - O P - R S- Z
Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E.:

2.45GHz RF Signal Detector
This passive RF indicator hobby circuit is made from a few simple parts. A bent piece of wire forms a 2.5GHz antenna. A 100uA moving coil meter is used to display the relative intensity of the RF signal. Two microwave rated detector diodes form a simple voltage doubler circuit, which feeds a DC voltage to the meter movement, proportional to the RF field strength. This circuit can be used with some cell phones and many cordless telephones. It can also detect RF leaking from a microwave oven.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

2 Watt Switching Power Supply - In this small switching power supply, a Schmitt trigger oscillator is used to drive a switching transistor that supplies current to a small inductor. Energy is stored in the inductor while the transistor is on, and released into the load circuit when the transistor switches off. The output voltage is dependent on the load resistance and is limited by a zener diode that stops the oscillator when the voltage reaches about 14 volts. Higher or lower voltages can be obtained by adjusting the voltage divider that feeds the zener diode. The efficiency is about 80% using a high Q inductor...(added 3/06)

2.45GHz RF Signal Detector - Many cordless telephones, computer networks and cell phones use a RF transmitter centered on the 2.45GHz band. Using a microwave diode detector and 100uA meter, this passive circuit will display the strength this signal. The drawing shows how a bent piece of wire can be used as the antenna. Posted ….(designed by David A. Johnson)

300 MHz AM RF Remote Control System - (electronic design added 9/02)

300MHz to 3GHz RF Power Detector in SC70 Package - Linear Technology LTC5532 (app note added 02/05)

300MHz to 7GHz RF Power Detector with Buffered Output in SC70 Package - Linear Technology LTC5508 (app note added 02/05)

4 MHz Amplitude Modulated RF Source - A while back I needed an amplitude modulated signal source at 4 MHz. This circuit was literally thrown together with parts laying on the bench. I built it dead bug style on a piece of copper clad board. It should work with little or no modification, other thano get it to oscillate, and at higher frequencies, you might have to reduce the capacitor values a little. Just be...(schematic / circuit added 6/07)

50MHz to 3GHz RF Power Detector with 60dBDynamic Range - Linear Technology LTC5535 (app note added 02/05)

8 Hints for Making Better Measurements Using Analog RF Signal Generators - Agilent Application Note (app note added 3/06)

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