LED RF Signal MeterSelect a picture for larger image.




Overview of the LED RF signal meter.  It's built into an old California Amplifier MMDS downconverter case.  Proper circuit shielding is required for this project.
Closeup of the National LM3914 dot/bar display driver.
Closeup of the Analog Devices AD8313 RF logarithmic detector and power supply regulation/filtering.
Solder side of the LEDs.
Overview showing the insides and battery.
Power on.  The first green LED is a battery indictator, the next two are lit because of background RF noise.
Slightly closer to the RF source...
BINGO!!!  75 Watts!!  Wall-to-wall and tree top tall.

LED RF Signal Meter
 
This is a high quality RF signal meter based around the Analog Devices AD8313 0.1 GHz - 2.5 GHz logarithmic detector IC.  It is capable of detecting signals as low as -80 dBm.  When combined with 2.4 GHz or 915 MHz bandpass filters, it makes a quick visual reference to the amount of noise in the ISM bands in that particular location.
It also makes a handy visual tool for verifying that your antenna is indeed radiating energy.
LED RF Signal Meter Schematic
LED RF Signal Meter Schematic  500 MHz QST version  (20k PostScript)
Pictures of the LED RF Signal Meter
Analog Devices AD8313 Datasheet  (267k PDF)
1 MHz to 950 MHz RF Wave Absortion Meter With LED Signal Indication