LED RF Signal Strength Meter

RF Signal Strength Meter circuits are popular RF measurement devices. This circuit is one of the simplest but very useful circuit that satisfies your desired accuracy. The heart of measurement is high accuracy but easy to use Logarithmic Detector AD8313 manufactured by Analog Devices company.

To indicate the result, an LED train model indicator with 10dbm steps is used. As you can see in the schematic, 10 LEDs are drive by a Dot/Bar Display Driver LM3914 manufactured by National Semiconductor company. This type of indication enables you to use it as an FOX hunter / RF Spy Finder device with a proper antenna.

Notes:
C3,C4 and C5 are SMT/25V/X7R/100nF
C7 and C8 are SMT/50V/NP0/680pF
R1,R2,R3,R4 and R5 are SMT/5%
R6,R7 and R8 are THD/1%
Solder SMT resistors and capacitors as near as possible to leads of AD8313.