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  • A sensitive and reliable rf field strength meter is an invaluable instrument in amateur radio and in radio controlled model area. A field strength meter is used to align an antenna to get the best possible gain, to determine the transmitting range of radio controllers …

    Designing the rf field strength meter to be sensitive it is a requirement because there must be as many wavelengths as possible between the meter and the transmitter, the measurement can be done without using a stronger carrier signal and most of the radio controllers are of low power type.

    Considering these factors, a dual MOSFET is used as an RF amplifier in this circuit. The amplification can be adjusted by P1 and with S1 switch we can select three frequency ranges:
    L1 – 480 kHz to 2.4 MHz
    L2 – 2.4 MHz to 12 MHz
    L3 – 12 MHz to 40 MHz
    The antenna is made of 30 cm long metal rod.

    The rf field strength meter circuit schematic

    field strength meter circuit schematic

    Active components: 3N140, 3SK35, 3SK37

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    3 Responses to "RF Field Strength Meter Circuit"

    1. euripedes de souza neves pp2bbd says: on May 25, 2012 at 5:11 pm

      muito bom, bom mesmo.

    2. euripedes de souza neves pp2bbd says: on May 25, 2012 at 5:12 pm

      fiz e deu tudo certo.

    3. r de vreede says: on October 22, 2014 at 11:35 pm

      Years done model flying and rf racing and never seen a. metre, i don’t see the use for it, but usefull to see the radiation between your gear and when using the real anti rf plates, watching the results, and now building a switch for an emi circuit measurement.

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