You re measuring field strength from a transmitting vhf antenna use a vhf an tenna on the field strength meter.
Field strength meter circuit diagram.
I built it but it didn t work well so i changed a few components to get better sensitivity.
To use turn on transmitter and meter.
The inputs signal across the conducting discs is applied to the non inverting input of ic1.
The variable resistor on the field strength meter figure 3 the case circuit board and antennas for the field.
Adjust c1 for peak reading.
This circuit can be used to detect magnetic field strength of radio signal and common radio transmitting signal through antenna.
The rf field strength meter circuit schematic.
I built it but it didn t work well so i changed a few components to get better sensitivity.
This field strength meter uses an 1ma fsd ammeter dc and indicates the radio magnetic field strength between 0 to 1ma scale range.
This circuit help us to.
This circuit is another radio frequency rf field strength meter similar with our previous field strength meter circuit but with lower supply voltage only a single cell 1 5v battery.
Here is the schematic diagram of this rf strength meter circuit.
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.
I saw this circuit in an old issue of 73 radio electronics.
Start your measurements by using low transmitter power and a near minimum sensitivity on the field strength meter.
The capacitor c3 and inductor l1 forms a tuned circuit to receive a particular frequency the frequency of your transmitter the diode d1 detects the signal and applies to the base of transistor q1 mpsa 18 the collector current of the q1 will be proportional to the strength of this signal and will be shown in the meter m1 in result the meter reading will be a measure of the strength of the.
The field strength is measured by converting the radio signal to dc and measuring it.
This is a simple and low cost wide band vhf field strength meter.
The unit discussed here indicates by means of a chain of leds in logarithmetic ratios the strength of an electric field surrounding the unit.
A field strength meter fsm is a very useful circuit to detect and measure the rf signals and their strength.
How to build field strength meter.
Simple field strength meter circuit is designed by using single transistor and few easily available components.
The circuit shown here can be used as a wide band field strength meter and can field strength meter.
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.
The rf signal will be picked up by the coil and rectified by the diode d1 even a very small dc voltage is sufficient to alter the biasing of fet and it will be reflected in the meter as an indication of the presence of a radio signal.
I saw this circuit in an old issue of 73 radio electronics.
