Active Antenna With Gain


Posted on Apr 10, 2012

The signal booster, built around a few transistors and support components, offers an RF gain of about 12 to 18 dB


Active Antenna With Gain
Click here to download the full size of the above Circuit.

(from about 100 kHz to over 30 MHz). The RF signal is direct-coupled from Ql"s source terminal to the base of Q2, which is configured as a voltage amplifier. The output of Q2 is then direct-coupled to the base of Q3 (configured as an emitter-follower amplifier). Transistor Q3 is used to match and isolate the gain stage from the receiver"s RF-input circuitry. Inductor LI is used to keep any power source noise from reaching the FET (Ql) and any value of RF choke from 0.5 to 2.5 mH will do. The value of R2 sets the Q2 bias at about 2 V. If the voltage is less than 2 V, increase the value of R2 to 1.5 KOhmhm. To go below 100 kHz (to the bottom of the RF spectrum), increase the value of CI to 0.002uf. The antenna is a short pull-up type (42" to 86" long).




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

AM reciever with MK484
Phase tracking three-phase generator
Diode Sensor For Lasers
USB to RS232 Using Atmel ATtiny2313 or ATmega8
diy tremolo effect circuit
Schematics VHF FM Receiver TDA7000 88-108 MHz
oscillator
RF VOLTMETER
ACU7505 chip MP3 player memory circuit
DC-coupled multi-stage amplifier circuit b



Top