Posted on Thursday, June 23, 2011 • Category: FM Transmitters
Most transmitter has several variable capacitors which are used to match impedance for transistors and antennas. I know people hate trimmers and so did I. The reason is that it is difficult to trim a system if you can't measure the performances.
To trim a transmitter you need to measure the output power.
Most transmitter are tuned with a dummy load of 50 ohm to substitute an antenna of 50 ohm.
Not everyone has a power meter, and how can you know that the antenna you connect is purely 50 ohm.
If not, the hole trimming is waste of time!
What you would like to do is to measure the radiated power out from the antenna you actually are going to use.
If you can measure the radiated energy field you can easy tune the system for max output field strength (max power).
So, how can we measure the radiated energy field?
The block diagram at right show you one easy way to measure the RF filed strength. To the left you find a dipole antenna.
The antenna should be cut to match the receiving frequency ...
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