Wednesday, October 10, 2018
Antenna feeding receiver
The impedance along the half-wave antenna is as shown. When you attach a half-wave antenna to a 50 Ohm amp input your amp loads the 2500 Ohm antenna. Making a center tap and feeding it to get a 73 Ohm feed point would better match you amp. It will be directional and have to be pointed in the right direction.
Yet Another Book called for but one more point. The propagation speed in the conductor is slower than free space so the antenna will be about 90% of the calculated value at optimum. It will be close enough for testing but in a transmitter we would make it to the calculated value and trim a little at a time till we find the best length or use an antenna tuner. You can read about that when you get the book.
Posted by Reset at 10:40 PM