A.M. Broadcast Antennas by W5CDT

A.M. Broadcast Antennas

by W5CDT

Shown below is my 1st prototype of an A.M. broadcast antenna for 1610KHz.

Don't laugh!!! It's resonant, has a 1.1:1 VSWR, and works AMAZINGLY well.

The goal was to keep it under 9.8 feet in length to comply with FCC part 15.219.

Tuning is very touchy and bandwidth is always narrow for such short antennas for

1.6MHz operation. The capacitive "hat" (a pie plate) was my lazy way of lowering

the frequency by adding capacitance. To be strictly FCC legal you should

resonate your antenna without the capacitive "hat".


Shown Below is my 2nd prototype with tune-able loading coil


 

Below is a close up of the tapped loading coil and tuning capacitor arrangement


 

Electrical model


Construction details


3D simulation of antenna radiation pattern

Cross sectional power plot relative to 1/4 wave antenna


After getting it all working I weatherproofed the air variable

capacitor in a nice box as shown below in the two photos...

it's hard to see the box in the photo but it IS there.


 
 

Updated 12/3/1999



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