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 pieplate) 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 tuneable loading coil


 
 

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


 
 

Click here for electrical model

Click here for construction details

Click here for 3D simulation of antenna radiation pattern

Click here for 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 right photo but it IS there.

Updated 12/3/1999