automatic RF matching unit

HI!
I have to design a automatic matching unit for the frequency range:
1 - 20 MHz. It must be also fast.

The antenna will be a long dipole, about 50 meters tip to tip.

Any advice, circuit, paper? Or anything that could help me.
Thanks.

http://www.maxx-com.com/

I have to design the circuit, thanks for the link,
but I need schematics