An active antenna for the 160-80-40m bands
Edsard Boelen, 09-mei-2014
It seems that transmitting on the 160M band is not very difficult, receiving is harder.
The idea is to make an active antenna specially for those frequencies.
There are several designs available: loop, whip and mini-whip.
The standard 1m active antenna.
I will begin with the 1m active antenna. It will just amplify the signal of 100KHz-30MHz with 12-20dB.
The principle is as follows: a high impedance input mosfet followed by a low impedance output BJT.
It doesn't really matter which transistors and mosfets are used, but the High frequency versions DO have a very low noice.
The power is supplied over the coax cable by placing 9V via 2 coils.
in the elektor of 2006 the following enhanced circuit was posted:
It consists of a antenna part and a receiver part.
short introduction to mini-wip antenna
a very nice explanation of the fundamentals can be found
the original article can be found here