Shortwave active antennas are used to improve the reception of radio signals on the HF bands when users are unable to install a larger passive antenna system. But are they a one size fits all situation or does the raw amplification of shortwave transmissions bring problems of its own.
Here we are going to look at the operation of active antennas and exactly how they can be used to enhance the enjoyment of your hobby along with their drawbacks and a viable alternative to using them at all.
Using Active Antennas
Because a typical shortwave receiver users a tuned ferrite for reception of MW/LW and a telescopic antenna for the rest of the HF bands active antenna kits have been designed to work with both systems.
The HF side of active antennas is a straightforward physical connection to the existing telescopic antenna or through any external socket provided. Improving the performance of the ferrite antenna built into the radio is a little different because without dismantling the radio a physical connection cannot be made. This problem is overcome by attaching the active antennas ferrite rod to the outside of the radio directly inline with the internal ferrite.
Inductive interaction between the two ferrite antennas then gives your shortwave radio a signal boost on the MW and LW bands.
Best use of Active Shortwave Antennas
Unless a degree on intelligent filtering is employed to manipulate the signals the active antenna feeds to your shortwave radio then every bit of noise present on the shortwave bands (and there is a lot of it) is going to get amplified along with the very transmission you want to listen to.
This really limits the effective use of active antennas in shortwave radio reception to those nice clean signals that are just a little bit weak and are a big help when trying to listen to high quality broadcast radio transmissions. Its not to say that these types of antennas cant be used for everything you listen to on the HF bands as long as you understand that they are not a magic bullet to improving noise to signal ratio.
Alternatives to Active Antennas
Installing indoor antennas for use with shortwave radios can be easy enough depending on the type of building and amount of space you have available. An indoor antenna can be completely hidden from view and give a significant increase in performance over shorter amplified shortwave systems.
The one time amplified shortwave antennas do come into their own is for use when traveling where you lack the time, parts and permission to set up anything more permanent.
Shortwave radios photo courtesy Wikipedia