Basic HF Antennas

After you get your radio, you're next question is likely to be 'what else do I need to hear something on shortwave'. The answer is greatly dependent on many factors. If you are using a portable, the whip antenna will get you started, but generally speaking, that's about it. On HF, these small whips are very inefficient, and would likely capture the stronger signals, but not anything much weaker. Using a desktop, you will need some sort of antenna to hear anything at all.

Portables and Multi Band Handhelds

These radios are designed to work with the relatively small input that a whip antenna would supply; in many cases, putting a substantial antenna on them would cause more grief in the form of overloading than it's worth. Sometimes an extendable whip will help, but you may find you will need to fiddle a bit with the length to get it right.

In most cases, a small hunk of wire - 20 or 30 foot or so - attached to an appropriate plug into the antenna jack on the side of the radio (if it has one) will do. Try to avoid clipping anything directly to the whip (although that will do in a pinch). Any static charges that might build up would likely damage the radio if discharged into the whip. To avoid that same issue with the antenna jack, you can build a small box with some inexpensive diodes which would blow in the case a static charge were encountered. The diagram shown at the bottom of this article includes a small variable resistor (potentiometer) that would serve as a crude RF gain control so you can reduce the level of the signal if needed.

A better solution is a small portable loop, some of which we have links for in our wiki here. There are a couple of advantages; loops are generally less sensitive to electrical noise, and can be moved around so you can find a quiet spot. The better ones have a gain control so you can vary the input level to the current conditions. In addition, most are powered by batteries, so the power drain is quite small.

Portatops, Desktops and Amateur Radio Transceivers

Before you erect anything, survey your property carefully. If the antenna should get knocked down in a storm, will it fall over a power or telephone line? If it would, then find another spot. Remember, safety first.

Every home has appliances in it that generates noise; noise is the bane of the HFer. Ideally, you would want to mount your antenna far enough away from the house to avoid this problem.

The most basic form of the antenna is the inverted L or random length (many folks would call this a 'long wire' - that term should be avoided, as that describes a very different type of antenna). See the article from MT here for a description. This antenna is very broad banded, and easy to construct. Some folks have used coaxial cable as the lead in to help shield against noise pickup.

If you are interested in certain bands, the basic dipole will work well. Be sure to mount it at a height at least 1/4 wavelength from the ground for best results. To find this height, use the standard formula 234/f(mhz) where f(mhz) is the desired frequency in megahertz. Dipoles will also work well on their odd harmonics - so a 3 mhz dipole would work very well on 9 mhz, a 4 mhz dipole would work well on 12, and so on. It is described here.

But I cant put anything outdoors

Anything you put indoors on HF is a compromise. You will have trouble trying to keep from hearing noise sources in the home, you may be constrained as to how much antenna you can put up, home convenants prevent you from putting anything outside - these are just some of the issues.

Active antennas have long been touted as a solution. However, most people don't take the time to learn how to use them properly. We have an article describing active antennas and some of their pitfalls here. If you end up using an active antenna, take the time to try to find a quiet spot in your home where the noise seems to be lowest. Most homes have such places, but it takes hunting to find it. Use an old AM portable (even an old Walkman will do) tuned to an empty channel and walk around your home. It's also worthwhile to take the time to read reviews on active antennas, and see which ones would be good for your application. Check out the HF Antennas wiki for links to reviews.

There are many passive (not amplified) designs that folks have come up with over the years. While they will not perform better than their outdoor cousins, they work well enough to hear some of the weaker and harder to hear stations. The Yahoo group has details of these in their photos and files sections. In addition, our HF Antennas wiki has links to designs and reviews.

Loops are another very good choice for indoor use. Many of the amplified loops mentioned above will work just as well with a desktop as they do with a portable. In addition, if you have some skills with construction, a Carpet Loop is a design worth considering. The advantage here is that you can make the loop element as big as you want (it used 4 or 5 conductor cable which can be placed around the perimeter of a room). You should take advantages of a loop, as it rejects certain kinds of noise (within some limits, and dependent on the surrounding environment). We also have an article on building your own receiving loop here.

Using the attic or crawlspace is a very good idea. It doesn't remove the antenna from the noise sources, but it is sometimes more convienient. You won't have to contend with moving furniture or carpeting, and you might be able to bend the antenna around corners to make it work. Bending a receive antenna generally doesn't adversly effect it all that much; try to avoid bending the antenna back on itself, as that can sometimes cancel a signal out.

Additional Resources

• Loops - Many cover MW as well as HF; some outdoor designs, too
• HF Antennas - Links to designs, diagrams, reviews and much more