Central heating pipe antenna for SW

If you happen to live in an apartment with steel central heater pipes and you don’t have the option to make yourself an external antenna, due to e.g. thermal insulation, this might probably be the best indoor shortwave antenna for portable world band radios; when it comes to signal (or noise) strength. The latter happens in unfortunate cases, when there are just many switched mode-based modern electronics around. However, along with a simple attenuating circuit, it beats any indoor long- or random-wire setup. I use this indoor gizmo on my Degen DE1103 for casual shortwave number or oddity stations hunting; and the results were spectacular: positioned in central Europe in an apartment block, I have managed to catch Cuba, Libya, Vietnam or even Bangkok with this setup, besides other stations. So, here’s how!

Central heater pipe antenna schematicSchematic

As you can see, this circuit is the simplest example of an RX antenna attenuator. For the input jack, use as short connections as possible. Use the potentiometer in combination with the internal attenuation circuitry of your world band radio to prevent overloading. Thus, if there’s too much noise in your reception, or stations “bleeding through”, increase resistance between the antenna jack and coaxial.

Central heating pipe antenna, AttenuatorAttenuator potentiometer

Then, connect the center conductor of your coaxial directly to any uncovered part of your pipes (find one with no paint/lacquer), and it’s done. Shielding is connected only to the negative pole of your receiver, please see the note below.

Central heating pipe antenna, connectedAll set

Do not try to use this antenna on any receiver which is connected to ground.
Or, in other words, this antenna can be used for portable, battery-powered world band radios, as mentioned above.
Why this limitation? Technically, steel central heating pipes are directly connected to ground, both literally and electrically. Thus, if you try to connect this setup to a desktop receiver, or to an SDR powered by a computer running on mains, it might not work properly, or it will introduce a lot of QRM (interference). It would be like shorting your antenna jack directly to mains ground.
On the other hand, this is actually a big advantage for battery powered radios; since ground acts as a zero volt potential like a lightning conductor, this setup will also protect your input stage from any static or electrical charges.

If you own a desktop receiver (or any other connected to mains ground in general) and you are still interested in this setup, you will need to make a ferrite antenna out of some suitable ferrite cores, with the central heating pipes in center, like this. Or, try directly winding some 10-15 turns on the pipes. However, you might introduce interference from anything which is near this “coil”, unless you shield it someway.

Summed up, good luck with shortwave listening! 🙂

4 Replies to “Central heating pipe antenna for SW”

  1. Nice experiment, and thanks for documenting it! I had the same idea for DCF77 and was looking whether someone had tried it. The principle should indeed work for long-wave reception in general, and not just DCF77.

    The combination of long waves with SDR sounds interesting, but you say it won’t work well enough. Have you considered, perhaps even tried, to insert a balun or transformer, with the primary side spanning the length of the radiator? I would guess that this should work nicely for horizontally polarised signals — I’m not sure but think all long-wave transmission id horizontally polarised.

  2. Hi.
    I saw this antenna and I would like to have a try with a portable SW radio I have.
    Its a Yupitru MVT7100 but it doesnt have any 3.5 jack for external antenna.
    I can only use the BNC metal antenna the radio has allready or make a BNC jack with your Schematic.
    I dont know if yor Schematic works only for a Degen type radio or it can also work with mine.
    Can you help with a new Schematic how to make the modification for the BNC jack?
    Thank you very much.
    Best regards.

    1. This article is rather a joke and intended for the cheap pocket shortwave “worldband” radios, but nevertheless – you connect the radiator to the center pin of your coaxial, shield stays unused, be sure to use a short cable or else it’ll also act as antenna.


Leave a Reply

Your email address will not be published.