Drink Lots Of Beer To Raise Your Monopole

When we published a piece about an ADS-B antenna using a Coke can as a groundplane, Hackaday reader [2ftg] got in contact with us about something with a bit more… stature.

A monopole groundplane antenna is a single vertical conductor mounted on an insulator and rising up above a conductive groundplane. In radio terms the groundplane is supposed to look as something of a mirror, to provide a reflection of what would come from the other half of a dipole were there to be two conductors. You can use anything conductive as your monopole, a piece of wire, (in radio amateur humour) a piece of wet string, or even beer cans. “Beer cans?” you ask incredulously, expecting this to be another joke. Yes, beer cans, and [2ftg] has been good enough to supply us with a few examples. The first is a 57-foot stack of them welded together in the 1950s for use on the 80 metre band ( we suspect steel cans may have been more common than aluminum back then), the second is a more modest erection for the 2 metre band, and the final one consists of photographs only of an HF version that looks a little wavy and whose cans are a little less beery.

The reporting in the 1950s piece is rather cheesy, but does give a reasonable description of it requiring welding rods as reinforcement. It also gives evidence of the antenna’s effectiveness, showing that it could work the world. Hardly surprising, given that a decent monopole is a decent monopole no matter how many pints of ale you have dispatched in its making.

The Coke can ADSB can be seen in all its glory here, and if all this amateur radio business sounds interesting, here’s an introduction.

Beer cans picture: Visitor7 [CC BY-SA 3.0].

17 thoughts on “Drink Lots Of Beer To Raise Your Monopole

  1. ” ( we suspect steel cans may have been more common than aluminum back then)”
    I recall hearing “new” all aluminum (aluminium – Jenny) beer can commercials during the mid to latter 1960’s.

    1. First aluminum beer can was a slow-production version from Coors in late 1950s, with Reynolds Aluminum getting into the act in 1963 – ish. Exemplary Scientific American article here [PDF]:http://www.chymist.com/Aluminum%20can.pdf

      My late uncle used to use the soldered can antennas on his farm for his shortwave adventures.

      These were not welded – welding thin sheet metal like that can be a pain for the average homebuilder and would create an immediate corrosion problem, but soldering/brazing steel with a torch is easy since the body seams on the steel cans were soldered tight anyway. (Yep, lead in your beer – and everything else – the food industry discontinued its use in the 1970s and it was banned by the FDA in 1995).

      Sláinte

  2. The antenna featured it the last beer can antenna was not a ground plane as claimed here according to the drawing accompanying the article, It was a dipole made of two 1/4 wave elements! However as the length of the can in the previous article is a full 1/4 wave in length it has not been shortened slightly as it would need to be because its diameter is very wide. So the previous antenna was a wrongly calculated half wave that might work partially as a ground plane antenna because one of the elements is too long and flat at the top? To be sure it would have been nice with a simulation in an antenna sim program.

    1. It’s kind of hard to find cans in different lengths. So unless you cut them, and that won’t look as good, you’re stuck with lengths rounded off to the length of a can.

      Michael

      1. I was mentioning the article a few days ago about an ADS-B antenna, which in refereed to in this article as a ground plane antenna. I’m not complaining about the mast made of cans in this article.

  3. I might be missing the point… But in an engineering context, the mirror image antenna is just a modelling construct to ensure the boundary condition (i.e. ground plane = ground) is met. Nothing to do with reflection in the physical sense…

    1. A ground plane antenna have different lobes to a dipole, and at lower frequencies where Earth is the ground plane, the difference it’s obvious, but I might be wrong, antennas are still partially black magic and a lot of designs depend on people arguing on why a specific design work in a certain way.

  4. In my personal project I am using esp-wroom32. Now I am using access point as esp-wroom32.now i have to send broadcasting messages to esp devices more than 20.

    it is possible to use only one access point or not

    plz help me.

  5. People also make discone antennas using chicken-wire as cone, and in some rare cases even the disc made from chicken-wire although I don’t think that’s a good plan.
    Anyway the point being that chicken-wire is usable as various form of ground plane. With the note that due to the thinness and sensitivity to oxidation you might want to avoid it in wet areas if you want to use it for more than a week.

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