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I'd like to use 40 m for short distance (ground wave) QRP CW. My criteria for antenna selection is simple:

  • Works short distance (ground wave)
  • As simple as possible
  • As small as possible
  • Ideally, some degree of portability

What antenna is a good choice for that, and how should it be deployed?

My reading suggests a 40 m dipole. However, most of the guides I've seen talk about how to deploy it for increased distance (= high angle of radiation). That seems to be the opposite of my goal. Is there a smaller antenna I can use? Or a better way to deploy it?

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A dipole is not very portable, nor "small", if by that you mean, small area needed for deployment. A vertical, would be the most space efficient, requiring only one anchor point, 20M or so, off the ground. This would be an end-fed halfwave antenna, requiring a 49:1 UnUn transformer, with a very short counterpoise. The second most space efficient would be a halfwave, inverted L; this is the same construction as the end-fed halfwave vertical antenna, except after going straight up for as high as you can, your wire goes horizontal for the rest of its length. Obviously, this requires two "sky-hooks", but if you have more horizonal ability than vertical, it is still far better than a ground-mounted 1/4 wave vertical.

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  • $\begingroup$ It seems easier to me to string a 1/2 wave antenna horizontally than to erect almost anything vertically, especially if it will perform decently when low to the ground. Since I can roll the dipole up into a coil, put it in my car, and unwrap it where I go, I consider it portable and "small", more than say an erect 1/4 wave. $\endgroup$
    – SRobertJames
    Commented Jun 18 at 1:49
  • $\begingroup$ Certainly a sloping configuration will work, it just changes the radiation pattern. A center-fed dipole, while easy to build because it doesn't require a transformer, does need three anchoring points, which doesn't make it a first choice if you want a portable, fast and easy antenna to deploy. $\endgroup$
    – Louis Seaman
    Commented Jun 18 at 10:04
  • $\begingroup$ That raises a good question: What is the radiation pattern of a center fed dipole on the ground? $\endgroup$
    – SRobertJames
    Commented Jun 18 at 12:53
  • $\begingroup$ @SRobertJames if you really mean groundwave, horizontal antennas have approximately zero groundwave prop. Only vertically-polarized signals travel in groundwave. (On the other hand, a low horizontal dipole can do NVIS). $\endgroup$
    – hobbs - KC2G
    Commented Jun 20 at 13:29

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