On 29/10/14 16:27, Jeff wrote:

Maybe I've missed something here, but I would expect a half-wave dipole
to out-perform a full-wave dipole at the same frequency, despite being
half the size.

Define what you mean by "out perform"!!!

A 1/2 wave dipole will half a max gain of about 2.14db in free space
broadside to the antenna, a full wave dipole will be a little over 3db.
However, if you examine the pattern of the full wave compared to the 1/2
wave the lobes of the full wave will be narrower. ie although more power
is radiated in a direction normal to the antenna less is radiated in
other directions, or to put is another way all of the power applied to
the antenna structure is radiated in both cases, but the full wave
concentrates to more into the direction normal to the antenna.

Of course this does not take into account any losses associated with
matching the full wave.

Jeff

OK, Jeff, I don't think I worded that too well. I've never bothered to
learn complex mathematical formulae just for the sake of it. I prefer to
try to visualise things as simply as I can make them.
In the case of a half-wave dipole, at the instant the voltage at one end
goes to peak positive the other end will be at peak negative, and
maximum current will flow.
In a full wave dipole the voltage at both ends will always be in phase,
so I would expect to see a very high impedance at the feed point.
As you point out, matching the full-wave could be difficult and very lossy.
--
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73 de Frank Turner-Smith G3VKI - mine's a pint.
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