Owen Duffy wrote:

Reversed connections and/or unequal feeder lengths certainly can be
used, but they are advanced techniques requiring clear intent and
careful engineering. In all other cases they will be "WRONG" as Gordon
says.

I received comment on my antenna described at
http://www.vk1od.net/4over4/ as follows: 'It "doesn't" work because you
have inserted a half-wave time delay in the feed to one antenna (in
your case it appears to be the upper antenna) which tilts the beam up
or down a bit (in your antenna, it will tilt upwards)' and in following
discussion it is asserted that although the feed to one antenna is
transposed, it does not correct the additional half wave phase shift of
the longer branch.

Gordon's paper was offered as support for that position.

Your version of the 4/4 is phased correctly as shown. The extra
electrical half-wave compensates for the gamma match being on the
opposite side, as both are equivalent to a 180deg phase shift.

Gordon's paper does not deal with situations where the use of different
lengths of feedline is deliberate.


I think my design is sound, the rationale is set out in the article. I
am a little flattered if it is considered an advanced technique, but it
seems to me fairly elementary.

It cannot be done without *first* knowing how to make two lengths of
feedline exactly equal, so that's got to be "more advanced"... er,
right?


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek