[Elecraft] New list member/T1 tuner questions

[Ron D'Eau Claire]

Rick, it's the fact that adjacent half wave sections are out of phase that
skews the main lobes toward the far end of the wire. That's why a "long
wire" must be at least 1 wavelength long in order to have at least two
adjacent half wave sections. 

But the gain of a one wavelength "long wire" is only about 3 dBi; only about
1 dB better than a dipole, and the main lobes are still nearly at right
angles to the wire as in a dipole. 

At two wavelengths the main lobes are about 40 degrees from the end and show
a gain of about 5 dBi.

At four wavelengths the main lobes are about 25 degrees off from the ends
and now and the gain is about 6 dBi, and it increases with longer wires of
course.

You can get similar gain from a center fed antenna, but only when each side
approaches several wavelengths. Often such dual "long wires" are arranged in
a horizontal "V" shape to produce considerable gain, or they are extended
into the diamond shape known as a rhombic. With the correct proportions and
angles the lobes from the various sections all add to form one large lobe. 

It's probably better to classify these antennas by their more technical name
of "Traveling Wave Antennas", although at just what dimension in wavelengths
a wire becomes a traveling wave antenna is subjective. 

You didn't mention which books you have, but an excellent one that is very
popular among Hams is "HF Antennas for all Locations" by Les Moxon, G6XN or
any of the ARRL Antenna manuals. Both of these avoid the heavy math often
found in other manuals such as John Kraus' "Antennas" that has become
something of a classic in engineering schools, at least here in the USA, and
they go into these principles in considerable detail.

73,  

Ron AC7AC

-----Original Message-----

Hmmm... isn't a definition of a "long wire" one in which alternate half
wave
sections are out of phase? [[snip]]

In all the books I've read it says that a long wire is a wire that is one
wavelength or multiples of one wavelength at the lowest frequency and
radiation of a long wire is basically off the ends of such wire.  It has
nothing to do with phase....

73 - Rick McKee, KC8AON
Southern Ohio - EM88sn
www.angelfire.com/electronic2/qrp
With God all things are possible ~ ><(('> ~