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Old November 2nd 04, 04:04 PM
Richard Clark
 
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On Tue, 2 Nov 2004 15:28:39 +0100, "Kasper Vibe Grevsen"
wrote:
thanks for your suggestion,

that means a T-shape as I understand?
The horizontal part should be 2 x 30,7 mm, right?
How long should the vertical line be?
How wide should I make the tracks?
The cable is a 50 ohm coax.


Hi Klaus,

Although perfection requires precision and accuracy, your application
does not demand perfection. Besides, it is unlikely you are either
technically prepared to measure the properties of the antenna, nor buy
equipment that could do it simpler.

There are any number of factors that would impact the measurements you
describe above and one is simply building the antenna on a piece of PC
board (why not simply use wire?). Another point is that the dipole is
a "balanced" design, and your source of radiation is undoubtedly
"unbalanced." This, of course, probably means nothing to you, and
fortunately it has meant nothing to many who have ignored this
distinction too (which underlines that perfection is not required in
ordinary, day-to-day usage). Also, you don't include enough
information to offer an exact solution.

However, to answer your question by the parts:

Yes it is T shaped (see ASCII graphic below with fixed font);

Yes, the horizontal part should be about 2 x 30,7 mm;

The vertical lineS should be as long as they take to reach
the source
and
the ground;

The Horizontal tracks could be as wide as 1mm - if you make them wider
this reduces your need for precision if you wanted to be perfect;

If you are going to use 50 Ohm cable, you don't need vertical leads.

The pictorial equivalent (view with fixed font setting):

----------- -----------
| |
| |
| |
| |
| |

Returning to issues of perfection. If you encounter problems of
reception/transmission, they will be more due to the antenna
orientation and placement than they will be due to power level.

Back when we lived in caves, TV came through the air instead of
through a cable. We had rituals to adjust Rabbit Ear antennas (a
pagan WiMax shrine) until the picture got better. You are about to
embark in that same arcane practice - welcome to a brave new world.

73's
Richard Clark, KB7QHC