How To License A Trailer In California

DX-Projekt 11m Band

"MAAAAAAX - Dearest of all my friends!" [Vlad Lem - Max Payne 2]

Yes, I post again, because I'm planning on just what it.

is my current project:
"self-a 11m band directional antenna with at least 7 dB gain"

this, I've chosen the following antenna types:

a) 5 Element Yagi Beam
b) 4 element boom Quad


early today (about 3:00 clock) and the day I've researched and in my amateur radio textbooks browsed. Meanwhile, I've learned a lot and almost everything is collected, what do I need to know.


a Yagi-beam consists of a boom (support element) and mounted on the elements (reflector, reflector and director (s)):





This structure applies to the Yagi and for the Quad.
The elements are arranged at different intervals on the boom.
is here that the reflector 0.2 λ and 0.1 λ, the director is removed from the radiator. The sum of the distances then gives the length of the boom.






Just yesterday, I spoke to the calculations the lengths and distances begun.
calculated the length of the elements as follows:


Yagi Beam
~~~~~~~~~~
λ = 300 / frequency (in MHz)
l = λ / 2 * VF (emitter length) with

: λ
: electrical length (lambda)
l: length
VF: Reduction factor (eg, Cu 0.667)


Boom Quad
~~~~~~~~~~
λ = 300 / frequency (in MHz)
l = λ / 4 * VF (sides of the radiator)


The length of the reflector is 5% higher than that of the radiator, the Director of the 5% less than that of the Radiator.



The distances of the elements (Yagi and Quad), this results in:

l = 0.1 * λ (spotlight -> director)
l = 0.2 * λ (spotlight -> Reflector)



extent.

Now just follow the connection of the coaxial cable to the antenna. And here it becomes difficult.
The problem is that
1) the antenna impedance other than the coax (50 Ohm)
has 2) and balanced antenna and the coax is unbalanced. Here
must appropriate adjustments.

The Quad can be realized, the more easily by putting them down so that they are in an has feed impedance of 50 ohms. It is then only the symmetric / asymmetric adjustment means standing wave trap is necessary.
A simple standing wave trap you can build from 30cm Teflon coax (RG142) and ferrite beads. can
http://www.spiderbeam.com/documents/index.php?coID=28

Otherwise you Imedanztransformation and the sym / asym-matching using 1:2 Balun with: The pattern to be found here on page 20 Ferrite realize ( http://www.qth.at/oe7opj/homemade-balun_1-2.htm ). For 14 to 30 MHz according to only 5-7 coils are necessary.

The Yagi is more difficult. There are several possibilities, the most common of the gamma-match is. Alternatively, there is still the DK7ZB-Match ( http://www.qsl.net/dk7zb/dk7zb-match.htm ) by means of two parallel coaxial cables.

As the gamma match is calculated, I know the time yet. There are some references to the Aufbei here (gamma matching):
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=13291


so far.