Колинеарни антени. Фазираща намотка.
#1
Много хубаво представяне на принципа на фазирана колинеарна антена: https://owenduffy.net/antenna/ccps/index.htm
Симулация + изпълнение на колинеарна антена с фазираща намотка: https://www.hamradio.me/antennas/improvi...per-j.html
Калкукатор за многоелементна колинеарна антена: https://hamuniverse.com/wb3aywcollinear.html
J-Pole антена: https://en.wikipedia.org/wiki/J-pole_antenna
The Case of the Curly Collinear: http://www.on5au.be/content/a10/vhf/cc.html

Коментари от форум: https://forums.qrz.com/index.php?threads...on.341311/
Цитат:Phasing coils are tricky. They're not just inductors, just as phasing "transmission lines" aren't simply transmission lines. To start it's worth looking at VK1OD's analysis of quarter wave stubs:

http://vk1od.net/antenna/ccps/index.htm

especially noting that the common mode current on the transmission line is critical for the proper operation of the phasing. A lumped transmission line won't do, neither will a lumped inductor or any other kind of purely "two terminal" device. Now, I have achieved a decent collinear model with a couple dB gain with just an inductor but it required longer elements. The current distribution looks like this:

http://n3ox.net/files/collinear.png

That antenna's current distribution is probably best described as a 3/2 wavelength wire with the usual alternating phase relationship but where the middle 1/2 wave has been inductively loaded so that it's physically small. It has about the same center current as the other elements but does not contribute as much to the radiation from the antenna because it's short. Ideally you'd minimize the out of phase radiation by shrinking that center section as much as possible. I believe that a collinear with coils uses a self-resonant short helical section to do exactly that.

If you want to use just a coil in between half waves I am not sure how to design that but I can suggest a untested (as far as I know) procedure using ON4AA's coil calculator:

http://hamwaves.com/antennas/inductance.html

In the "intermediate results" there is a parameter called β, with units of radians per meter. If you multiply β by the physical length of the coil you get the electrical length in radians according to the coil model in use there. If you put in some coil parameters and fiddle until you get the product of the coil length and β to be equal to pi radians (180 degrees) then I believe the coil may be close to what you need for a phasing coil.

But I haven't tried it yet.


Прикачени файлове Миниатюри
   

.xls   wb3ayw1collinearjpole5eleWB3AYWfeed12.xls (Размер: 122.5 KB / Сваляния: 0)
Отговори


Отваряне на:


Потребители разглеждащи темата: 1 гост(и)