Prev: Any experience with RadioLab GS2000 wireless bridge?
Next: Router problems.
From: jimmie68 on 25 Aug 2008 14:26
On Aug 2, 2:28 am, m...(a)sushi.com wrote:
> On Aug 1, 5:09 pm, jimmi...(a)gmail.com wrote:
>
>
>
>
>
> > On Aug 1, 4:33 pm, jimmi...(a)gmail.com wrote:
>
> > > On Jul 31, 1:12 am, m...(a)sushi.com wrote:
>
> > > > On Jul 30, 1:57 pm, jimmi...(a)gmail.com wrote:
>
> > > > > On Jul 29, 11:47 pm, m...(a)sushi.com wrote:
>
> > > > > > On Jul 29, 1:52 pm, jimmi...(a)gmail.com wrote:
>
> > > > > > > In WiFi is there any standard convention for the polarity of a helical
> > > > > > > antenna. I am building a 40 turn unit and wanted to know whether I
> > > > > > > should build it right or left handed.
>
> > > > > > > Yes I know this will only matter when trying to connect with other
> > > > > > > systems that use circular polarity.
>
> > > > > > > Jimmie
>
> > > > > > Please post how it works out. Also, have you considered building a 4
> > > > > > 10 turn helix (heli?) and run in parallel. That gets around the
> > > > > > matching issue.
>
> > > > > Yes, I thought about that but I have plans for the 40 turn unit
> > > > > including the matching device. Also I have access to a Network
> > > > > Analyzer and S pararamter test set for tuning it up. I think building
> > > > > the matching network may be easier than build a phasing harness for 4
> > > > > Helix antennas. However I have never done this before so plans may
> > > > > change. Who knows, if things work out OK I may build a 4 X 40 turn
> > > > > device.
>
> > > > > Jimmie
>
> > > > My guess is paralleling the 4 helix antennas would have a broader
> > > > bandwidth than the impedance matched solution. Broadband is good in
> > > > the sense that it allows for more error in the construction.- Hide quoted text -
>
> > > > - Show quoted text -
>
> > > Usually paralelling(stacking) antennas means a narrower bandwidth.
> > > This statement assumes all the stacked antennas are identical.
>
> > > Jimmie- Hide quoted text -
>
> > > - Show quoted text -
>
> > This should be of interest to anyo one wanting to build a helix
> > antena.
>
> >http://www.qsl.net/ve3cvg/antennas/2400/
>
> > Jimmie
>
> When I build antennas, I try to use all copper if I can. Otherwise,
> you get a battery connecting Al to copper. I'm not sure about
> connecting copper to galvanized. I've built a few log periodics (VHF/
> UHF) and used that gunk (OK, not a technical term) used with Al
> wiring. Still, it deteriorates with time.  Consider using copper wire.
>
> Have you considered the biquad? Unless you have circular polarization
> on both ends, you will lose 3db when interfacing with linear polarized
> antennas, so 16db becomes 13db, which is close to the biquad.
>
> I guess a long helix would be better for snooping purposes since not
> everyone is vertically polarized.- Hide quoted text -
>
> - Show quoted text -

I found the helix not to be such a good antenna for point to point in
this case.
The final design was a 10 element Quagi( quad driven element and
reflector
with yagi directors). The Quagi has the advantage of being polarity
selective.
The antennas were mounted for horizontal polarity thus rejecting much
of the
mostly vertically polarized interference.

I also discovered that on the WRT54s that the antenna ports can be
operated
with one port as transmit and the other receive at least if you are
running
DD WRT software .


Jimmie
First  |  Prev  | 
Pages: 1 2 3 4 5
Prev: Any experience with RadioLab GS2000 wireless bridge?
Next: Router problems.