Re: Helix antenna

On Aug 3, 11:49 pm, m...@xxxxxxxxx wrote:
On Aug 2, 8:58 pm, jimmi...@xxxxxxxxx wrote:





On Aug 2, 2:18 am, m...@xxxxxxxxx wrote:

On Aug 1, 1:33 pm, jimmi...@xxxxxxxxx wrote:

On Jul 31, 1:12 am, m...@xxxxxxxxx wrote:

On Jul 30, 1:57 pm, jimmi...@xxxxxxxxx wrote:

On Jul 29, 11:47 pm, m...@xxxxxxxxx wrote:

On Jul 29, 1:52 pm, jimmi...@xxxxxxxxx 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

I see no reason for stacked antennas to have a narrower bandwidth. Can
you elaborate?- Hide quoted text -

- Show quoted text -

Sorry I was thinking of bandwidth in terms of frequency versus VSWR.
This is usally the limiting factor as gain bandwidth is almost always
much broader
than VSWR bandwidth.
As of yet I dont know whether this will be a serious consequence or
not  concerning the helix antenna.

My plan is to build the antenna and tune it for greatest field
strength

A few years ago I stacked 2 2 meter 6 element quad antennas. I had
plans to stack 4 but didnt do it because
of the VSWR excursion from one end of the band to the other.
My solidstate amp was not fond of the 2 to 1 VSWR near the band edges.

In this situation the VSWR bandwidth of 2 antennas was less than 1
antenna and with 4 antennas it was even less.
I am sure the array would have still exhibited considerable gain if I
had a way to readily correct for the impedance changes seen by my
amplifier.

Jimmie

I wonder if the VSWR effects were due to coupling between antennas?- Hide quoted text -

- Show quoted text -

I dont know, the antennas came with printouts from NEC antenna
modeling software. One of the parameters given was a diagram of their
capture area. The antennas were place according to this data with
their capture areas just touching. A local ham who is very much into
antenna modeling verified the data that came with the antennas. At the
time I was surprised by the reccomenced spacing thinking it was
excessive until I discovered that rules saying 1/2 or 5/8 spacing was
not always correct.
.

Relevant Pages

  • Re: Helix antenna
    ... including the matching device. ... Helix antennas. ... Usually paralellingantennas means a narrower bandwidth. ...
    (alt.internet.wireless)
  • Re: Helix antenna
    ... including the matching device. ... Usually paralellingantennas means a narrower bandwidth. ... I see no reason for stacked antennas to have a narrower bandwidth. ...
    (alt.internet.wireless)
  • Re: Helix antenna
    ... including the matching device. ... My guess is paralleling the 4 helix antennas would have a broader ... Usually paralellingantennas means a narrower bandwidth. ...
    (alt.internet.wireless)
  • Re: Helix antenna
    ... However I have never done this before so plans may ... This statement assumes all the stacked antennas are identical. ... Sorry I was thinking of bandwidth in terms of frequency versus VSWR. ...
    (alt.internet.wireless)
  • Re: Helix antenna
    ... This statement assumes all the stacked antennas are identical. ... I see no reason for stacked antennas to have a narrower bandwidth. ... Sorry I was thinking of bandwidth in terms of frequency versus VSWR. ...
    (alt.internet.wireless)