Hi Joe, KK0SD
Or you can place the patches side by side and crossed by 90 degrees with one of them advanced 1/4 wavelengt (1.23") free space in the axial direction and feed them with equal feed line lenght.
It is easer because these panels are patch style antennas already supplyed with the same lenght of coax cable and a connector but in any case you need a power splitter with characteristic impedance of 35 ohm to transform the 25 ohm of the paralleled antennas to the 50 ohm of the main feed line or a load as a preamplifier.
The problem here is that since they are pach style antennas you cannot establish immediately if crossing one patch vertically polarized and the other one orizontally polarized the generated CP is RHCP or LHCP and you need to make a measurement of circularity sense of radiation with respect to a reference CP antenna as for example an helix antenna.
Just in case you want RHCP and instead you get LHCP it is sufficient to rotate one patch by 180 degrees and the sense of the current flowing in the side of the patch where the coax is connected will flow in the opposite direction reversing LHCP to RHCP and vice versa.
The best solution instead to use two HG2414P linear paches is to buy only one circularly polarized patch model HG2409PCR if you need to radiate RHCP or a model HG09PCL if you need to radiate LHCP
To illuminate a dish and radiate or receive RHCP from reflection on it's surface for use on satellites hopefully P3E in the future ? it is necessary the patch model HG09PCL wich radiates LHCP toward the dish.
By the way a patch antenna has a lobe of radiation of about 150 degrees wide at the -10 dB points and as a feed it is suitable for dishes having a very low F/D ratio under 0.45 to prevent spillover.
Tanks to John ,W9EN to provide me with the internet address in order to find the technical data of the above WiFi panels.
The HG2414P is a linearly polarized patch. http://www.34t.com/PDF/hg2414p.pdf
The HG2409PC is a circular polarized patch (LH or RH available). http://www.34t.com/PDF/hg2409pc.pdf
73" de
i8CVS Domenico
----- Original Message ----- From: "Gary "Joe" Mayfield" gary_mayfield@hotmail.com Cc: amsat-bb@amsat.org Sent: Tuesday, June 08, 2010 4:53 AM Subject: [amsat-bb] Re: CP antenna from 2 WiFi panels
You can place them side by side and introduce the delay in the feed line
of
one as well.
73, Joe kk0sd
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of John Belstner Sent: Monday, June 07, 2010 9:37 AM To: Greg D. Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: CP antenna from 2 WiFi panels
Hi Greg,
These panels are patch style antennas and as such you will not be able to place one behind the other to obtain circular polarization. Placing one next to the other will at best produce an elliptically polarized pattern, and you should use a 50 ohm splitter to keep your impedance 50 ohms. The shape of the patch and position of the feed point is typically how you obtain circular polarization with a patch antenna.
Or, you can obtain RHCP with the same or more gain and less trouble by making a Helix. A sheet of aluminum, #8 copper wire and and a piece of
PVC
of the right diameter is all you need. http://brneurosci.org/helix-antenna.html
Or, you can try just a single panel and see how it performs for a while.
Good luck!
73, John W9EN DM13le W9EN@AMSAT.ORG
On Jun 6, 2010, at 1:15 PM, Greg D. wrote:
Hi folks,
Before I start nailing stuff together, I just want to verify what I'm
doing...
I want to make a 2.4ghz Right-Hand Circular antenna from two flat panel
Wi-Fi antennas. The idea is to mount them at 90 degrees from each other, with one 1/4 wavelength in front of the other. Combine the two feeds with
a
simple Tee (the feeds are of equal length), and into the pre-amp. Since
I'm
not transmitting, I'm not too worried about the resulting 25 ohm impedance (or should I be?).
If it matters, the panels are from HyperLink Technologies, their model
HG2414P, with a claimed 14dBi gain.
So, the questions:
- 1/4 wavelength at 2401 mhz is ((3 x 10**8 / 2401 x 10**6) / 4)
meters,
or about 1.23 inches. Right?
- Most of our 2.4 ghz satellite downlinks seem to be either linear or
RHCP, so I'm guessing that RHCP is probably the preferred construction. (Yes?)
- Looking at the Satellite Experimenter's Handbook (figure 7-10), I
believe the panel rotated 90 degrees counter-clockwise as seen from behind the panels should be the one farther out in front, for RHCP. (Their
picture
shows clockwise for LHCP.) Is this correct?
Thanks,
Greg KO6TH
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars
with
Hotmail.
http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=P...
326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_5
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