CP antenna from 2 WiFi panels
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. 1/4 wavelength at 2401 mhz is ((3 x 10**8 / 2401 x 10**6) / 4) meters, or about 1.23 inches. Right?
2. 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?)
3. 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...
----- Original Message ----- From: "Greg D." [email protected] To: [email protected] Sent: Sunday, June 06, 2010 10:15 PM Subject: [amsat-bb] CP antenna from 2 WiFi panels
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?).
Hi Greg, KO6TH
You should be worried because even on receiving your VSWR is 50/25 = 2 and since the downconverter has been tuned for the lovest noise figure with a 50 ohm noise source it happens that the noise generated by your downconverter will be greater than you should expect with an input VSWR = 1
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?
Right, but 1.23 inches is a too short distance to mechanically separate by 1/4 wavelenght two flat panels so that if necessary it will more convenient to use for spacing an odd numbar of 1/4 wavelenghts into free space at 2401 MHz and use two coax feed lines of the same lenght.
- 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?)
All 2.4 GHz downlinks on the actual satellites are linear so that no matter if you connect the antenna for RHCP or LHCP
- 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?
It depends if you connect the inner conductor of the coax cables to A or to A' for the front dipole and to B or to B' for the rear dipole.
In a separate email I will send to you a drawing to explain how two linearly polarized waves radiated as a 90° components combines each other to generate a resultant wave that can be RHCP or LHCP.
Thanks,
Greg KO6TH
73" de
i8CVS Domenico
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 [email protected]
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... _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
----- Original Message ----- From: "John Belstner" [email protected] To: "Greg D." [email protected] Cc: [email protected] Sent: Monday, June 07, 2010 4:37 PM 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 [email protected]
Hi John, W9EN
I would like to know if these panels are patch style antennas linearly or circularly polarized.
Tanks
73" de
i8CVS Domenico
----- Original Message ----- From: "John Belstner" [email protected] To: "Greg D." [email protected] Cc: [email protected] Sent: Monday, June 07, 2010 4:37 PM 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 [email protected]
Hi John, W9EN
I would like to know if these panels are patch style antennas linearly or circularly polarized.
Tanks
73" de
i8CVS Domenico
Hi Domenico,
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
They are about the same price too.
73, John
On Jun 7, 2010, at 3:23 PM, i8cvs wrote:
----- Original Message ----- From: "John Belstner" [email protected] To: "Greg D." [email protected] Cc: [email protected] Sent: Monday, June 07, 2010 4:37 PM 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 [email protected]
Hi John, W9EN
I would like to know if these panels are patch style antennas linearly or circularly polarized.
Tanks
73" de
i8CVS Domenico
Thanks, John!
At 02:37 PM 6/7/2010, John Belstner wrote:
Hi Domenico,
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
Just ordered one for $14.99+ shipping. I comes with 12-inch coax with NF connector. Other cables and /or connectors for $36.99
They are about the same price too.
73, John
73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-600w, 432-100w, 1296-60w, 3400-fall 2010 DUBUS Magazine USA Rep [email protected] ======================================
Speaking of pannel
I try to get info's on a square patch antenna made by California Amplifier described as "sich planar antenna/converter" PCS/WCS filtered radar immune. There is a part number NO: 2240/020 Google search does not return anything just a clue as it seems to be in the MMDS or satellite range?
It is a flat pannel with linear polarization as there is V and H arrow marking in the back making the pannel installation mounted as a diamond instead of having the side of the square mounted parallel to the ground.
"-"
Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe DSTAR urcall VE2DWE WAC BASIC CW PHONE SATELLITE
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: [email protected] [mailto:[email protected]] On Behalf Of John Belstner Sent: Monday, June 07, 2010 9:37 AM To: Greg D. Cc: [email protected] 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 [email protected]
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
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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" [email protected] Cc: [email protected] 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: [email protected] [mailto:[email protected]] On Behalf Of John Belstner Sent: Monday, June 07, 2010 9:37 AM To: Greg D. Cc: [email protected] 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 [email protected]
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
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi John,
"At best"? Interesting... I've seen many diagrams about mounting two linear YAGIs at 90 degrees from each other on the same cross arm, with the appropriate phasing harness. My plan is to mount the two panels the same; one next to the other, rotated 45 degrees in opposite directions on the cross arm, with one pushed out 1.23 inches by a block of wood. How bad will this be? One will surely get some elliptical effects when the satellite is off-axis, but keeping them aimed at the satellite is what the rotor and computer are for...
I understand that I'm losing some NF by not using a proper splitter, but I don't have one handy, and this is (was) supposed to be a low effort adventure. Again, for AO-51 VS, I should have plenty of margin.
I've built several helixes, both 2.4 ghz for the feed to my BBQ grill, and my current L-band uplink, and could do the same here. But, back to the low effort part of things...
If this simply isn't going to work, then I'll just leave my current setup alone. It consists of a 3 3/4 turn helix feeding a 30 inch BBQ grill, lined with window screen. All combined, it's kind of heavy, and the wooden cross arm is showing the effects of the weight and its age. It was built for AO-40, and for the current satellites I don't really need this much gain, hence the replacement idea.
Bad idea?
Greg KO6TH
Subject: Re: [amsat-bb] CP antenna from 2 WiFi panels From: [email protected] Date: Mon, 7 Jun 2010 07:37:17 -0700 CC: [email protected] To: [email protected]
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 [email protected]
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... _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PI...
Hi Greg,
What I meant by "at best" is that it will certainly be a challenge (at 2.5 GHz) to get one panel just a perfect 1/4 wavelength forward from the other. It will be equally as challenging (at 2.5 GHz) to make 75 ohm phasing cables some odd multiple of 1/4 wavelength.
I say that because I found it quite challenging to make phasing cables for 1.3 GHz and even 440 MHz and I had a network analyzer to help me. Just when I thought I had it cut perfect I put the connector on and found myself 10 to 20 degrees off. That will affect the circularity of the polarization. I finally gave up and mounted the elements of one yagi 1/4 wavelength forward from the other and used equal length cables.
Physical spacing is easier to achieve within a few degrees at the lower frequencies (VHF/UHF). Another alternative would have been to use a 90 degree broadband hybrid (that can handle 25 watts) but that was much more $ than I wanted to spend.
If you have a helix already, I would use that. But don't let me talk you out of experimentation. It is possible and might be fun.
73, John
Sent from my Verizon Wireless BlackBerry
-----Original Message----- From: Greg D. [email protected] Date: Mon, 7 Jun 2010 20:22:22 To: [email protected] Cc: [email protected] Subject: RE: [amsat-bb] CP antenna from 2 WiFi panels
Hi John,
"At best"? Interesting... I've seen many diagrams about mounting two linear YAGIs at 90 degrees from each other on the same cross arm, with the appropriate phasing harness. My plan is to mount the two panels the same; one next to the other, rotated 45 degrees in opposite directions on the cross arm, with one pushed out 1.23 inches by a block of wood. How bad will this be? One will surely get some elliptical effects when the satellite is off-axis, but keeping them aimed at the satellite is what the rotor and computer are for...
I understand that I'm losing some NF by not using a proper splitter, but I don't have one handy, and this is (was) supposed to be a low effort adventure. Again, for AO-51 VS, I should have plenty of margin.
I've built several helixes, both 2.4 ghz for the feed to my BBQ grill, and my current L-band uplink, and could do the same here. But, back to the low effort part of things...
If this simply isn't going to work, then I'll just leave my current setup alone. It consists of a 3 3/4 turn helix feeding a 30 inch BBQ grill, lined with window screen. All combined, it's kind of heavy, and the wooden cross arm is showing the effects of the weight and its age. It was built for AO-40, and for the current satellites I don't really need this much gain, hence the replacement idea.
Bad idea?
Greg KO6TH
Subject: Re: [amsat-bb] CP antenna from 2 WiFi panels From: [email protected] Date: Mon, 7 Jun 2010 07:37:17 -0700 CC: [email protected] To: [email protected]
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 [email protected]
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... _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PI...
I have made a LH circular patch for 2.4 GHz and mounted it as a feed for a 1'prime focus dish. I have successfully used it on AO 51. The Patch is in air with 1/4 " spacing, The active element is rectangular with 2 opposite clipped corners. It has less than 1 dB of axial ratio. It is fed near one corner at the 50 Ohm point.
Art, KC6UQH
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Belstner Sent: Monday, June 07, 2010 8:47 PM To: Greg D Cc: [email protected] Subject: [amsat-bb] Re: CP antenna from 2 WiFi panels
Hi Greg,
What I meant by "at best" is that it will certainly be a challenge (at 2.5 GHz) to get one panel just a perfect 1/4 wavelength forward from the other. It will be equally as challenging (at 2.5 GHz) to make 75 ohm phasing cables some odd multiple of 1/4 wavelength.
I say that because I found it quite challenging to make phasing cables for 1.3 GHz and even 440 MHz and I had a network analyzer to help me. Just when I thought I had it cut perfect I put the connector on and found myself 10 to 20 degrees off. That will affect the circularity of the polarization. I finally gave up and mounted the elements of one yagi 1/4 wavelength forward from the other and used equal length cables.
Physical spacing is easier to achieve within a few degrees at the lower frequencies (VHF/UHF). Another alternative would have been to use a 90 degree broadband hybrid (that can handle 25 watts) but that was much more $ than I wanted to spend.
If you have a helix already, I would use that. But don't let me talk you out of experimentation. It is possible and might be fun.
73, John
Sent from my Verizon Wireless BlackBerry
-----Original Message----- From: Greg D. [email protected] Date: Mon, 7 Jun 2010 20:22:22 To: [email protected] Cc: [email protected] Subject: RE: [amsat-bb] CP antenna from 2 WiFi panels
Hi John,
"At best"? Interesting... I've seen many diagrams about mounting two linear YAGIs at 90 degrees from each other on the same cross arm, with the appropriate phasing harness. My plan is to mount the two panels the same; one next to the other, rotated 45 degrees in opposite directions on the cross arm, with one pushed out 1.23 inches by a block of wood. How bad will this be? One will surely get some elliptical effects when the satellite is off-axis, but keeping them aimed at the satellite is what the rotor and computer are for...
I understand that I'm losing some NF by not using a proper splitter, but I don't have one handy, and this is (was) supposed to be a low effort adventure. Again, for AO-51 VS, I should have plenty of margin.
I've built several helixes, both 2.4 ghz for the feed to my BBQ grill, and my current L-band uplink, and could do the same here. But, back to the low effort part of things...
If this simply isn't going to work, then I'll just leave my current setup alone. It consists of a 3 3/4 turn helix feeding a 30 inch BBQ grill, lined with window screen. All combined, it's kind of heavy, and the wooden cross arm is showing the effects of the weight and its age. It was built for AO-40, and for the current satellites I don't really need this much gain, hence the replacement idea.
Bad idea?
Greg KO6TH
Subject: Re: [amsat-bb] CP antenna from 2 WiFi panels From: [email protected] Date: Mon, 7 Jun 2010 07:37:17 -0700 CC: [email protected] To: [email protected]
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 [email protected]
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
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participants (8)
-
Art McBride -
Edward R Cole -
Gary "Joe" Mayfield -
Greg D. -
i8cvs -
John Belstner -
John Belstner -
Luc Leblanc