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GET /hyperkitty/api/list/[email protected]/email/AM7TSSKZFC3GB4A573XN5TNODEO5RCRP/?format=api
{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/AM7TSSKZFC3GB4A573XN5TNODEO5RCRP/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "3637B152BF374E98881D4AC738DF75E4@KC6UQH", "message_id_hash": "AM7TSSKZFC3GB4A573XN5TNODEO5RCRP", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/5UJFGVSIGAZSYBLS6NSETVS6RDXEPN3B/?format=api", "sender": { "address": "kc6uqh (a) cox.net", "mailman_id": "d9201820d18047e4a2772c86bda5e111", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/d9201820d18047e4a2772c86bda5e111/emails/?format=api" }, "sender_name": "Art McBride", "subject": "[amsat-bb] Re: CP antenna from 2 WiFi panels", "date": "2010-06-09T05:07:03Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/3C5QMN3KNQMPJUQWPC6F46HW7WR5ZIEA/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "I have made a LH circular patch for 2.4 GHz and mounted it as a feed for a\n1'prime focus dish. I have successfully used it on AO 51. The Patch is in\nair with 1/4 \" spacing, The active element is rectangular with 2 opposite\nclipped corners. It has less than 1 dB of axial ratio. It is fed near one\ncorner at the 50 Ohm point. \n\nArt,\nKC6UQH \n\n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]] On\nBehalf Of John Belstner\nSent: Monday, June 07, 2010 8:47 PM\nTo: Greg D\nCc: [email protected]\nSubject: [amsat-bb] Re: CP antenna from 2 WiFi panels\n\nHi Greg,\n\nWhat I meant by \"at best\" is that it will certainly be a challenge (at 2.5\nGHz) to get one panel just a perfect 1/4 wavelength forward from the other.\nIt will be equally as challenging (at 2.5 GHz) to make 75 ohm phasing cables\nsome odd multiple of 1/4 wavelength. \n\nI say that because I found it quite challenging to make phasing cables for\n1.3 GHz and even 440 MHz and I had a network analyzer to help me. Just when\nI thought I had it cut perfect I put the connector on and found myself 10 to\n20 degrees off. That will affect the circularity of the polarization. I\nfinally gave up and mounted the elements of one yagi 1/4 wavelength forward\nfrom the other and used equal length cables. \n\nPhysical spacing is easier to achieve within a few degrees at the lower\nfrequencies (VHF/UHF). Another alternative would have been to use a 90\ndegree broadband hybrid (that can handle 25 watts) but that was much more $\nthan I wanted to spend.\n\nIf you have a helix already, I would use that. But don't let me talk you\nout of experimentation. It is possible and might be fun.\n\n73, John\n\n\nSent from my Verizon Wireless BlackBerry\n\n-----Original Message-----\nFrom: Greg D. <[email protected]>\nDate: Mon, 7 Jun 2010 20:22:22 \nTo: <[email protected]>\nCc: <[email protected]>\nSubject: RE: [amsat-bb] CP antenna from 2 WiFi panels\n\n\nHi John,\n\n\"At best\"? Interesting... I've seen many diagrams about mounting two\nlinear YAGIs at 90 degrees from each other on the same cross arm, with the\nappropriate phasing harness. My plan is to mount the two panels the same;\none next to the other, rotated 45 degrees in opposite directions on the\ncross arm, with one pushed out 1.23 inches by a block of wood. How bad will\nthis be? One will surely get some elliptical effects when the satellite is\noff-axis, but keeping them aimed at the satellite is what the rotor and\ncomputer are for...\n\nI understand that I'm losing some NF by not using a proper splitter, but I\ndon't have one handy, and this is (was) supposed to be a low effort\nadventure. Again, for AO-51 VS, I should have plenty of margin.\n\nI've built several helixes, both 2.4 ghz for the feed to my BBQ grill, and\nmy current L-band uplink, and could do the same here. But, back to the low\neffort part of things...\n\nIf this simply isn't going to work, then I'll just leave my current setup\nalone. It consists of a 3 3/4 turn helix feeding a 30 inch BBQ grill, lined\nwith window screen. All combined, it's kind of heavy, and the wooden cross\narm is showing the effects of the weight and its age. It was built for\nAO-40, and for the current satellites I don't really need this much gain,\nhence the replacement idea. \n\nBad idea?\n\nGreg KO6TH\n\n\n\n\n> Subject: Re: [amsat-bb] CP antenna from 2 WiFi panels\n> From: [email protected]\n> Date: Mon, 7 Jun 2010 07:37:17 -0700\n> CC: [email protected]\n> To: [email protected]\n> \n> Hi Greg,\n> \n> These panels are patch style antennas and as such you will not be able to\nplace one behind the other to obtain circular polarization. Placing one\nnext to the other will at best produce an elliptically polarized pattern,\nand you should use a 50 ohm splitter to keep your impedance 50 ohms. The\nshape of the patch and position of the feed point is typically how you\nobtain circular polarization with a patch antenna.\n> \n> Or, you can obtain RHCP with the same or more gain and less trouble by\nmaking a Helix. A sheet of aluminum, #8 copper wire and and a piece of PVC\nof the right diameter is all you need.\n> http://brneurosci.org/helix-antenna.html\n> \n> Or, you can try just a single panel and see how it performs for a while.\n> \n> Good luck!\n> \n> 73, John W9EN\n> DM13le\n> [email protected]\n> \n> \n> \n> \n> \n> \n> \n> \n> On Jun 6, 2010, at 1:15 PM, Greg D. wrote:\n> \n> > \n> > Hi folks,\n> > \n> > Before I start nailing stuff together, I just want to verify what I'm\ndoing...\n> > \n> > I want to make a 2.4ghz Right-Hand Circular antenna from two flat panel\nWi-Fi antennas. The idea is to mount them at 90 degrees from each other,\nwith one 1/4 wavelength in front of the other. Combine the two feeds with a\nsimple Tee (the feeds are of equal length), and into the pre-amp. Since I'm\nnot transmitting, I'm not too worried about the resulting 25 ohm impedance\n(or should I be?).\n> > \n> > If it matters, the panels are from HyperLink Technologies, their model\nHG2414P, with a claimed 14dBi gain.\n> > \n> > So, the questions:\n> > \n> > 1. 1/4 wavelength at 2401 mhz is ((3 x 10**8 / 2401 x 10**6) / 4)\nmeters, or about 1.23 inches. Right?\n> > \n> > 2. Most of our 2.4 ghz satellite downlinks seem to be either linear or\nRHCP, so I'm guessing that RHCP is probably the preferred construction.\n(Yes?) \n> > \n> > 3. Looking at the Satellite Experimenter's Handbook (figure 7-10), I\nbelieve the panel rotated 90 degrees counter-clockwise as seen from behind\nthe panels should be the one farther out in front, for RHCP. (Their picture\nshows clockwise for LHCP.) Is this correct?\n> > \n> > Thanks,\n> > \n> > Greg KO6TH\n> > \t\t \t \t\t \n> >_________________________________________________________________\n> > The New Busy think 9 to 5 is a cute idea. Combine multiple calendars\nwith Hotmail. \n> >\nhttp://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID28\n326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_5\n> >_______________________________________________\n> > Sent via [email protected]. Opinions expressed are those of the author.\n> > Not an AMSAT-NA member? Join now to support the amateur satellite\nprogram!\n> > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n> \n \t\t \t \t\t \n_________________________________________________________________\nThe New Busy is not the too busy. Combine all your e-mail accounts with\nHotmail.\nhttp://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID283\n26::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4\n_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n__________ Information from ESET NOD32 Antivirus, version of virus signature\ndatabase 5180 (20100607) __________\n\nThe message was checked by ESET NOD32 Antivirus.\n\nhttp://www.eset.com\n\n\n \n\n__________ Information from ESET NOD32 Antivirus, version of virus signature\ndatabase 5180 (20100607) __________\n\nThe message was checked by ESET NOD32 Antivirus.\n\nhttp://www.eset.com\n \n\n__________ Information from ESET NOD32 Antivirus, version of virus signature\ndatabase 5183 (20100608) __________\n\nThe message was checked by ESET NOD32 Antivirus.\n\nhttp://www.eset.com\n \n \n\n__________ Information from ESET NOD32 Antivirus, version of virus signature\ndatabase 5183 (20100608) __________\n\nThe message was checked by ESET NOD32 Antivirus.\n\nhttp://www.eset.com\n \n\n", "attachments": [] }