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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/J3GVSQJA6T5GMNX3MB2D6WKBXSKUTGBN/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "J3GVSQJA6T5GMNX3MB2D6WKBXSKUTGBN",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/GYUOJV5ZAADWYRL2TVSQO5RLO533I3IT/?format=api",
    "sender": {
        "address": "mattpatt (a) 1starnet.com",
        "mailman_id": "499e0e622b0c492ba956e4a42322498f",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/499e0e622b0c492ba956e4a42322498f/emails/?format=api"
    },
    "sender_name": "Matt Patterson",
    "subject": "[amsat-bb] Re: J-Pole Antenna",
    "date": "2013-05-13T18:57:41Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/KHWXT2R7CFYIKZVDMMROW7HV7FZDWIQF/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Back when I was on the FM sats I used a small yagi for 2m and another \none for 70cm.   I built a mast out of some 2\" PVC that came out to a T \nand had 45 degree elbows on it.  I then mounted the antennas on the \nelbows so that they were pointed roughly 45 degree up.  The whole thing \nwas mounted to a cheap radio shack rotator.  The rotator was mounted to \na metal fence post (t-post).  The antennas were maybe 7' off the ground \nat the highest point.   I could work just about all passes with this \nsetup.  Using one radio for RX and another radio for TX.  Only passes I \ncouldn't work were either real low or I would loose signal for a few \nminutes when I had overhead pass.  Do a google on my callsign and you'll \nfind several recordings I made of suitesat with this setup that I have \nuploaded to Soundcloud.\n\n73 Matt\nW5LL\n\nOn 5/13/2013 1:02 PM, Werner, HB9BNK wrote:\n> Thank you for your advice - very much appreciated.\n>\n> The beauty of the J-Pole, I have in mind, is, that it contains both 2m \n> and 70cm Systems on one mast - so I could simply attach the two cables \n> going to the IC910 directly .... hi\n>\n> The little yagi, I used, has a gain of 5.5 dBd for 2 meters and 8 dBd \n> for 70 cm. So, I guess, you say, investing time for the defunct rotor \n> is better spent than trying omni.\n>\n> Yes, I must find a solution for this.\n>\n>\n>\n>\n> Am 13.05.2013 19:12, schrieb Robert Bruninga:\n>>> The antenna, that I want to build, is described in a paper (probably 20\n>> years old)\n>>> by Dick, WD4FAB, titled 'Antennas for microsat ground stations', and \n>>> the\n>> paper\n>>> describes the large time, a LEO remains at low elevations - about 76 %\n>> below 20 degrees -\n>>> and then concludes, that this is fine for a J-Pole.\n>>\n>> Absolutely true with respect to the*antenna pattern* but the current \n>> batch\n>> of LEO satelltes even though they are in the main beam of the omni \n>> antenna\n>> at the horizon, are -too-far-away- to be heard with only 2.1 dB of omni\n>> dipole antenna gain.\n>>\n>> So yes, those are good \"satellite antennas\" for omni coverage, but they\n>> wont hear anything that low because the satellites are 3000km away \n>> and the\n>> current crop of satliltes mostly operate in the 1/2 watt or less area.\n>> The only thing you will hear down to the horizon with these antetnnas is\n>> the ISS that is operating at 10 watts or more.\n>>\n>> You are better off simply giving up on the horizon (for an omni) and\n>> increasing your gain higher up.  And a 1/4 wave whip over a ground \n>> screen\n>> will give you 5.1 dBi instead of 2.1 dBi.  And then you may begin to \n>> hear\n>> things above about 15 degrees or so (and 3 dB better than you would hear\n>> on any antenna optimized for the horizon..\n>>\n>> And it is even better  to go to a 3/4 wave vertical over a ground screen\n>> and then you get almost 7 dBi gain starting around 30 degrees.  You wont\n>> hear the low satellites (you can't anyway on an omni) but you will hear\n>> them much better when they do get above about 25 degrees... (but notice,\n>> this is less than 1/4th of all passes).\n>>\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 \n> program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n>\n>\n\n\n",
    "attachments": []
}