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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/SGTDKUWNLR26SHDGDWWBXD3QW3TMVDRK/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "743786DCB77A4B25A6103BF8844D6C92@kc6uqh",
    "message_id_hash": "SGTDKUWNLR26SHDGDWWBXD3QW3TMVDRK",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/43CTXJMT5OLQ3GNXNBH6ML5GAX4U537W/?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: Polarity questions",
    "date": "2008-09-21T15:35:38Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/JTGNMC3T4ADX6VZGNQBHKGJKYM5BJLDX/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Nate,\nThe advantages of circular when both antennas are circular is not the 3 dB\ngain, but the ability to except the rotation of the antenna without signal\nchange and cancellation of the first reflection (reduction of multipath\nfading) which produces steady signals.\nYagi types are subject to receiving reflections from the side and are only\ncircular polarization on the on axis lobe. Off axis reverse circular\nrejection is limited to the forward gain and side lobe rejection of a Yagi\nantenna. Helix and QFH antennas are circular over the entire envelope.\nThe use of dish reflectors on frequencies of 1.2 GHz and above is\nrecommended. There are several designs, one in an old AMSAT Journal of a\npatch feed and polarity switch that works well as a RH/LH circular feed for\nthe popular TVRO satellite dishes that are abundant.\n\nArt,\nKC6UQH \n \n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]] On\nBehalf Of Nate Duehr\nSent: Saturday, September 20, 2008 11:29 PM\nTo: AMSAT BB\nSubject: [amsat-bb] Re: Polarity questions\n\n\nOn Sep 20, 2008, at 2:07 PM, Edward Cole wrote:\n\n>\n>\n> At 01:53 AM 9/20/2008, Luc Leblanc wrote:\n>> On 20 Sep 2008 at 0:56, Nate Duehr wrote:\n>> ======snip\n\nThat was a weird snip... made it look like my comments were left in  \nthat question and statement from Luc.\n\nI do have a question for the polarity gurus, however...\n\nWhen *transmitting* circular vs. linear polarity, are the apparent  \nlosses the reverse of the numbers being used for receiving?  I am  \ninclined to think that has to be true.\n\nOr to put it as a question:  With all else being equal, including  \nantenna gain numbers...\n\nHow much more power has to be put into a circularly-polarized antenna  \nversus a linearly polarized one of the same gain, to have a distant  \nstation receive the same signal if they're linearly polarized?\n\nI'm purposely coming at this from the \"other\" direction... the  \ntransmit side, instead of what is seen at the receiver.\n\nThis is mostly a mental exercise to see if I \"get it\".  So if it's a  \ngoofy way to analyze it, ignore that for a moment...\n\n--\nNate Duehr, WY0X\[email protected]\n\n\n\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 3458 (20080921) __________\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 3458 (20080921) __________\n\nThe message was checked by ESET NOD32 Antivirus.\n\nhttp://www.eset.com\n \n\n",
    "attachments": []
}