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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4552XAYZ7NCIZ34OPIKBKM45UQECOSNU/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "002701c91a8c$6be2a950$0b09a8c0@zeus",
    "message_id_hash": "4552XAYZ7NCIZ34OPIKBKM45UQECOSNU",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/4BHUMOXIE6CGC7MAJOES2B4RQNVWB3CO/",
    "sender": {
        "address": "sv1bsx (a) yahoo.gr",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "SV1BSX",
    "subject": "[amsat-bb] Re: Polarity questions",
    "date": "2008-09-19T19:17:47Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/5R67TX3PCUFAO7KWITKTNI773VUKYV7O/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "....I agree with Gus. And the difference is 20-30 dB depending upon the\nconstruction, reflections,\nlobes of antennas and other complex parameters.\n\n In general a Cross-Yagi which appears a very good circularity, then rising\neasily to 30 dB\nbetween RHCP-LHCP.\n\n Tim,\n also keep in mind, by using CP the fading is much less and never the signal\nhas\ntoo much \"deep\" .\nHaving in mind that the LEOs changing quite often the polarization, I\nbelieve the\nswitching between RHCP-LHCP is mandatory,  if always you looking for good\nRX-TX conditions .  A mere example was the last pass of AO-7 over my QTH .\nDuring the ascending orbit it was 5 S-units without preamp and almost close\nto TCA the signal\ndropped down to Zero (Q5). By changing my antenna to the opposite\npolarization,\nit was again 5 S-units. That is a great difference on receiving.\n\n  So, If you want just to play with LEOs and you are not looking for the\noptimum,\nyou can do it by using stable polarization. However it's compromise\nand manytimes you will wonder why the satellite is too weak and some other\ntimes \"booming\".\n\n\n73, Mak SV1BSX\n\n\n\n\n----- Original Message ----- \nFrom: \"Angus\" <[email protected]>\nTo: <[email protected]>\nSent: Friday, September 19, 2008 5:29 PM\nSubject: [amsat-bb] Re: Polarity questions\n\n\n> if the satellite is running RHCP and you have LHCP the VHF/UHF Manual\n> handbook says 20 -30dB which is a lot!\n> having spent ages getting a homebrew polarity control box to work just\n> right, I can honestly say it was well worth the effort!\n> regards\n> Gus M0IKB\n> ----- Original Message ----- \n> From: \"Tim Tapio\" <[email protected]>\n> To: <[email protected]>\n> Sent: Friday, September 19, 2008 1:58 PM\n> Subject: [amsat-bb] Polarity questions\n>\n>\n>>\n>> Hi,\n>>\n>> How much signal reduction is there as the result of having the wrong\n>> circular polarization?\n>> I'm looking at M2 circular antennas for the 70cm downlink, it's another\n>> $200\n>> for the switching to change polarity (woo hoo).\n>>\n>> 73 de Tim, K4SHF\n>>\n>>\n>>\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> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n\n",
    "attachments": []
}