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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/LDRZUKQF7O2NTWTLACBY2UJT7OT3FHLA/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "LDRZUKQF7O2NTWTLACBY2UJT7OT3FHLA",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/IWCP55GXC35HB6OHFUZHSYIN2P5UXAP6/?format=api",
    "sender": {
        "address": "terrando (a) gmail.com",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Simone T",
    "subject": "[amsat-bb] Re: 70cm Yagi and AO-51",
    "date": "2008-01-01T17:51:42Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/3FLCUTUPVZBJMEIY3HVMEQYLNGFTRSAB/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Andrew, All,\n\nFirst of all, Happy New Year!\n\nA circular polarization is made of two orthogonal linear polarizations. This\nis why two crossed yagis (each one transmitting and receiving only linear\npolarization) realizes a circular polarized antenna. RHCP ad LHCP results by\nphase-shifting of + or - 90 degrees one of the two signals.\nIf these two signals have exactly the same amplitude, and the phase shift is\nexactly 90 degrees we have an ideal circular polarized signal, this means\nthat the so called \"polarization vector\" rotates on a perfect circumference.\nOf course this in reality is not possible, and our polarization many times\ncan be like an ellipsis (or a potato HI).\n\nSo speaking practically, if your antenna has the wrong circular polarization\n(RHCP instead of LHCP) in theory you should not receive nothing! In reality,\nas the signal polarization has not a perfect circular shape, the actual\nattenuation can be as high as plenty of tenth of dB...\n\nOn the other side, if you use a linear polarized antenna to receive a\ncircular polarized signal, you will loose one half of the power of the\nsignal (no matters if right or left handed), as the circular polarization is\nmade in equal parts by two linear polarized signals. So this means -3dB (At\nleast, in theory...).\n\nLast but not least, if you use a circular polarized antenna to listen to a\nlinear polarized signal, you won't see any difference than using a linear\npolarized antenna. In this case you can have an advantage, as the signal\npolarization can even rotate during its travel, so you'll not have\nadditional losses.\n\nHope this helps.\n\nHappy 2008 to All.\n\n73s\n\nSimone - IW1FYV\n\n\n\n2008/1/1, Andrew Rich <[email protected]>:\n>\n> If I have this correct.\n>\n> 1. LHCP recieved on a RHCP can knock your signal down by some 20dB\n> 2. LHCP matched with LHCP will result in a good signal.\n>\n> So how does a linear antenna equate when receiving a circular signal ?\n>\n> And the other way around, a circular receiving a linear signal ?\n>\n>\n>\n>\n>\n> ----------------------------------------------------------------------------\n> Andrew Rich VK4TEC\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",
    "attachments": []
}