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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/RPUGPCRY2TKT5EHSBE2RMASSJQ3G6U7J/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "RPUGPCRY2TKT5EHSBE2RMASSJQ3G6U7J",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/BB7Y3I7UVU5GFOS57DSTXUS3QKIKROWO/",
    "sender": {
        "address": "zleffke (a) vt.edu",
        "mailman_id": "57a24afb1cf641f98121841e6753c12e",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/57a24afb1cf641f98121841e6753c12e/emails/"
    },
    "sender_name": "Zach Leffke",
    "subject": "Re: [amsat-bb] M2 432 polarity switch",
    "date": "2018-03-26T14:24:52Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BB7Y3I7UVU5GFOS57DSTXUS3QKIKROWO/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "We use the M2 polarity switches in the VTGS for both our 70cm and 2m \nantennas.\n\nIn my experience they work very well.  I have not conducted any critical \nanalysis of their performance (Axial ratio measurements and the like), \nbut I can say they are sturdy and solid and in the few years we've had \nthem 'on the tower' I have had no problems with defects or failures (no \nwater ingress or anything like that).  Anecdotally, I will say that \nbeing able to switch polarizations mid-pass has been of huge benefit, \nand you can definitely see a difference in signal strength (depending on \nthe satellite, its antennas, geometry, etc.).\n\nSo generally, I highly recommend the M2 products for this, if you can \nafford it.  I also use the M2 antennas personally, but can't afford the \npolarization switches for myself for my home setup.\n\nIf you are looking for DIY / cheaper alternatives, The ARRL Antenna \nHandbook has some good 'schemes' for polarization switching.  Depending \non how you tackle the problem you may need access to either 75 or 100 \nOhm coax for the phasing (I recommend www.therfc.com for this, he has \nall kinds of cable and may even fabricate some phase aligned ones for \nyou if you ask nicely). Most of those schemes require some type of coax \nrelay, but you might be able to find something relatively cheap on \nebay.  Also, you can find a good article on using Omron PCB relays for \nRF work here, if you would like to attempt to 'build' a coax relay: \nhttps://www.w6pql.com/using_inexpensive_relays.htm.\n\n\nHope this helps! Goodluck!\n\n-Zach, KJ4QLP\n\nResearch Associate\nAerospace Systems Lab\nTed & Karyn Hume Center for National Security & Technology\nVirginia Polytechnic Institute & State University\nWork Phone: 540-231-4174\nCell Phone: 540-808-6305\n\nOn 3/25/2018 9:58 AM, WB8PFZ via AMSAT-BB wrote:\n> M2 sells a driven element assembly that allows polarity switching for there 435 antennas. Has any one used this product and can comment? Is there a cheaper way to do this? Thanks Mike\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions expressed\n> are solely those of the author, and do not reflect the official views of AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n\n",
    "attachments": []
}