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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/PARHNKKNINTUIX7EAYYG7243JY3YXPVD/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "PARHNKKNINTUIX7EAYYG7243JY3YXPVD",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/IEBVFI3OXF6552GSZZ24A2EWJ5B62A4I/",
    "sender": {
        "address": "whattwood (a) gmail.com",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Bill Attwood",
    "subject": "Re: [amsat-bb] CP vs. LP and all that implies",
    "date": "2015-01-22T16:40:23Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BS6HOGSWL52QFPTW376JKJZOWGZZPSWE/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Wow, great post Daniel!  That answers a bunch of questions I had myself \n- I was thinking RHCP would receive better than a H/V combination but it \nlooks like that is not the case.\n\n73,\nBill VE6WK\n\n\nOn 1/22/2015 3:29 AM, Daniel Cussen wrote:\n> Best info on-line I found here:\n>\n> http://sv1bsx.50webs.com/antenna-pol/polarization.html\n>\n> Note the losses of having the wrong circular polarisation from a\n> polarised source are very high. In the real world the antenna may not\n> be perfectly polarised on one end, so difference may not be as great.\n>\n> One very useful/recommended setup for circular is school contacts on 2\n> metres with the space station. It is recommended to be able to switch\n> polarisation in the middle of a school contact as sometimes the signal\n> is not direct but reflected off a solar panel. In this case you may\n> need to suddenly switch polarisation.\n>\n> I have a wimo 2m 6 element X circular antenna with the switching kit.\n> The antenna is extremely light and designed to be mounted at the very\n> rear, to prevent the boom interfering in the signal. I was not that\n> impressed by the elements strength, guessing a bird might be able to\n> bend them by landing on them. The driven element is made from a few\n> parts screwed together. I worry corrosion would quickly make it\n> unreliable. Being limited to 6 elements and quite short a longer\n> linear model may work nearly as good.\n>\n> http://www.wimo.de/xquad-antennas_e.html\n>\n> also:\n>\n> http://www.wimo.de/power-splitter-combiner_e.html#18038\n>\n> The 70cm model I have heard is much better in that the driven element\n> is stamped rather than assembled so less joins to corrode. Also being\n> smaller the elements are stronger.\n>\n> The switch box is designed to be mounted on the mast near the antenna\n> meaning only one coax cable per band needs to be ran out, but then you\n> need DC multicore to switch polarisations. You can select V, H, LHCP,\n> RHCP. One downside is that they do not give the option of a control\n> box, so you need to build one by hand. You need to ensure you do not\n> transmit while switching.\n>\n> All in all it is quite expensive, complicated and messy. Unless you\n> had an inferior setup, and found it lacking I probably would not\n> bother. You only lose 3dB using linear when the source is true\n> circular, so probably not really worth it unless you have maxed out on\n> antenna gain/ receive pre-amps. There are additional losses with\n> switches connectors etc.\n>\n> I have never seen/used the M2 setup so I cannot comment on this. They\n> definitely seem to have more elements as a possibility.\n>\n> At least with the switching option you can compare the signal on\n> different polarisations to see if it does help in the real world. You\n> could always try it on one band, then apply it to both bands if you\n> get a big difference.\n>\n> What do others think?\n>\n> Dan EI9FHB\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://amsat.org/mailman/listinfo/amsat-bb\n\n\n\n---\nThis email has been checked for viruses by Avast antivirus software.\nhttp://www.avast.com\n",
    "attachments": []
}