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  • Antenna for nightmare location

    From M. Oi@21:1/5 to All on Mon May 22 14:31:16 2023
    Hi

    I'm looking for an antenna(s) for my location which appears to me to be a nightmare location, because it is a 135 sq.metre, single-storey building
    on a 300sqm plot build on a hardcore float on rock/sand land.

    The plot is completely covered by stamped-concrete. There are two-storey buildings 10-14 metres to the west & south. To the east there is a field to which I have no access. North is public path and a dirt road.

    The apex root is wood with a clay-tile covering, the longest dimension is approx. 20 metres, but has domestic powerline running parallel at a
    distance of 12 metres.

    Until now, I've got by with trips out with small vertical but, due to
    health reasons, I can no longer drive.

    I'd welcome any suggestions for my location.

    TIA

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  • From Allodoxaphobia@21:1/5 to M. Oi on Mon May 22 16:48:09 2023
    On Mon, 22 May 2023 14:31:16 GMT, M. Oi wrote:
    Hi

    I'm looking for an antenna(s) for my location which appears to me to be a nightmare location, because it is a 135 sq.metre, single-storey building
    on a 300sqm plot build on a hardcore float on rock/sand land.

    The plot is completely covered by stamped-concrete. There are two-storey buildings 10-14 metres to the west & south. To the east there is a field to which I have no access. North is public path and a dirt road.

    The apex root is wood with a clay-tile covering, the longest dimension is approx. 20 metres, but has domestic powerline running parallel at a
    distance of 12 metres.

    Until now, I've got by with trips out with small vertical but, due to
    health reasons, I can no longer drive.

    I'd welcome any suggestions for my location.

    Sounds awfful, for sure!
    Unlees you're concerned about privacy issues, pass along your Lat./Lon.
    or 8-digit grid square so we can use Google Satellite View (and/or
    Street View) in chewing over your situation.

    73
    Jonesy
    --
    Marvin L Jones | Marvin | W3DHJ.net | linux
    38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD
    * Killfiling google & XXXXbanter.com: jonz.net/ng.htm

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  • From Jeff Liebermann@21:1/5 to M. Oi on Mon May 22 10:49:45 2023
    On Mon, 22 May 2023 14:31:16 GMT, "M. Oi" <moi@here.now> wrote:

    Hi

    I'm looking for an antenna(s) for my location which appears to me to be a >nightmare location (...)

    Is this for HF, VHF, UHF, satellite, microwave, etc? It would be
    helpful to know what frequencies you plan to use.

    For HF, magnetic loop antennas are small and work well in limited
    locations.
    <https://www.google.com/search?q=magnetic+loop+antenna&tbm=isch>
    There are some limitations to what can be done with a magnetic loop
    antenna. The loop is resonant and very high Q. Therefore, you need
    to retune the loop every time you change frequency. On the lower
    bands, the loop bandwidth can be less than the modulation bandwidth,
    which can be a problem. Any losses in the loop will be converted into
    heat, which will lengthen the aluminum and/or copper parts and change
    the tuning. If you're working split frequency, you'll need to retune
    between transmit and receive. Some loop designs are receive only
    because of high transmit losses. Transmit power is usually limited to
    50 watts max and QRP is usually best.

    There are automatic and remote antenna tuners which will help deal
    with some of these limitations. <https://www.google.com/search?q=magnetic+loop+antenna+tuner&tbm=isch>

    Good luck.

    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

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  • From M. Oi@21:1/5 to All on Mon May 29 17:09:52 2023
    On Mon, 22 May 2023 14:31:16 GMT, M. Oi wrote:

    Many thanks for the suggestions.

    I'm looking at a mag loop, first step will be checking a small home-brew
    QRP loop to check out how useful one might be in my place.

    After searching internet, I find a couple of automatic tuners for such antennas, I could try one of these to overcome tuning difficulties, if i
    decide on that route..

    http://kk5jy.net/AutoCap-v1/ (Arduino based) https://www.instructables.com/Magnetic-Loop-Antenna-Automated-Tuner/ (PIC microntroller)
    https://groups.io/g/SoftwareControlledHamRadio/ (ST32F based - ARRL book Microcontroller Projects for Amateur Radio by W8TEE & AC8GY) https://github.com/Greg-R/magloop_pico_project - Raspberry Pi Pico based
    on W8TEE & AC8GY project.

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  • From Jeff Liebermann@21:1/5 to M. Oi on Mon May 29 20:13:48 2023
    On Mon, 29 May 2023 17:09:52 GMT, "M. Oi" <moi@here.now> wrote:

    On Mon, 22 May 2023 14:31:16 GMT, M. Oi wrote:

    Many thanks for the suggestions.

    I'm looking at a mag loop, first step will be checking a small home-brew
    QRP loop to check out how useful one might be in my place.

    Hint: MEASURE the Q of the finished antenna. <https://www.hamradioschool.com/post/antenna-q-factor>
    If it's much lower than the calculated Q, then you did something wrong
    in the construction. The usual problem is excessively high resistance
    loop resistance and poor tuning capacitor connections or solder
    joints. Note that resistive losses are usually measured in milliohms.

    After searching internet, I find a couple of automatic tuners for such >antennas, I could try one of these to overcome tuning difficulties, if i >decide on that route..

    http://kk5jy.net/AutoCap-v1/ (Arduino based) >https://www.instructables.com/Magnetic-Loop-Antenna-Automated-Tuner/ (PIC >microntroller)
    https://groups.io/g/SoftwareControlledHamRadio/ (ST32F based - ARRL book >Microcontroller Projects for Amateur Radio by W8TEE & AC8GY) >https://github.com/Greg-R/magloop_pico_project - Raspberry Pi Pico based
    on W8TEE & AC8GY project.

    I use these as design guides for magnetic loops: <https://www.aa5tb.com/loop.html> <https://www.aa5tb.com/aa5tb_loop_v1.22f.xlsx>
    more:
    <https://owenduffy.net/blog/?p=1693>
    <https://www.qsl.net/kp4md/magloop.htm> <https://sidstation.loudet.org/antenna-theory-en.xhtml>

    There should be plenty of construction articles scattered around the
    web.

    Good luck.


    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

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