Antenna for nightmare location

[M. Oi]

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

[Allodoxaphobia]

Post by M. Oi
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

[Jeff Liebermann]

Post by M. Oi
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.

[M. Oi]

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.

[Jeff Liebermann]

Post by M. Oi
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.

Post by M. Oi
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.