Antennas, Feedlines, Towers & Rotors

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Help me understand magloop vs. G5rv jr. noise difference (pt. II)

Posted: 29 Jan 2019 12:28 AM PST
https://forums.qrz.com/index.php?thr...-pt-ii.644360/



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Phasing

Posted: 29 Jan 2019 12:19 AM PST
https://forums.qrz.com/index.php?thr...hasing.640933/



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Help me understand the noise difference between Magloop vs. G5RV jr. At QTH.

Posted: 28 Jan 2019 10:02 PM PST
https://forums.qrz.com/index.php?thr...at-qth.642866/



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Tried stealth loop antenna, now what?

Posted: 28 Jan 2019 09:11 PM PST
https://forums.qrz.com/index.php?thr...w-what.644354/



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Ok, is this true?

Posted: 28 Jan 2019 07:41 PM PST
https://forums.qrz.com/index.php?thr...s-true.643423/



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Anyone using a Razer made buy Rt Innovations

Posted: 28 Jan 2019 06:30 PM PST
https://forums.qrz.com/index.php?thr...ations.616070/



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50 Ohm, 0.38% wavelength, Vertical Loop for the HF Bands

Posted: 28 Jan 2019 02:19 PM PST
https://forums.qrz.com/index.php?thr...-bands.644315/

On 1/29/19 5:38 AM, QRZ.com via rec.radio.amateur.moderated Admin wrote:

Hello, and I just can seem to find anything on "magloop" antennas in any
of my non-ham antenna theory and design textbooks (e.g. Jasik, Terman,
King & Harrison, etc). Just shielded and unshielded loops, electrically
small or large. Don't see anything on "elecloops" either . Could hams
possibly know something these other authors don't? Sincerely, and 73s
from N4GGO,

--
J. B. Wood e-mail:

On 1/29/19 5:38 AM, QRZ.com via rec.radio.amateur.moderated Admin wrote:

Hello, and I just can seem to find anything on "magloop" antennas in any
of my non-ham antenna theory and design textbooks (e.g. Jasik, Terman,
King & Harrison, etc). Just shielded and unshielded loops, electrically
small or large. Don't see anything on "elecloops" either . Could
hams possibly know something these other authors don't? Sincerely, and
73s from N4GGO,

--
J. B. Wood e-mail:

On Tue, 29 Jan 2019 13:20:40 EST, "J.B. Wood"
wrote:

On 1/29/19 5:38 AM, QRZ.com via rec.radio.amateur.moderated Admin wrote:

Hello, and I just can seem to find anything on "magloop" antennas in any
of my non-ham antenna theory and design textbooks (e.g. Jasik, Terman,
King & Harrison, etc). Just shielded and unshielded loops, electrically
small or large. Don't see anything on "elecloops" either . Could
hams possibly know something these other authors don't? Sincerely, and
73s from N4GGO,

Look for "small loop antenna" or "small receiving loop antenna". That
seems to be the official names for these loops. Somewhere on the web
is Owen Duffy's rant on the topic of naming loop antenna, but I can't
find it.
https://owenduffy.net/blog/?s=small+receiving+loop+antenna
https://owenduffy.net/blog/?s=magnetic+loop

Digging through "Antennas" by John Kraus (1950), I found mention of
small loops in Chapter 6 "The Loop Antenna".

King and Harrison has this on loop antennas:
https://link.springer.com/chapter/10.1007/978-1-4684-6081-0_4

In "Antenna Engineering Handbook" by Henry Jasik (1961), this is all
of 4 pages in Chapter 6 on loop antennas with no mention of small
loops, magnetic loops, or high-Q designs. Most of my other books
concentrate on low Q HF antennas and direction finding configurations.

Since all the books that you and I have mentioned are from the 1950's
and 60's, and well before small magnetic loop antenna became popular,
I suspect the absence of detailed models and studies are
understandable. Also, the magnetic loop antenna is rather impractical
for anything other than amateur radio use because of the need to
retune the antenna with even the slightest change in frequency. With
commercial use limited or non-existent, I wouldn't expect to see much
funded research into their characteristics.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 1/29/19 5:47 PM, Jeff Liebermann wrote:

Since all the books that you and I have mentioned are from the 1950's
and 60's, and well before small magnetic loop antenna became popular,
I suspect the absence of detailed models and studies are
understandable. Also, the magnetic loop antenna is rather impractical
for anything other than amateur radio use because of the need to
retune the antenna with even the slightest change in frequency. With
commercial use limited or non-existent, I wouldn't expect to see much
funded research into their characteristics.



Hello, and theory (established via experiments with repeatable results)
and applied math don't change, regardless of the decade. The point here
is that AFAIK only hams use the adjective "magnetic" to describe some
sort of property that the antennas covered in those textbooks don't
engender. I've posted before on this subject. The term "magnetic" adds
nothing to describing the geometry or operation of a loop antenna. And
it can add to the confusion if it implies there are additional types of
loops ("electric loops"?) or that a magnet is a component of the antenna.

My own take on all this is that it got started since a closed loop/coil
of wire will experience an induced current when in the presence of a
time-varying magnetic field. No problem here. This is a close-in
(non-radiating) condition such as we would have with coupled loops/coils
inside a power transformer. The RF equivalent would be a having a loop
or straight wire in the near (induction) field of a transmitting antenna.

Now assume that coil/loop is in the radiating (far) field of a
transmitter and performing as a receiving antenna. A distance of several
wavelengths or more will ensure that. In that scenario the loop is
responding to a propagating electromagnetic (EM) field. So is the loop
responding to the magnetic (H) or electric (E) field of an EM wave?
Despite what some folks believe, EM theory says you can't have a
propagating E field without an H field component or vice-versa.
Sincerely, and 73s from N4GGO,

--
J. B. Wood e-mail:

On 1/29/19 5:47 PM, Jeff Liebermann wrote:

Since all the books that you and I have mentioned are from the 1950's
and 60's, and well before small magnetic loop antenna became popular,
I suspect the absence of detailed models and studies are
understandable. Also, the magnetic loop antenna is rather impractical
for anything other than amateur radio use because of the need to
retune the antenna with even the slightest change in frequency. With
commercial use limited or non-existent, I wouldn't expect to see much
funded research into their characteristics.



Hello, and theory (established via experiments with repeatable results)
and applied math don't change, regardless of the decade. The point here
is that AFAIK only hams use the adjective "magnetic" to describe some
sort of property that the antennas covered in those textbooks don't
engender. I've posted before on this subject. The term "magnetic" adds
nothing to describing the geometry or operation of a loop antenna. And
it can add to the confusion if it implies there are additional types of
loops ("electric loops"?) or that a magnet is a component of the antenna.

My own take on all this is that it got started since a closed loop/coil
of wire will experience an induced current when in the presence of a
time-varying magnetic field. No problem here. This is a close-in
(non-radiating) condition such as we would have with coupled loops/coils
inside a power transformer. The RF equivalent would be a having a loop
or straight wire in the near (induction) field of a transmitting antenna.

Now assume that coil/loop is in the radiating (far) field of a
transmitter and performing as a receiving antenna. A distance of
several wavelengths or more will ensure that. In that scenario the loop
is responding to a propagating electromagnetic (EM) field. So is the
loop responding to the magnetic (H) or electric (E) field of an EM wave?
Despite what some folks believe, EM theory says you can't have a
propagating E field without an H field component or vice-versa.
Sincerely, and 73s from N4GGO,

--
J. B. Wood e-mail: