[EE] I thought this was rather interesting

[Van Horn, David]

A lot of what I work on these days is inside the radiansphere, where things don’t work like they do in the far field.

http://aetherczar.com/

The volume on these is very low, but well worth the effort.

Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
email: ***@backcountryaccess.com<mailto:***@backcountryaccess.com>

[Sean Breheny]

I must say that I've never heard the term "radiansphere" before and I had
to look it up. Interesting indeed!

On Mon, Jun 18, 2018 at 10:24 AM, Van Horn, David <

Post by Van Horn, David
A lot of what I work on these days is inside the radiansphere, where
things don’t work like they do in the far field.
http://aetherczar.com/
The volume on these is very low, but well worth the effort.
http://youtu.be/_lKgSOt-ras
http://youtu.be/hWmYzJyouyE
http://youtu.be/tQreHssk1Ms
http://youtu.be/AaPfm_80URA
Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
backcountryaccess.com>
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[David C Brown]

Is it what we old time engineers call the "near field"?

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by Sean Breheny
I must say that I've never heard the term "radiansphere" before and I had
to look it up. Interesting indeed!
On Mon, Jun 18, 2018 at 10:24 AM, Van Horn, David <

Post by Van Horn, David
A lot of what I work on these days is inside the radiansphere, where
things don’t work like they do in the far field.
http://aetherczar.com/
The volume on these is very low, but well worth the effort.
http://youtu.be/_lKgSOt-ras
http://youtu.be/hWmYzJyouyE
http://youtu.be/tQreHssk1Ms
http://youtu.be/AaPfm_80URA
Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
backcountryaccess.com>
--
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View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

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[Van Horn, David]

Yup. He covers the definitions of "near field" and there are a bunch.


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of David C Brown
Sent: Monday, June 18, 2018 10:18 AM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] I thought this was rather interesting

Is it what we old time engineers call the "near field"?

__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
Derbyshire eMail: ***@gmail.com
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*

Post by Sean Breheny
I must say that I've never heard the term "radiansphere" before and I
had to look it up. Interesting indeed!
On Mon, Jun 18, 2018 at 10:24 AM, Van Horn, David <

Post by Van Horn, David
A lot of what I work on these days is inside the radiansphere, where
things don’t work like they do in the far field.
http://aetherczar.com/
The volume on these is very low, but well worth the effort.
http://youtu.be/_lKgSOt-ras
http://youtu.be/hWmYzJyouyE
http://youtu.be/tQreHssk1Ms
http://youtu.be/AaPfm_80URA
Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
backcountryaccess.com>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

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[Sean Breheny]

Yes, but the surprising thing (to me) is that it is not a new term. It
seems to have been coined in 1959:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6909&rep=rep1&type=pdf

To me, the idea of close vs far from an antenna really has two parts - one
of them is whether you are far enough away that the radiation looks like a
plane wave in free space (so there is a strict ratio between electric and
magnetic field magnitudes) and the other is when the radiation pattern of
the antenna stops being a function of distance (Fresnel vs Fraunhoffer
regimes). For the case where the antenna is much larger than a wavelength,
the former can be at a much shorter distance than the latter.

Post by David C Brown
Is it what we old time engineers call the "near field"?
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by Sean Breheny
I must say that I've never heard the term "radiansphere" before and I had
to look it up. Interesting indeed!
On Mon, Jun 18, 2018 at 10:24 AM, Van Horn, David <

Post by Van Horn, David
A lot of what I work on these days is inside the radiansphere, where
things don’t work like they do in the far field.
http://aetherczar.com/
The volume on these is very low, but well worth the effort.
http://youtu.be/_lKgSOt-ras
http://youtu.be/hWmYzJyouyE
http://youtu.be/tQreHssk1Ms
http://youtu.be/AaPfm_80URA
Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
backcountryaccess.com>
--
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[Van Horn, David]

These days, I'm working at 457kHz with ferrite bar antennas that are essentially a point with regards to wavelength, and at distances far less than a wavelength.

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Sean Breheny
Sent: Monday, June 18, 2018 10:25 AM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] I thought this was rather interesting

Yes, but the surprising thing (to me) is that it is not a new term. It seems to have been coined in 1959:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6909&rep=rep1&type=pdf

To me, the idea of close vs far from an antenna really has two parts - one of them is whether you are far enough away that the radiation looks like a plane wave in free space (so there is a strict ratio between electric and magnetic field magnitudes) and the other is when the radiation pattern of the antenna stops being a function of distance (Fresnel vs Fraunhoffer regimes). For the case where the antenna is much larger than a wavelength, the former can be at a much shorter distance than the latter.

Post by David C Brown
Is it what we old time engineers call the "near field"?
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak Phone: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*

Post by Sean Breheny
I must say that I've never heard the term "radiansphere" before and
I had to look it up. Interesting indeed!
On Mon, Jun 18, 2018 at 10:24 AM, Van Horn, David <

Post by Van Horn, David
A lot of what I work on these days is inside the radiansphere,
where things don’t work like they do in the far field.
http://aetherczar.com/
The volume on these is very low, but well worth the effort.
http://youtu.be/_lKgSOt-ras
http://youtu.be/hWmYzJyouyE
http://youtu.be/tQreHssk1Ms
http://youtu.be/AaPfm_80URA
Not all the fun is up in the GHz. 😊
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: [phone] x110
backcountryaccess.com>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
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[RussellMc]

Post by Sean Breheny
I must say that I've never heard the term "radiansphere" before and I had
to look it up. Interesting indeed!

​Meaning obviousish in the context BUT I'd never heard it!

Nor has Gargoyle's NGrams system!​

Garglabet

https://www.google.co.nz/search?num=50&source=hp&ei=OKcoW7v4D8bM0gTmt6noDQ&q=radiansphere&oq=radiansphere&gs_l=psy-ab.3..0i13k1j0i10i30k1.2501.5576.0.6487.13.12.0.0.0.0.256.2413.2-11.11.0....0...1c.1.64.psy-ab..2.11.2411.0..0j35i39k1j0i131k1.0.4IlRSXbBCpg

Images

https://www.google.co.nz/search?q=radiansphere&num=50&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwigjoGQkd_bAhXCqJQKHbsaA3UQsAQIZg&biw=1680&bih=917


R