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Advice for a 2.5 Ghz antenna placement

 
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alexandru
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PostPosted: Tue Jul 03, 2018 2:11 pm    Post subject: Advice for a 2.5 Ghz antenna placement Reply with quote

I have a circuit demanding a 2.4Ghz antenna inside a metal enclosure.
I cannot place it on the external casing since the case it's movable and will also be exposed to other issues.

I need some advice regarding antenna placement.

I thought about making a horn antenna to drive waves outside through the hole.

But then is the antenna current position right or should be vertical inside the horn (its axis to be perpendicular to horn axis)?

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admin
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PostPosted: Tue Jul 03, 2018 5:41 pm    Post subject: Reply with quote

what are the dimensions of the hole?
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alexandru
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PostPosted: Tue Jul 03, 2018 5:55 pm    Post subject: Reply with quote

    - The hole is about 40 mm in diameter.
    - Antenna is 13 mm tall
    - Distance between wall the antenna is mounted on and exterior metallic wall (center of the hole) is also about 35mm

Current setup works to some degree. I only want to know if and how can I improve it.
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admin
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PostPosted: Tue Jul 03, 2018 9:07 pm    Post subject: Reply with quote

It looks like someone sized the hole precisely for radiation. You should have a dimater of at least a wavelength, and pi*d = 0.125 which is the wavelength of 2.4GHz

I would use vertically polarized antenna as close to the hole as possible

a horn would not work because horns should be several wavelengths in size to be a proper horn, and you don't have that
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alexandru
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PostPosted: Tue Jul 03, 2018 9:24 pm    Post subject: Reply with quote

Thank you for reply.
I did the hole myself so it is only simple coincidence Smile.

1. Now, when you say to be vertically polarized you mean to place it like the picture below?


2. Shall I try by, any means, to create something like a parabola that will reach the hole (such as no radiation could go behind the outern metallic case)?

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admin
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PostPosted: Sat Jul 07, 2018 6:22 pm    Post subject: Reply with quote

you need to be careful backing an antenna iwth metal, you can cause more harm than good. See for instance, http://www.antenna-theory.com/antennas/reflectors/cornerReflector.php
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alexandru
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PostPosted: Sat Jul 07, 2018 6:29 pm    Post subject: Reply with quote

So the antenna position in the first picture of my last post is safer than the second one?

But, please confirm, that by vertical you mean the antenna position in my last post pictures.

Thank you!
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admin
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PostPosted: Mon Jul 09, 2018 9:01 pm    Post subject: Reply with quote

Yes vertical as shown. If the aperture/opening is circular it won't be critical
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