Antenna

Navarra87RF · Posted: Tue Mar 05, 2019 4:19 pm Post subject: Dipole antenna in a liquid

Hello All,

I want to design a dipole submerged in a liquid. How that affects my design in comparison to free space?
Could you point out where I can find info regarding this design?

Thanks for your time and help!
Best,

admin · Site Admin Joined: 03 Jan 2007 Posts: 247

What type of liquid?

Water and especially salt water absorb rf energy.

You need to look up the dielectric constant of the liquid which determines how much shorter the antenna should be. Pretty simple

Navarra87RF · Posted: Thu Mar 07, 2019 10:54 am Post subject:

Thanks for your reply!

Yes, "salt water" trying to replicate the human body's conditions. OK.
Will the liquid's Er affect also a lambda/4 balun?

Thanks again!
Best,

admin · Site Admin Joined: 03 Jan 2007 Posts: 247

If the salt water surrounds the conductors of the balun, yes it will affect the size

Navarra87RF · Posted: Wed Mar 13, 2019 3:55 pm Post subject:

Thanks!

I will try to fabricate the lambda/2 dipole with a folded balun.
How can I calculate the distance between the coax cable and the lambda/4 balun?

[img]http://www.antenna-theory.com/definitions/foldedbalun.jpg[/img]

Best,

chaicustard · Antenna-Theory.com Newbie Joined: 23 Feb 2010 Posts: 5

Lambda in water could be up to 1/10th that of that in air.
https://en.wikipedia.org/wiki/Relative_permittivity
https://www.allaboutcircuits.com/tools/wavelength-tem-calculator/

Everything is scaled smaller, and its dependant on frequency ( esp above 1 GHz) . I doubt you can reliably scale any air-antenna without some modelling software.

Instead of thinking in radiating-antenna terms, you could treat the liquid as an energy-absorbing media, since the energy loss is far more in resistive heating loss, rather than a propogating electromagnetic field.

It depends on what youre actually trying to acheive in this design.

geadinc · Posted: Fri Apr 19, 2019 12:05 am Post subject:

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