What is the more penetration into the objects, low frequency

sound penetration frequency range

What is the more penetration into the objects, low frequency or the high frequency. If low frequency, why its not used for communication through ionospher

Hi...
As per Planck's Law...E=hv
where h is Planck's constant, v is the frequency and E is energy...
Thus higher the frequency, higher the energy...and higher energy has more penetration power...
Hence higher frequency is more used for communication as compared to lower frequency...
That is also the reason for FM (higher frequency) passing through the ionosphere and AM (lower frequency) being reflected from ionosphere...

The lower frequency has more penertration because it has larger wave length and more diffraction than higher frequency. The reason why high frequency is always used is that protability is required for handsets which limit the length of anntena, whose length is proportional to the wave length of the radio.

Re: What is the more penetration into the objects, low frequ

carpa
Yes it is true...that lower frequencies have more diffraction due to higher wavelengths....
BUT
diffractiondoes not mean penetration...only bending around corners...and in an urban area...where line of sight is obstructed...diffraction does not cover all area...however...penetration does..

Re: What is the more penetration into the objects, low frequ

Hi, Lower frequency has higher penetration (look at submarines they use 10 - 50 KHz freqcency for communication since it is the only thing that can communicate underwater).

But its not all that simple in cities, enviromental noice can also be a limiting factor. Noice at low frequencies tend to be higher due to monitors, electric motors, wheather, ect. The best is to have small cells with a limited range but high bandwidth, that is why they have cells that are sometimes 250 meters and can handle 64 calls at the same time.

regards,

Paul.

Re: What is the more penetration into the objects, low frequ

The fact that submarines use low frequency does not
have anything to do with penetration. Underwater the
only effective way to communicate is audio. That is the
way whales and dolphins communicate.
10-50 KHz are audio not radiowaves.

For other hand, in wireless NLOS the main mechanism for
propagation is difraccion not penetration. penetration
can loss has much as 40 dB per meter, while difraction
can have 10~20 dB per obstruction.

Re: What is the more penetration into the objects, low frequ

jallem before you open your mouth next time do read something please !.

https://en.wikipedia.org/wiki/Communications_with_submarines
https://en.wikipedia.org/wiki/Very_low_frequency

And dolphins use a completely different way of communicating compared to whales. Dophins use the same methode as Bat's do (Chirp). whales use ELF (audio waves) not confused with ELF that sub's do use.


Your story about NLOS does also not have anything correct. It is completely depending on frequency and your 40dB/m is just a big joke !!!. A thick forrest is about 60dB/km at 200 - 400 MHz !.

Paul.

Re: What is the more penetration into the objects, low frequ

I think you are the one who has a BIG MOUTH, as big as your ignorance.
Moderator please, take notes of the insult.

In your reference :
"Because electromagnetic radiation such as normal radio communication cannot
travel through thick conductors such as salt water, communication with submarines when they
are submerged is a difficult technological task which requires specific techniques and devices."

You see, under water there is not radio communication. Electromagnetic radiation
is not possible under water. Acoustic, VLF and ELF all are very LOW frequency, got it?
Even sub-audio........There is not penetration. The mechanism is trough sound.
That is what I meant by Dolphins and Whales, they transmit sound in very low
frequency, and again that is not RF and that is not RF penetration.

Material can be clasified as dielectric or conductor. And in both of them the propa
gation losses are very high. The RF "DOES NOT TRAVEL TROUGH". The RF travel
around, by difraction.

In a wood there is not penetration since the woods are not homo
geneous, there is air between them, so the RF wave travel trough them.
There is a stupid believe among people that there is penetration and you are
one of them.

Get a book about propagation, and stop insulting others.

MODERATOR TAKE NOTE "HE INSULTED ME".

Added after 2 hours 42 minutes:

Quote:

The mechanism behind electromagnetic wave propagation are diverse,
but can generally be attributed to REFLECTION, DIFFRACTION and SCATTERING.

Read Chapter 3, section 3.1, pp. 69 to 74 of Rappaport, "Wireless
Communication", Prentice Hall.

Paul Holland: The next time you open your big mouth try to not to insult.

Re: What is the more penetration into the objects, low frequ

I did not insult you, you did it yourself and now your calling for mamma. Hope communication is not your profession like mine but something different.

You did say: Electromagnetic radiation
is not possible under water

I proof:
http://www.fas.org/nuke/guide/usa/c3i/elf.htm

http://www.vlf.it/submarine/sbmarine.html

82Hz ELF ELECTROMAGNETIC WAVES !!!! go to the bottom of the sea !!!!!!!!!

http://en.wikipedia.org/wiki/Very_low_frequency

Maybe these antenna's look like loadspeakers to you but for me they are electromagnetic antenna's for submarine communications.

I also do not see any proof for 40dB/m attenuation friend.

You did say:
In a wood there is not penetration since the woods are not homo
geneous, there is air between them, so the RF wave travel trough them.
There is a stupid believe among people that there is penetration and you are
one of them.

I say: I never told you that in a forrest there is penetration is simply told you what the normelized attenuation is for a thick forrest according to ITU at a specific frequency range (maybe you did hear about them !).
I told in an early e-mail that all is depending on frequency what the main mean of propagation is. And in general: that was the question: low frequency have a higher penetration in matter, like sea water, ground, etc.

BTW: According to your text radio waves go through the air . Do you really think that ?. Try it a 60GHz see what happens then


Paul.

Re: What is the more penetration into the objects, low frequ

Hi

This is a very interesting topic and perhaps not well known to most people the differences between how animals communicate and communication nwetwork for submarines.

Please keep this topic free from insults and miscredit each other, I do not judge any one here but stop it. Stick to the facts, if no improvement I clean the topic.

Cl

Re: What is the more penetration into the objects, low frequ

PaulHolland,

Yes you insulted me. But most important you insulted the poster.
But the biggest insult is you IGNORANCE. And that combined with
ARROGANCE is doubly insulting.

Do not call me friend, I am not friend of stupid arrogant like you.

You said you are Communications Specialist? Where did you get that
title? ....from Internet?....All your references are from Internet, that is
right......GET EDUCATION...GO TO SCHOOL.....then and only then
can you be allow to talk about RF. arrogant dutch!!!!!!

MODERATOR: now you can close the post.

my vote with jallem
underwater comm is acoustic wave comm in elf range...and not electromagnetic range...
and as far as internet proof is concerned....it is the most unauthentic source that one can think of...
But hey guys...
take a chill pill...keep it cool

Added after 41 seconds:

my vote with jallem
underwater comm is acoustic wave comm in elf range...and not electromagnetic range...
and as far as internet proof is concerned....it is the most unauthentic source that one can think of...
But hey guys...
take a chill pill...keep it cool
nobody needs to prove his authority over anyone...

Re: What is the more penetration into the objects, low frequ

anwer_sbh: Have a look at the links I provided and simply ignore the previous messages. Go to the stanford link below and simply start reading. A lot of information about ELF/VLF and even ULF penetrating water.

ELF/VLF/LF will not pass ionosphere for this you need to be above the MUF (Maximum Usable Frequency) a term used in HF communication, all frequencies below MUF will be reflected by the ionosphere. MUF is depending on time of day/month, sun spot number (solar activity with an 11 year cycle). The higher you go in frequency the higher the losses will be (Pathloss). For MUF: http://www.spacew.com/www/realtime.php (www.spacew.com)

Also read the ionospheric heating by VLF and HF radio waves : http://www.haarp.alaska.edu/

**broken link removed**

A lot of thesis that have been written in the last years about this topic.

Paul.

PS: For the others: Its a pitty you do not know the famous Grimeton VLF transmitter in Varberg in Sweden. It was built in 1923 and has the only workable machine transmitter in the world. Its now declaired World Cultural Heritage by UNESCO like The Great Pyramid of Giza.