Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Electromagnetic Spectrum: Data Transfer

Electromagnetic Spectrum: Data Transfer

Electromagnetic Spectrum: Data Transfer

The most common frequencies in the spectrum that are used in wireless devices are between 30MHz and 30GHz.  I was wondering  if, data-wise, you have a wireless device that can send data at 30MHz, and one a 30GHz, will the 30GHz device send that data faster?

The 30MHz device should reach that device first, right? (smaller frequency, longer wavelength)

What does frequency mean to data? What does wavelength mean to data? (yes a little redundancy)

Can you give me more info on this and possibly anything else you think might help. I just like to know stuff.

RE: Electromagnetic Spectrum: Data Transfer


Gunnar Englund
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Electromagnetic Spectrum: Data Transfer

Can you give a a website that resembles English more (a lot more). Or can it be translated via google translator?  What is the language?

RE: Electromagnetic Spectrum: Data Transfer

I may have indicated that you need a lot more information before any answer will be meaningful to you.

There is a lot of physics, transmission theory and plain everyday engineering to be mastered before you can benefit from a simple answer here on Eng-Tips.

First. Wireless transmission uses electromagnetic waves. Their speed is independent of wavelength or frequency. And wavelength has nothing to do with "reaching the target" before a signal with an other wavelength. They all get there after the same delay.

Second. Shannon and other guys have done a great deal of research on transmission theory. There is a fundamental relation between carrier frequency and information density time-wise. But different modulation techniques can make a low carrier frequency carry a lot of information - a lot more than one would expect from the fundamental laws.

In the 30 MHz vs 30 GHz case, it is safe to assume that the information sent in a time unit is higher for 30 GHz than for 30 MHz. But the "travelling time" is equal.

Mr Einstein found out about 100 years ago that the speed of an electromagnetic wave is constant (at least in vacuum and almost constant in air) and Mr Maxwell had done the necessary calculation before Einstein formulated his theories, which have then been verified many times during the years.

As you probably know, this site is for exchange of engineering tips. Your question does not quite fit in that category. Thence my "hmm.."

Gunnar Englund
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Electromagnetic Spectrum: Data Transfer

Essentially, the speed of electromagnetic propagation at 30 MHz equals the speed of electromagnetic propagation at 30 GHz. Velocity-of-propagation = C / SQRT(dielectric constant) where C is the speed of light. Vacuum has a dielectric constant of 1. Dry air has a dielectric constant of 1.00001. Don't remember exactly how many zeros are put in front of the 1, but air is just generally taken to be the same as a vacuum.

Also, the propagation distance that can be achieved on the earth is dependent upon frequency. Low frequency signals can travel around the curvature of the earth. High frequency signals are attenuated more by the atmosphere and are line-of-site (fine if you are communicating with a satellite overhead).

Now, the amount of data you put on a signal determines the bandwidth. If you are transmitting a few bits-per-second (i.e. Morse code) your bandwidth will be narrow (a few Hertz wide). Analog voice requires a wider bandwidth (a few Kilo Hz wide).

Data transmission , like WIFI, requires a lot of bandwidth. 802.11 defines 22 MHz wide channels with 5 MHz margin for each channel. Now, if you try to do that at a 30 MHz center frequency, you will find you occupy the spectrum from 19 to 41 MHz, and additionally would require the spectrum from 14 to 46 MHz for any spill-over. You would end up hogging much of the shortwave spectrum. Also since shortwave signals are bounced back by the ionosphere, you might hog much of the shortwave spectrum over a good portion of a continent, and possible portions of the whole earth! A good reason that such data devices are confined to the 2.4GHz and 5 GHz bands - there's room for lots of data channels, the signals are attenuated at a distance, and they're line-of-site.

This is only a few of the issues of what-kind-of-communications is attempted at what-frequency and why.

RE: Electromagnetic Spectrum: Data Transfer

They go the same speed.
It'd be good to do some reading first and ask questions on the technical stuff you didn't understand after many hours of reading. I believe this website rightly requires you to try to find out on your own, via Google etc, then ask questions.

Sorry for the "go do some reading" instructions, but this website mostly has very experienced technical people and it's most common for beginners to "ask for reference books". Google is great to start with though.

good luck,


RE: Electromagnetic Spectrum: Data Transfer

Sorry guys,

 Forgot that the medium that the signal travels through determines the speed, not the wavelength.  Remember hearing that in high school a few years ago smile.

RE: Electromagnetic Spectrum: Data Transfer

The propagation delay of a pulse is dependent on the speed of the EM wave in the media.  Therefore, to the first order, the time to receive the first edge of a signal is nearly independent of wavelength.

However, the total transmission time of a message is dependent on the wavelength, since the information capacity of the channel is limited by the wavelength.  Therefore, a message sent at 30 MHz will take about 1000 time longer to complete transmission than a message sent at 30 GHz, assuming identical coding.


FAQ731-376: Eng-Tips.com Forum Policies

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close