External Links

Here are some useful links that, if you like the way this site is written, you will probably like these as well. Some of them have a strong connection to the Fourier Transform, some of them less so. Antenna Theory.com All types of antennas are classified according to the frequency range they operate in. For instance, low frequency satellite dishes are much different than wifi antennas, which operate over a relatively small distance. The very fundamentals of radio information exchange is based on the idea that messages can be divided into separate frequencies and sent indpendently; as such the whole wireless communications field rests upon the ideas of Fourier in some sense. This site also describes the technicalities of antennas, including VSWR and Smith Charts. Maxwells Equations.com Maxwell's Equations are the fundamental laws that govern all of Electromagnetics, which is the study of Electric and Magnetic Fields. It is well known that the properties of Electromagnetic Waves behave differently at different frequencies - for instance, as far as human scales are concerned, visible light travels in a straight line whereas low frequency radio waves (which are EM waves just like light) experience diffraction and wrap around objects. The Fourier Transform is applied to Maxwell's Equations by simplifying some of the derivatives in the equations. Particularly, if you limit your consideration of the E&M fields to sinusoids of a single frequency (which we know from Fourier Theory that is ok - since all waveforms are the sum of sinusoids), and because Maxwell's Equations are linear - all the time derivatives in Maxwell's Equations can be replaced by i*2*pi*f, which is the time derivative multiplier of a sinusoidal function oscillation at frequency f. Why is the sky blue? Have you ever looked up at the sky and asked yourself why the sky is not red, or black? It's not an easy question to answer. But the sky is blue. Part of the mystery is solved by noting that the white light from the sun can be decomposed into the sum of many different colors of light - blue, red, green, etc. This can be shown with a simple prism that divides light into its rainbow constituents. In some sense, this is exactly a Fourier Transform then - we can see the components that make up the total signal! This site is a good read for understanding one of the best questions of all time. When Does The Time Change?.com This site relates to remembering when the clocks move forward or back in most of the world, for some archaic reason. OK, I'm not entirely sure how exactly this relates to the Fourier Transform. I just have trouble remembering when to spring forward and fall back. So there is an email list you can sign up for to get an email.