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Wow Jeff I was waiting to see if you would chime in on this.?

Kathy Joseph of Kathy Loves Physics YouTube channel does a great talk on this. She is a fascinating?person whom I first became acquainted with as the keynote speaker at last year's PCB Carolina trade show. She wrote a great book titled "The Lightning Tamers" which covers in great detail the history of electricity and the masters thereof.

I highly recommend anyone with an interest?in this watch her videos and buy her book.

See you at the Berryville Hamfest next year!

Sam

Sam Reaves

ARS W3OHM

Electronics and Mechanical Hardware Design Engineering Manager

Staff Scientist Andritz Rolls Global Research Center (RETIRED)

On Fri, Nov 10, 2023 at 10:37?AM Jeff Kruth via <kmec=[email protected]> wrote:

Hello All!

Don't misunderstand me - I am not saying you need to solve field theory math to be able to do microwave work (it is nice though). But, you should understand the basics if you want to be as accurate as possible. Computers can solve the math (do the heavy lifting!) for you now if you can afford the software.
I do a brief review of Maxwell in my Microwave Systems class for the students (who all hate Calc 3 - Vector math, and didn't learn much in Physics II) and my explanation is that there are two source equations and two linkage equations. They provide insight into what is going on: the fact that a time changing E or H field caused by circuit quantities (like current) can give rise to a SPATIALLY distributed vector field of the other quantity. Time changing E gives rise to spatially distributed H, etc. In other words, the magic by which a time changing current in an antenna can make energy "leap out" into space and propagate away to a structure (another antenna) with the correct properties at some distance, inducing a current in that structure.
The source equations just tell you where the energy is coming from (no magnetic monopoles!), and the constituent equations link E & H to D & B thru material properties (permittivity and permeability). The latter is VERY important as it shows how materials effect E-M waves, something we use a lot in our work.
Oliver Heaviside is a much overlooked genius who (IIRC) took Maxwell's almost opaque work of 20 equations in 20 unknowns (very few who read it, sadly, could understand it, even though Maxwell was also a genius)? and reduced it to the familiar 4 equations we call Maxwell's equations today. From about 1890 to the end of the 1920's, we called them the "Maxwell-Heaviside" equations because Heavyside made them accessible to the common practitioner. Albert Einstein was somewhat lazy in his writings and dropped Heavisides name from Maxwell, dooming Heavyside to obscurity. That was OK with the physicists, because they didn't like Heavyside anyway. This was due to Heavyside creating the study of Electrical Engineering ("electricity was too important to leave to the physicists alone") and thus diminishing the involvement of physicists (in their eyes, at least) in this important field. After all,the 19th century WAS the century of electricity!
Heaviside created so much we use - The telegrapher equation for characteristic impedance of transmission lines, coax cable, early studies on the ionosphere (the "Heavyside Layer"), echo cancelling in telephone circuits and so. A great book on his life is from the IEEE press called "Sage in Solitude" and worth a read. He also wrote a (IIRC) three volume set which was a collection of his letters and writings which (as I understand it) is a much more readable explanation of the M-H equations and their implications. Maybe after I retire, I will locate and read these.
If you do want a little deeper understanding of E-M in microwaves, concentrate of boundary conditions - how waves interact when encountering the boundary between two materials. That's where the magic occurs (shorts, opens, losses, phase delay, etc.)
Regards,
Jeff Kruth