As is always the case, we've been busy adding plenty of new stuff to Microwaves101. We ain't been slack, Cap'n Walker!

New for February 2021: Looks like Harriet Tubman may be heading back onto the twenty dollar bill, after the previous administration scuttled the plan four years ago to please all of our new-found "patriots".  Seems kind of crazy that a person that paid only $750 in taxes should have any say at all on what goes on our money... Here's a site with some interesting photos having to do with Ms. Tubman, for your Black History Month review. Did you know her name was honored on a WWII Liberty Ship?

Meanwhile, what's new at Microwaves101?

  • Bedford Automated Artwork was a computer-added design tool for generating artwork for stripline and microstrip circuits. Developed by the Missile Systems Division of Raytheon Company, it was presented at the 1982 IEEE IMS. Our new "BAA" page also somewhat describes what it was like to work at the Bedford plant, circa 1982.  Prediction: someone from Hughes, Texas Instruments, Westinghouse, etc. is going to email us and say "we had that capability years earlier".   The first person to prove that claim will be eligible for a free Microwaves101 coffee mug!

  • Rubylithography (or just "rubylith" for short) now has a well-deserved page in our history section. This technique is how your grandparents created microstrip and stripline artwork in the "mod" 60s and  "apathetic" '70s. If Skylab contained any microstrip hardware, we can't prove it was made using rubylith, because it burned up in re-entry in 1979!

  • In our Microwaves101 slang dictionary, we've added mouse bites and rat's nest

  • On our portmanteaux in engineering page, we've added filtercon, the filtered connector.

  • Magical Lambda is a new  page by Sumadhura Gunupati, a student of Dr. Raghavan at National Institute of Technology Trichy. Here you can see the many aspects of microwave engineering that can be expressed in terms of wavelength (lambda). Bravo!

  • In addition, three other NITT students provided content to our site this month.  You can access these works from the NITT page of just click the following links.  Alok TJ presents A 3-D Wheelers Curve.  The Wheeler’s curve calculates microstrip impedance from parameters w/h (width divided by height) and dielectric constant.  It is plotted by merging two curves from either side of the point of discontinuity where w/h=1, and then plotting on one graph for complete range of (w/h) values. From the Wheeler’s Curve Plot, corresponding values of Impedance and (w/h) on the curve is taken with uniform linear separation and made into a tabular column for each standard dielectric substrate. All the values obtained from the Wheeler’s curve are consolidated in a single chart for Microstrip line designers, and presented (for the first time that we know of!) as a 3D surface plot.

  • RS Anju sent us some coplanar waveguide characteristic curves, helpful in determining the width and spacing for any dielectric at any frequency. You may also want to download the python code used to create these plots

  • A Windows application that designs Stepped-Impedance Low Pass Filters using Python was contributed by Debrup Mukherjee. This paper describes how to create your own application that takes the filter specifications as input and designs the complete layout by itself. All we need to have is a good understanding of how microwave filters work and what are the steps taken by an experienced designer to design the layout. The way an experienced designer designs filters, the same way the process can be automated and make a computer do all the calculations and all the hard work for us. The software, that we will learn to write in this page takes care of everything and gives us the complete layout with all the dimensions.

  • Our new SSB transmission page provided a home for our featured video for January 2021. This video was produced by Bell Labs, back in the day when studying some aspects of science was a prerequisite for graduating high school. Today, no one is likely going to link to that movie from their Facebook page.

  • We're always fixing typos and making fixes of one kind or another. In the past month we did a little maintenance on our mortuary archives, and made a few more changes to the discussion board. We also fixed some links on our sheet resistance page, and uploaded a better graphic and some new data on the March coupler page. Notice something not-quite-right? Let us know!

  • Meanwhile, on our discussion board, we've got some questions that need YOUR answers. Jim is looking for a source of silver-plated screws for tuning waveguide. Here's some musings on what happens to a self-biased amplifier during large-signal operation.  Bob is looking for advice on a YIG detection system.  What about field phases in quasi-TEM media of two different dielectric materials? People are still talking about how they document their designs: the latest answer tells you why OneDrive is not a great backup plan.  Pop on over to the discussion board to register and sign in, then chime in on existing threads, or start your own topics. Our new user approval process is quick and anonymous, blocks most bots, and eliminates spam by more than 99%. At least that's what the sales rep told us...

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