What's new for August 2010?

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

The long hot summer is burning out, but we're not! We've added the following content:

• This month we've got three new pages that play together. The first provides a definition of transverse electromagnetic mode (TEM). We tried to pander to the lowest common denominator, so we used Buzz Lightyear to illustrate why microstrip is (usually) not a TEM. And we named two ways that microstrip could provide TEM mode.
• Next up is a page on filling factor. Filling factor is the intermediate calculation that must be done in non-TEM transmission media (such as microstrip or CPW) in order to calculate the effective dielectric constant (Keff) from the substrate material's relative permittivity (ER)
• Then finally, the piece de resistance (or maybe it's just "a piece"?) We now have a page on how to extract the dielectric constant (Dk) and loss factor (Df) of a substrate material based on measurements of transmission lines using a spreadsheet that you can download. This simple technique has never been published before to our knowledge, and we're anxious for some smart people to peer review it.
• Two new rules of thumb have resulted from our discussion of filling factor.
• We're still waiting for entries for our Utterly Monstrous, Mind-Roasting Microwave Design Contest! For the summer of 2010, we'll propose a friendly competition on an utterly useless but interesting design problem: Suppose you wanted to design an RF amplifier operating somewhere north of 100 MHz with at least 10 dB small signal gain in 50 ohms, but all you have available for matching networks is coax cable? How would you hack up some cables to produce a working prototype? Hints: transformers are easy, bypass capacitors and blocking caps might take some thought. We'll allow a few exceptions: you will need something for a ground plane, and one resistor for stabilizing the mess. So pick out your favorite unmatched transistor and get busy. If you have any questions, send them in and we'll supply the answers to all right here. First submission of a realistic "paper design" gets $100, and first submission of photos and measured data of a breadboard also gets $100. Employees of legal firms, Wall Street, BP and right-wing talk show hosts are not eligible! Contest is open until at least one winner is declared, unless we cancel it for lack of interest or it turns out to be completely impossible. Contact us if you want to participate, or have questions or comments.
  

We've got some new questions--and answers--on our Microwave Message Board. We've have hundreds of topics posted on various microwave engineering subjects, with many more replies; our message board is an industry resource. Post your own questions, or help us answer some of the ones that are already posted. Some of the posted material may eventually get captured in our encyclopedia, so do your part for posterity! We'll remove any postings that we consider inappropriate.

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