FS: Software for creating elliptic stripline filters

[nctnico]

I'd like to introduce a neat tool for creating elliptic stripline filters I have developed and offer for sale for a very reasonable price.

A bit of background: For a different project I needed several RF low-pass filters. Since one of the filters needed a cut-off frequency close to 2GHz I thought it would be best to use a stripline filter because the component values would become very small. I wanted to use an elliptic filter because these type of filters ofter a very sharp roll off and I could compensate for the pass band ripple anyway. I have searched the internet quite extensively but I could not really find a piece of software or a recipe on how to tackle creating such a filter using striplines. In the end I found a book which had some formulas but those quickly turned into a bunch of messy equations. In order to solve the equations I ended up writing a piece of software. Since I was already busy I wrapped it in a nice GUI and decided to turn it into a product. I hope it will take away some of the black magic and inspire others to enter the RF world.

The software (called Stripline Filter Tool) and the manual can be downloaded from here:
http://www.nctdev.nl/shop_prod.php?pg=17
If the software isn't licensed it works in demo mode.

The picture below shows the example filters I have created using my software:

[KJDS]

There's already a number of software tools around for the job, most notably the add ons to microwave office and ADS, though they are expensive.

How much difference between theory and practice are you seeing?

[nctnico]

I've tested the two filters from the photo and they are pretty close to simulated results from Sonnet Lite (the free version). The top one is about spot on, the bottom one suffers from manufacturing tolerances which caused the cut-off frequency to shift up a bit.  I have included the results in the manual. I have created and simulated several other filters and they all turn out fine in the simulation.