Microstrip formula for non-standard geometry

-- Mark

Hello Mark,

This is good one (I found it via google also). You can enter both metallics and dielectrics as you want. It would be very nice when you can mail me a Windows Build (I hope it is not that big). A link would also be useful.

My address is valid when you remove abc.

Best regards and thanks,

Wim PA3DJS

AFAIK dielectric between the strip and GP is the most significant unless stripline is to couple to other stuff. Anytime you change board material there are subtle changes in VF. For proto, I always like to allow for trimming where it has to be critical, but best to make it less critical so you don't have to spend time on every board. Air is better, but spacing variations come into play, and what will happen if you drop it. The calculations only get you so far unless you have your constants handy.

This is a bit off topic in direct relation to your post; however, I built this antenna as an external to my wifi router/switch to increase coverage of the net:

Fig. 1-5 and the plot of the radiation pattern (fig. 1-7) I found particularly interesting ...

Regards, JS

Drifting further off topic.... Here's the commercial incantation of that antenna (the three photos on the right) from Tecom:

PCB losses make it a rather marginal performer.

Note the added decoupling sleeve. That somewhat beam uptilt due to the effects of the mounting hardware.

The worst part of the design is that 1/2 the RF is radiated in the first half wave (bottom two elements). 1/4th is radiated from the next half wave. 1/8th from the next dipole, and so on. By the time what's left gets to the top element, there's not much left. With all the RF coming from the base of the antenna, and with the uptilt problem, it's often best to mount the antenna in an inverted position.

I have an NEC2 model somewhere but it has problems. Sorry.

However, I do agree with the article's conclusions. It is a cheap antenna to build.

As for the original question, ATLC is certainly the right answer for modeling a rather unusual microstrip configuration. The program can allegedly be built using Cygwin for Windoze. I haven't tried it:

Note the spelling of Windoze on that page. I looked through the ported package list, but didn't find ATLC.

I will keep this on the web site for a few days. About 3MB download.

This version has problems with muliple dielectrics. I works fine with two dielectrics, air and one of your choosing.

-- Mark

Thanks for sharing this, Mark. I'll try it out as well, just not right now.

Hello Mark,

I received a windows build via Tom and created a .bmp file with the structure (with MSPaint, save as .bmp, not .jpg). Result is OK (I use Win2000 SP4). My hand calculation closely matches the simulated result.

As long as ground (green color) surrounds your structure completely, results are OK. If not (for example a real microstrip line), results are unreliable.

I will make the line and check the VSWR with 50 Ohms termination.

Best regards,

Wim PA3DJS

The version I have, which I sent to Wim, is 4.6.0. I'm not sure about the differences, but if anyone is interested, I have it in a zip file I can send. The zip file is encrypted, so it will pass through at least some of the email filters that take out executables or zips with embedded executables; I'll supply the password of course (just my call...).

Cheers, Tom

download.http://qrkwiggles.googlepages.com/atlc-4.4.4_Win32.zip

Where did you get the Windows build from? My work colleague was the last one to supply Dr. Kirkby a windows build which was ver 4.4.4. It would be great if you could give Dr. Kirkby the latest windows build so he can post it.

-- Mark

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tp://qrkwiggles.googlepages.com/atlc-4.4.4_Win32.zip

Ah, OK; I thought from the atlc website that we'd just all be on our own to do it. I'm an analog guy; I enlisted the help of a digital/ software friend. He had no trouble building it to run in a DOS shell. I'll drop David a note, letting him know that I have it, to see if he'd like it there.

Cheers, Tom

I'm just downloading mdtl from sourceforge, will give it a try as soon as I find some free time. Cool link, thanks for some detective work :)