A few weeks ago we announced our second major release, Version 2.0 which attracted world wide attention and we received overwhelmingly positive feedback. For those who missed the press release, you can find it here. We recently released version 2.1 which includes 6 new antennas in the database and some great new features. Read more bout Version 2.1 in Newsletter 2.1.

Preview of Newsletter 2.1

Author: Robert Kellerman

In the previous two blog entries (part 1 and  part 2) I showed two different prototypes of the array synthesis tool and summarised what we learnt from various user tests.

Just before we started to plan the third prototype we all sat around the table once again. Something was wrong, but I couldn’t quite put my finger on it.

It turns out that it is devilishly difficult to design an array while taking array element pattern into account. More importantly, the more elements you have, the less important the individual pattern becomes. Work that had been done quite a while before I had even started working at Magus included a design algorithm that designs arrays by assuming isotropic element patterns.

Furthermore, this is what antenna engineers also feel most comfortable with and why there was that unwillingness to start off with an element pattern each time.

Our terminology also had to be re-thought. “Array Calculator” became “Array Synthesis Tool” for the first time.

The three components: the array layout and excitation, element pattern and synthesized array were split up into three separate tabs.

Array tool: Final prototype (click to enlarge)

Once again, a prototype was drawn up and put in front of five users (click on the image above to enlarge the final prototype). This time, we had a winner. The only biggish mental hurdle was apparent in users who had tried the previous prototypes and who now wondered, briefly, where their element pattern was coming from.

After tweaking a few last things, the array synthesis tool could be specified and implemented. Click here for a more detailed description and screen shots of the final array synthesis tool.

Author: Carien Fouché

I want to pick up the story on how we implemented the Array synthesis tool in Antenna Magus. The previous part1 of this blog series can be found here. In part1 I asked readers to look at the first prototype and to write down or comment on their first reactions.

This is what we learnt from the original usability tests:

• The design confused people!
• Fitting antenna parameters into the current Design Mode palette is a problem. Fitting array parameters into the palette would be impossible.
• People don’t expect to be able to export a model of an array to a simulator. Most of the time, they are simply too big for full-wave analysis.

In the second design phase, we decided to go modal. The Array tool was separated from Magus’s Design Mode. One of the reasons for this was the sheer amount of information associated with arrays that had to be visible to the user. Another reason that emerged, after much discussion, was this: “Magus would not be taking mutual coupling into account.” By keeping the array calculator separate, we would not create that expectation. Parameters would be displayed in a large table in the main workspace, instead of trying to squeeze them in on the side-palette.

However, users would still start off by specifying an elemental pattern or dragging a pre-designed pattern of an antenna into the Array tool. After this, the excitation distribution and positions of elements, or some other objectives could be specified.

Array tool: Prototype 2 (click to enlarge)

The prototype was drawn up in Balsamiq and five more users were tested.

This time, the usability tests went much more smoothly, however:

• Users (as we expected) had trouble finding the array calculator
• They seemed unwilling to start off with an element pattern
• One tester began explaining the intricacies of measuring array S-parameter matrices to me and the difficulties of matching impedances. When I told him that this would not be taken into account by Magus, he said: “But this is useless! It’s just a starting point!” Which is when he realised the intended value of the array calculator.
• The design still felt a bit flaky, somehow.

Before designing the third prototype, we all sat around the table once again. Something was wrong, but I couldn’t quite put my finger on it.

In the 3d (last) part of this blog series, I will explain what final changes were made to the above prototype before we implemented the Array tool. Have a look at the above prototype so long (click to enlarge) and write down (or comment) what you think needed to change.

Author: Carien Fouché

Interview between Dan and Robert

“Of course the antenna design algorithms have to be validated! That’s what you’d expect from any good software.”

“Isn’t antenna design routine validation and model validation the same thing?”

 
After hearing these comments I decided to move the spotlight onto Dan “our validation man” to see what validation is all about. He is the person charged with the job of ensuring that the algorithms used for antenna designs and antenna models that are exported from Antenna Magus are validated and can be trusted.

My chat with Dan went something like this:

Me: Hallo Dan, I heard a lot of positive feedback from our users that they love the fact that the exported simulation models are “ready to run.” Can you please explain how you do it?

Dan: It is always great when we get positive feedback, but I definitely can’t take all the credit. It is a team effort between the engineers and myself.

Me: Some people think model validation and design routine validation is the same thing. Can you explain the differences?

(more…)

If you do not like to drink coffee the reason is you haven’t tasted good coffee… well that’s what happened to me at least. I never liked coffee and now I love it! The secret can be summed up in two words: “freshly roasted”.

A couple of us at Antenna Magus take coffee quite seriously and this number is growing. This week one of our antenna engineers brought his “coffee roaster” to the office and we photographed the roasting process as seen in the picture below.

The coffee roasting process

This was actually done using a hot-air popcorn popper – like the one here (which costs +- R 150/ $20 US). If you like coffee and want to give this a try, you have to do the following:

1. Buy green coffee beans. Don’t just settle for anything -the best coffee comes from Africa (specifically Ethiopia and Kenya). Hawaii also has good coffee but it is overpriced and some Mexican coffee is also very good. These are all Arabica coffees which we prefer, but you may disagree as taste is a matter of personal opinion.
2. Take a handful of green beans and pour them into the roaster. You get different types of roasters (or poppers as non coffee roasters like to call them) so the best way to determine the amount of beans you can roast at a time is to switch on the popper and slowly add more beans till just before they stop moving or rotating. If there are too many beans in the popper, the beans at the bottom will be burnt before those on top have even started roasting – and your coffee will be terrible!
3. Watch the beans as they start changing colour from green to light brown. As the beans begin to roast, they expand and become lighter and will start spinning more vigorously until they start hopping and jumping and small pieces of husk (we like to call it chaff) will start blowing off. Some people use a coke can with open ends to extend the hole of the roaster – this stops the beans from escaping when they expand and over-fill the popper bowl.
4. By now you should hear a cracking sound – the beans have reached “first crack” stage and have expanded to 130% of their original size. This should happen after 3 – 6 minutes depending on the roaster’s wattage, ambient temperature and type of bean.
5.  The next stage is “second crack” which usually happens about 2 – 3 minutes after “first crack”. The cracking noises at this stage are slightly less pronounced than the “first crack”, and this is where you have to be very careful not to burn the beans. Depending on how dark you prefer the roast you can stop roasting just before “second crack” for a lighter roast up to about 30 seconds after “second crack” has started for a very dark roast. I usually stop 10 seconds after the start on “second crack”.
6. The final step is to cool down the roasted beans as quick as you can. The interesting thing here is that from somewhere around the “second crack” stage, the roasting becomes exothermic, and will keep going even after the heat is removed. If you don’t cool down the beans quick they might start to smoke and get burnt. The best way to do this is to put the beans into a big metal container that will disperse the heat, and fan them for a short while to cool them down – I use a big old cooking pot, but any metal bowl or pan should also work. 

I recommend roasting outside, where the chaff will not cause a mess and remember to make sure that there are not too many people close by as they WILL harass you for some of your coffee once they’ve smelled the aroma of the fresh roast filling the air.

Flavor peak is 12 – 48 hours after roasting but it still tastes very good immediately after roast. We use a second hand Nouva Simonelli industrial espresso machine at work (purchased from an out-of business restaurant that regularly has to be repaired – but that’s a different story on its own!)

So what has this got to do with antenna design? Nothing! I guess fresh roasted coffee is great, just like Antenna Magus!

Author: Robert Kellerman

The Antenna Magus product launch went extremely successful, well nearly too successful we thought…

Antenna Magus was launched on the 1 May 2009. The date had been fixed months before and we had to GRIND to meet this deadline. Little did we realise that the 1st was a Friday and probably not the best day of the week to launch a new software tool!  And due to some unforeseen errors the website only went live on Saturday around lunch time.

Emails were sent out on Friday morning 1st of May at approx 9am to  +- to 20 000 recipients inviting the whole EM microwave world to go check out:

“the first antenna design software tool of its kind.”

It was a slow start (which probably gave the web server a chance to find its bearings) but surely the web traffic steadily increased and so did the free evaluation downloads. Early Monday morning it appeared as if someone was downloading the internet from our server! 100s of MB’s every minute! We thought this must be a bot that is crawling our site, trying to suck the life from our web server in Germany. So we checked with CST and FEKO,  (who link directly to our server to download the Antenna Magus installs) and they suggested that the traffic was genuine – people who just got an email announcement and had downloaded the evaluation version.

By Monday 5pm there were already 500 downloads of the evaluation version and nearly 300 views of the marketing video (which I’ll blog about a bit later) . By now the number of daily evaluation downloads has stabalised and the sales are starting to roll in…and we haven’t stopped smiling since.

Author: Robert Kellerman