Steven S. Holland

I need to take some time to find a good plugin and get this site setup so that spam comments are reduced — I am getting upwards of 10 spam comments a day at this point — but until then I am shutting them all off.  Currently I don’t even look through the comments in the moderation queue so I don’t want someone to post a comment and then it get buried in the spam noise.  So, if you have commented in the last few months, and it never showed up…this is likely why.

Every now and then I write or modify a matlab function that I need for my research, and will post them to this blog here and there, with the hopes that they will be useful to someone doing antenna/microwave design.  I know, there is the Matlab File Exchange (which is very useful!) , but hey, this is my blog, I want to post my content here.

Below is a function I used to plot smith chart results in matlab.  I used basic plotting code to generate the chart itself, and added a simply plot function to add the impedance locus and constant VSWR circles.  Hope this is helpeful!  Please let me know if anyone finds a bug.  I will note that there is no safeguard in the function for s-parameters that are greater than 1, which if you are plotting the active S-parameters of a multiport device, are possible.  This isn’t a big deal when the S-parameter goes slightly above 1, but if it swings well above 1 you end up with a tiny smith chart and these erratic line segments…it’s a mess.  For passive applications I haven’t come across a bug yet.

smithchart.m

After spending most of the season in first place, it was looking dicey as it wore down and they slipped into 2nd place last week… but they pulled it off tonight!  Although I would have rather went to the game (as most of my family and friends got some of the tickets for tonights game….man!) than watch in the local bar ( I don’t have cable…) with a bunch of people rooting for minnesota to win, it was a great game.  I listened to half of the game online (it’s the only cheap way to get most their games, having lived outside of chicago for 6+ years now…), and then decided that this wasn’t doing it service, and of course it was on national TV tonight.  Thursday is going to be an interesting day — 1st playoff game vs. Tampa Bay, and the VP debate!

My friend Bill Whirity (see link to his website on the side) is making a movie (look for his other movie Broke on netflix!…I was supposed to be Eddie Beats but had my wisdom teeth out right before shooting…I digress) called The Misadventures of Milo Weatherby.  From what I have seen of it, it will be awesome.  It is about these two kids and their, well, misadventures with science. They just finished shooting it, so no idea when it will be out.  Here is a great video from it:

http://billwhirity.com/milo/videos/microwave_implosion.mov

The last couple days have been full of some nasty, although short-lived storms.  It has been very hot and humid, and so these mid-afternoon/early-evening storms build up.  On friday I was walking home from campus and got caught in the middle of a really, really bad storm.  Tons of lightning nearby, which isn’t good when walking past huge open farm fields, and torrential rainfall, making it hard to see maybe a quarter of a mile down the road.  I was left with thes two options: take the meager shelter offered by the bus stop I came to, and maybe hop on a bus that may be here any minute, or could be up to an hour away from making this stop, or start running.  Noting the amount of lightning and the tiny bus enclosure next to some huge trees, I decided it was unwise to stay at the bus stop.  So I started sprinting the 3/4 mile back to my apartment in the pouring rain, with sandels on, and my macbook in my non-water resistant messenger bag.  I made it back to my apartment, soaking wet, but thankfully my macbook and the contents of my bag were relatively dry.  Also, as soon as I got in the front door of the house my apartment is in, the storm picked up tremendously - both in rain and amount of lightning.  Then the power went out, I actually heard the transformer down the street pop from a lightning hit.  The top half of a huge evergreen tree in my backyard fell over, not sure if it was from the wind or lightning.  Lots of big branches down up and down the block.  Power was out for about 5 hours, and campus lost power over that time too.  This is where my problems actually started.

When the power came on at my apartment, I tried logging into my work comp, which couldn’t because the network was down, and I later found out was off due to the power going out.  So on saturday I ride my bike over to campus to do a little work, which I could have done from home if my computer wasn’t off.  I took the long route to campus beause that route is makes for an interesting ride, and I was in no hurry to get to campus, but when I was halfway there near a farm (which allowed me to see, instead of the tree lined roads), off to the west I can see really dark clouds forming.  “Oh crap”, I thought, I am gonna get caught in another storm.  So I picked up the pace and made it over to campus in time for it to start pouring — even harder than on friday.  And wind like I have never seen here — huge gusts blowing the rain straight sidways.  And while storming pretty bad, the lights dimmed a few times, the emergency lights flickered on for a split second — I then decided it wan’t worth running my computer given the possibility of losing power again or, worse, a surge.  So I unplugged my computers, including the ethernet, and got a ride home from a friend in lab.

So today (sunday), I head over on the bus and intend to restart my computers, and ride my bike back to my apartment.  No storm was on the verge of exploding when I got to lab, so I figured my luck was changing.  Instead, in complete sunshine, the power goes out in our building.  The building next to us had power, but we did not.

So for three days in a row my computer has been down for the count, and I won’t have the simulations I was hoping to have tomorrow, monday.  My luck stinks right now, it turns out!

Sox won 5-4 tonight over the Rockies.  Good rally in the 7th won the game for them.

I always like this view from the ramps at New Comiskey (Us Cellular Field):

Turns out that Creative was sued for basing the listed size of its hard drives in base 10 instead of base 2, leading to lower actual capacity than the drive’s advertised size. Link!

I bought 2 creative hard disc MP3 players between 2005 and 2006, so apparently I am entitled to either 50% off a 1GB player or a 20% discount from their website. This may mean some purchases are in order from Creative!

I have been getting a lot of comments and trackbacks that are spam, so I reluctantly are changing it so that i have to approve all first comments for them to appear.  After that, if you have had a comment approved, you should be able to post as normal.

Finally today I went in and finished off my antenna measurements.  I had a problem last week that I wasted a lot of time trying to figure out — the main beam pattern was shifted approximately 25 degrees off broadside, which is clearly not right for a patch antenna.  Problem is, the range absorber isn’t meant to go down below about 2-3GHz…so it was possible some reflections were present and this was a range problem.  After a lot of attempts to ensure both antennas were level, and plum, and aligned…I finally came in today and took a friend from lab’s suggestion that I restart the computer that runs the antenna positioner.  I restarted it, and all was well.  It’s a silly problem, and I really wish I didn’t spend all day Friday trying to find the problem, but at least now I have the patterns I need.  Here is a picture of the transmit antenna - a simple rectangular patch antenna -  I had to build, since the range doesn’t have horns that go down to 1GHz:

This is, I think, our third or fourth snow day of the 2007-2008 school year.  It seems like it has been a long time since the weather has been this snowy.  Back in 1995-1996 or so, I recall having days off of grammar school due to it simply being too cold (-5F, etc), and then maybe a few times throughout high school.  So it has been a while.  Then again, not having any classes this semester means nothing really changes for me — I still spend today writing more of my thesis….just as I would be anyway.