RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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and text used on the RF Cafe website are hereby acknowledged.
Randy Rogers*, AD7ZU, mentioned in
the May 2020 issue of QST magazine the Smith Chart software called "SimSmith," by Ward Harriman, AE6TY.
SimSmith first appeared around 2011. Being written in
Java, it will run on any operating system that
supports Java (Win64, Win32, Apple Mac OS X, Solaris, and Linux). If you are using
Win64 as I am, you will want to download the "windows64-with-JRE.exe" file. Windows
security will try to block it, but it is safe to run after your antivirus program
scans it and gives a green light. AE6TY recommends using the installation files
rather than just downloading the "SimSmith.jar" file even if you already have a
version of Java installed.
When launching the program, the window might
not be very large, so grab a corner and stretch it out so the components are easier
to see. After playing around with SimSmith for a while, you might want to click
on the "SimSmith->preferences" menu selection to see whether there are default
settings that you want to change. The "line Width Multiplier" setting thickens the
with of all lines on the display - not just on the Smith Chart. Interestingly, "power
Units" can only be set to "dBW" or "W," with no option for dBm or mW.
It appears there is no limit on the number
of components that can be cascaded. The drag-and-drop user interface is very friendly.
Click on a component from the palette at the bottom of the screen and drag/drop
it where needed in the circuits at the top. Click and drag any component to a new
position as desired. Right-click on a component to expose the drop-down menu to
delete, rotate, copy, delete, etc. Component parameters can be easily edited in
place below the circuit cascade either by typing in a value or using the mouse scroll
wheel to increment the value. Changes appear instantly on the Smith Chart display.
Clicking on a line on the Smith Chart causes its corresponding component to be highlighted
in the circuit so you know what to edit to affect the line. Fortunately, using the
standard "Crtl+Z" will undo the last command, even after deleting a component.
I'm not sure whether this is significant
or not, but while experimenting with SimSmith I stumbled upon a swept waveform that
looks a lot like the recently discovered "heart" (Tombaugh Regio) of the planet
Pluto (I still consider it a planet). Could this circuit and its associated range
of frequencies hold some clue as to the electromagnetic nature of Pluto? Remember
that you saw it here first ;-)
Thanks to Mr. Rogers for this amazing program!
Larry Benko, W0QE, has produced
many SimSmith videos from various versions of the program.
"Ten thousand foot flyover of SimSmith's extensive capabilities."
"SimSmith Is An Evolving Program.
This means that over time, basic operation can change. Changes are made for a
variety of reasons: adding functionality, fixing bugs, making things 'consistent'
across subsystems, making things 'intuitive' for the user, meeting industry standards
and/or expectations, etc.
These changes can cause considerable angst, particularly when attempting to follow
along while watching a video. If you run into this problem I apologize. Please access
the help menu, referring to the 'SimSmith' manual, the 'recent changes,' or the
'release notes.' I try to at least say that something has changed and occasionally
- Ward Harriman, AE6TY
Posted April 15, 2020
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