For more than a decade, RF
Cascade Workbook 2005™ has been the de facto standard for spreadsheet-based
RF system cascade analysis. Wireless System Designer™ is the next phase in the
evolution - not just an upgrade from RFCW2005. If you know how to use Excel
and you know anything about cascaded system calculations, then you know how to use
RF Cascade Workbook 2018™(aka Wireless System Designer™).
This is significantly easier and faster than using the multi-thousand dollar simulators
when a quick system analysis is all that is needed. Hundreds of hours have gone into
developing this tool. Please see Wireless System Designer™
intro video below for an overview of features.
Mouse-over Comments for Cells
Excel's cell comment feature is use extensively
to provide guidance for Wireless System Designer™ (WSD). The contents of all
the hints - and more - can be found on the "Help" worksheet (click
the tab at the bottom). The "Help" worksheet, cell mouse-over comments, and this
web page comprise the totality of documentation for Wireless System Designer™.
There is no separate document available. RF Cascade
Workbook 2005™ should also be useful since it extensively documents formulas.
Combined, there is a lot of information about not just how to use WSD, but also how cascaded
system analysis works. RF Cafe is also chock full of
related information, so one way or the
other, you're covered.
Assistance: Because the price for Wireless System Designer™
is so low, I cannot provide any level of assistance with setup
or operation. After all, you're getting an amazingly feature-filled program for less
than an hour of an engineer's billable time. Reported errors, if any, will be addressed
Macros: You must enable macros
to run or you cannot use Wireless System Designer.
System Requirements: Excel 2007 & Windows 2008 or newer.
These instructions and screenshots were made in Excel 2007, so your screen and menu placements
might be a little different. I verified that everything works fine all the way through
Help: Here is the complete
Help Page from Wireless
by United States copyright law. Unauthorized copying, alteration, or distribution of
this spreadsheet is prohibited by law. As a lawful owner of a Wireless System Designer™
user license, you are permitted to make modifications for your unique application; however,
this workbook may not be modified and distributed or sold as a new product.
Designer™ is offered AS IS. Your use of Wireless System Designer™ implies
you alone accept responsibility for results obtained through its use, and will hold harmless
Kirt Blattenberger, RF Cafe, and all legal assigns for any losses incurred through its
use. Wireless System Designer™ has been tested very thoroughly, and there are
no known problems at the time of this release. Discrepancies that affect accurate results,
if discovered, will be fixed ASAP and a replacement version will be provided at no cost.
Also, any and all User modifications to Wireless System Designer™ - other than
entering values in the provided Unlocked cells, negates any and all responsibility by
RF Cafe for the integrity of the software. Unprotecting a worksheet negates responsibility
by RF Cafe.
Locked vs. Unlocked Cells and VBA Code
The built-in ability of locking cells
to prevent unintentional overwriting of formulas is used in Wireless System Designer™.
Most of the time the protection can be left on. Trust me, even after becoming familiar
with use, you will still find yourself accidently attempting to type into formula cells,
and of course doing so invalidates calculated results. Probably the only time you will
need to remove protection is when inserting or deleting columns or rows. I recommend
never Unprotecting any worksheet since doing so invalidates the integrity as provided.
Be sure to reapply Protection if you decide to Unprotect. See the WSD
Protecting & Unprotecting the Worksheet
Use Excel's Protect Sheet and Unprotect Sheet commands to lock and unlock, respectively,
the cells. Use the Password provided in the e-mail sent to you with the file attached.
I will be glad to provide it to you again with a proof of purchase.
When Protecting the worksheet, be sure to select ALL the check boxes in order to ensure
that the macros will run (click thumbnail above). You might
need to scroll down in the window to access all the check boxes. See
information on the WSD "Help" page.
Since the complete worksheet occupies
nearly 900 rows, a convenient drop-down menu is provided to move up and down the page.
Information necessary for the navigation to function is in the cell behind the menu,
so if you accidently overwrite the cells, navigation no longer works
(keep Protection turned on).
Hiding and Unhiding Columns
Rather than deleting and/or adding component stage
columns, it is much simpler to Hide and/or Unhide columns. Doing so retains all the information
without having to go through all the steps needed for deleting and/or adding columns.
All the input and calculated is retained and included in the overall output, but the
Hidden stage columns are not included in the charts. Hiding component stage columns can
be a good way to exclude unneeded plots from the charts without requiring you to delete/add
data series - which is itself a pain to do.
System Cascade Charts
Charts are pre-configured for plotting all calculated
cascade parameters. Auto-scaling of the axes is the default, but you can change all aspects
of the chart formats per Excel standard. Select chart to display using drop-down menu.
These four top-level overall system parameters
are used for many calculations. Be sure to define them along with the individual stage
Build System Block Diagram
Build your system block diagram using the provided
images or make your own. Click on the "Icons" tab at the bottom of the page to access
and copy the desired icon (58x32 pixels), then paste it into the block diagram. Use Excel's
standard Objects alignment and spacing tools for a perfect layout.
Specify Component Parameters
Enter each stage's nominal and tolerance values.
Error checking is provided for exceeding power or gain limits (see below), no negative
noise figure (NF), making sure NF is equal to absolute value of a negative gain component,
etc. Errors are reported in the "Status" cells. Two rows f user-defined cells are provided
for formulas along with a "User Defined" chart that displays the cell data.
Set Limits on Gain and Power Input Values
Set maximum values for stage component input parameters.
These values are used for Data Validation in the input parameter cells. This results
in a limit where the charts auto-scale, since entering a null value of, say +999 dBm
for IP3 will render its affect utterly unnoticeable by the system, the IP3 chart will
auto-scale to +1000 dBm or more while the IP3 level in your actual system might
be a maximum of +50 dBm. The useful data would then be crunched almost entirely
at the bottom 5% of the chart. Of course you can always go in and manually scale the
chart axis minimum and maximum values as desired if you do use +999 dBm as the null
value. This just keeps things reasonable in case you prefer to let the charts auto-scale.
Besides, +100 dBm is good enough in most instances.
Specify Lower and Upper Frequency Sweep Limits for Filter Calculations
Enter the lower and upper frequency range for calculating
the system response inclusive of filters and frequency conversion stages. 175 equally
spaced frequency steps are calculated for all stages. Depending on your system, you might
want to do sweeps across the entire input band of concern, then do narrower sweeps that
will provide finer detail within your smaller filter bandwidths.
Note: the Lower frequency cannot be zero (0) because
of the logarithmic horizontal chart scale. The smallest value permitted
is 10-12, which is small enough to include 1 Hz even when the Upper frequency
is 1 THz.
Every stage can contain a frequency-dependent
component which can be an actual filter or a model of the frequency response of an amplifier,
cable, coupler, etc. WSD checks to make sure all required inputs are present and alerts
you if they are not. For example, if you select a bandpass filter and do not enter a
lower frequency or if you use a Chebyshev and do not enter a ripple value (or if you
enter invalid values, like lower frequency greater than upper frequency).
Frequency Translation (Mixers | Modulators) Specifications
As with the filter specifications, every stage
can have a frequency translation. That means there is no limit to the number of frequency
conversions your system can have, although from a practical standpoint you will probably
never have more than three. WSD checks to make sure all required inputs are present and
alerts you if they are not.
Frequency-Dependent Power Levels
Frequency-dependent power levels based on filter
responses and frequency translations are calculated separately from the other system
cascade calculations (NF, IP2, IP3, etc.). Along with the filter response, all nominal
stage component gains are included. Results are plotted in the "Frequency Response" ("Signal
Power vs. Frequency") chart. These frequency-dependent gains and power levels are
not used in any of other cascade calculations (NF, IP2, IP3, etc.). Note that frequency
and power levels presented this matrix are actually calculated in cells below Row 540,
but are done this way to conveniently place power levels next to their associated frequencies
while making data selection for the chart simpler (take my word for it).
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 Internet was still largely an unknown entity at the time and not much was available
in the form of WYSIWYG
All trademarks, copyrights, patents, and other rights of ownership to images and text
used on the RF Cafe website are hereby acknowledged.