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.
Feature Descriptions
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.
Important Notes
•
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 ASAP.
•
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 Excel 2016.
•
Help: Here is the complete
Help Page
from Wireless System Designer™.
•
Terms of Use Wireless System Designer™ is protected
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.
Disclaimer:Wireless System 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 Terms of Use information about liability.
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
Worksheet
Protection information on the WSD "Help" page.
Inserting and Deleting Columns
Please see this separate page with screen shots and directions showing how to
insert
and delete columns.
Navigating the Worksheet
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.
System-Level Parameters
These four top-level overall system
parameters are used for many calculations. Be sure to define them along with the
individual stage component parameters.
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.
Filter Specifications
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 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.
