Array Solutions AIM4170 User manual

ARRAY SOLUTIONS
350 Gloria Rd
Sunnyvale, TX 7518
www.arraysolutions.com
Antenna Analyzer AIM4170
Feb 7, 2007

Antenna Analyzer AIM4170 page 2
Table of Contents
Quick Start…………………………….……………... 3
Calibration……………………………….…………... 7
Commands…………………………………………… 11
Data Window…………………………….….…………19
Data Referred to Antenna…………..……….…………21
Analyzer Principles of Operation……….….………….28
Measurement of Crystal Parameters……….…………..32
Frequency Source………………………………………36
Appendix 1 – Specifications…….……….…… ……….37
Appendix 2 – Complex Numbers…………..… ……….38
Appendix 3 – Hot keys…………………………………42
Appendix 4 – RS232/USB Operation…………………..43
Appendix 5 – Scan Data File Format…………………...44
Appendix 6 – Battery Operation…..……………………47
Appendix 7 – Saving Screen Shots……………………..49
Appendix 8 – Configuration File……………………….50
Appendix 9 – Component Test Fixture…………………53
Terms and Conditions….…………….….……………...55

Antenna Analyzer AIM4170 page 3
Quick Start
Loading the Software:
The AIM4170 software does not require a formal installation procedure. It does not
interfere with any other programs or the registry on your computer.
1) Create a folder or a subfolder on any convenient hard drive.
For example, “C:\AntennaAnalyzer”.
2) Insert the CD labeled “AIM 4170” in the CD drive.
3) Copy all the files on the CD to the folder you just created for the antenna analyzer
software and documentation.
4) The file labeled “AIM_xxx.exe” is the executable file. It is ready to run without going
through an installation process. When later versions of the program are released, the
number “_xxx” will be different. All versions of the antenna analyzer program can reside
in the same folder at the same time. The older programs with the lower numbers will not
interfere with the newest version, so they do not have to be deleted.
If you want to make a shortcut icon for your desktop, right click on the AIM_xxx.exe file
(or the latest version) and select “create shortcut” from the dropdown menu. Drag the
shortcut to your desktop or task bar.
When the files are loaded from a CD, they may be flagged as “read-only”. In order for
the calibration and initialization data files to be updated properly, the “read-only” flag
must be cleared. Highlight all the files in the folder by pressing control-A and then
right-click to see the properties of the files. If the “read-only” property box has a
checkmark, uncheck it and then click “Apply”. This will remove the read-only flag on all
the highlighted files. None of the files in the folder need to be read-only.
Hardware Connections:
Connect one end of the RS232 cable to the antenna analyzer and the other end to COM1
on your PC. If you want to use a different COMM port, start the AIM4170 program and
click on the Setup menu at the top of the screen. Then click on Comm Port and enter the
port number (1 to 8) that you want to use. This number will be saved in the setup file
called AIM_xxx.ini. If you’re using a USB to RS232 adaptor, change your USB program
to match this number. For more information about setting up a USB/RS232 adapter, see
Appendix 4.

Antenna Analyzer AIM4170 page 4
Plug the DC power supply that’s included with the AIM4170 into an appropriate 120V
AC outlet and insert the connector into the jack on the rear panel of the analyzer.
Press the power switch. The Green LED will blink a few times to indicate the version of
software and then remain on continuously. The Red LED is on only when a measurement
is in progress.
To turn off the power, press the power switch again. If the analyzer does not receive a
command from the PC for 10 minutes, it will power down automatically if it is in the
AutoPwrOff mode. The default is to not power down automatically but if you’re using
batteries, the AutoPwrOff mode can be turned on with a menu selection under Setup.
The AIM4170 can be operated on battery power for remote operation with a laptop
computer. The current required is about 250ma while a measurement is in progress and
about 50ma when idle.
Batteries are not included with the AIM4170 but you can make a battery pack using any
type of batteries you like. There is room inside the case for a 9V battery and disconnect
diodes are included so the battery and the AC power supply will not interfere with each
other. There is also a space for an optional resistor to use for trickle charging a battery, if
desired. The main power on/off switch controls the battery power too, so the leakage
current is less than one microamp when the AIM4170 is turned off. Refer to Appendix 6
for more details. (These pictures show an AIM4160, but the AIM4170 is electrically the
same.)
Be sure the maximum input voltage at the DC power connector does not
exceed 15 volts. The minimum input voltage required is 6.0 volts.
NOTE: Low cost power supplies that plug in the wall are usually not regulated and their
maximum output when no load is connected may be several volts higher than their rated
output. Check the output voltage with no load to make sure it does not exceed 15
volts.
Some of the pictures in this manual were taken using an AIM430 or an AIM4160. The
operation of these instruments is equivalent to the AIM4170 (within their operating
ranges) and this manual applies to all three instruments.

Antenna Analyzer AIM4170 page 5
Initial Operation:
Launch the AIM_xxx.exe program. You will see a graph similar to this:
When the AIM4170 is present, it must be turned on before the PC program is launched.
If the PC program starts when the AIM4170 is not connected and powered up, the
program will automatically enter the DEMO mode.
For a quick test, connect the calibration resistor to the RF connector and click the SCAN
button in the lower left corner of the screen.
The Red LED will come on while the scan is in progress. A blue bar will move across the
top of the graph as the scan progresses.
You will see a set of traces (similar to the picture below). The actual values are not
important, but this shows the AIM4170 is functioning.

Antenna Analyzer AIM4170 page 6
Scan using a 301 ohm resistor for a test load.

Antenna Analyzer AIM4170 page 7
Calibration
The AIM4170 has no internal adjustments. There are no trim pots or caps inside. All
the calibration is done with the following software procedure.
Click on the Setup menu and select Calibrate Analyzer.
A message box will appear near the center of the screen, as shown below:
Attach the BNC connector with an internal short circuit (this is included with the
AIM4170, it is labeled “short”).
If this shorting connector is not handy, then a piece of wire, like a resistor lead, can be
used with good results too.
After the short circuit is in place, click Continue.
The program will run for a few seconds to take several reading of the short circuit.
Sometimes when calibrating with a coax stub or an external filter connected to the AIM
RF port, the impedance may appear to be significantly difference from a short circuit at
1MHz and a message will appear asking if this is a valid condition. If the connections are
correct and you really do want to continue with the special external hardware hooked up,
click YES. Otherwise, click NO to abort the cal procedure. Then after connecting the
desired load, restart the calibration.

Antenna Analyzer AIM4170 page 8
Then it will display a message box, shown below:
Replace the short circuit with an open connector (included with the AIM4170) and then
click Continue.
The program will run for a few seconds to take several readings of the open circuit.
For the best accuracy, especially at VHF frequencies, use an open connector of the
same type that is used for the short circuit. This allows the program to compensate for
the stray capacitance of the connector itself. For example, 3 pF of stray capacitance due
to a BNC connector represents a reactance of about 1K ohm at 50MHz which will appear
to be in parallel with the load. This will seriously affect readings at higher frequencies if
it is not properly compensated. Therefore, the three calibration devices (open, short,
resistor) should be carefully constructed so they have similar stray capacitance and
inductance which will be cancelled out by the calibration procedure.
NOTE: If you are using the UHF/BNC adapter (or another adapter) leave it on the
output connector of the AIM4170 when calibrating the open circuit. In this way, the
capacitance of the adapter itself will be included in the calibration process.
For example, If you want to use a BNC-to-binding post adapter, calibrate the short circuit
with a jumper wire across the binding posts. Then remove the wire and calibrate the
open circuit condition with the adapter still attached. This procedure cancels the stray
capacitance of the adapter and you can get accurate readings of discrete components
attached to the binding posts.
The calibration procedure can also cancel the effect of a piece of coax that is used as a
jumper to connect the AIM4170 to the load. In this case, the open, short and standard
resistor are connected to the far end of the jumper. Good results have been obtained with
as much as two feet (60 cm) of jumper coax.

Antenna Analyzer AIM4170 page 9
After taking several reading of the open connector, the program will prompt for the
standard resistor with a value between 50 ohms and 500 ohms. This resistor should be
mounted on a connector like those used during the open and short calibration steps. The
exact value is not critical. Enter the value you measured with a digital ohmmeter and
click Continue. If you are using the cal resistor that is included with your AIM, the
number printed on it should be entered. If you have a different cal standard, use that
value.
After reading the standard resistor, the Red LED goes off and the prompt for a
calibration data file name appears:
Enter the name of the calibration file and click “Save”. There is no restriction on the
name of the cal data file. It’s extension is automatically set to .acal (“analyzer cal”). Any
of these cal files can be recalled latter using the menu option “File” Load Cal File.
Then the cal complete message box is displayed as shown below:

Antenna Analyzer AIM4170 page 10
Click OK to continue.
Each time the AIM4170 program starts, the last calibration file that was used will be read
to restore the cal data.
Since there are no adjustments that have to be made inside the case, the calibration is
very stable.
This completes the calibration procedure. Now you are ready to begin testing your
antenna.
NOTE: Before connecting a transmission line to the input of the AIM4170,
be sure to momentarily short its pins together to drain off any static charge
that may be present. Also, be sure there is no DC voltage on the antenna. If
there is DC, use a blocking capacitor between the AIM4170 and the antenna
input.
Antennas and transmission lines can have enough static charge to damage sensitive
electronic equipment. This can happen even when there is no rainstorm in the area.
A strong wind can generate static charge. So can just flexing a coaxial cable by
rolling it up or unrolling it, even if there is no antenna connected to it.
An antenna or a component to be measured should not be connected or
disconnected from the analyzer while a test is in progress. A test is in progress when
the RED LED is on.

Antenna Analyzer AIM4170 page 11
Commands
The color of each trace corresponds to the color of the label at the top of the Y-axis.
SWR is RED and this scale is on the left side of the graph. On the right side the
magnitude of the impedance is the inside scale and the trace is GREEN. The reactance
is in YELLOW, also on the inside scale. Reactance and impedance use the same scale.
Reactance can be positive (inductive) or negative (capacitive). The phase angle of the
load impedance is plotted in MAGENTA and this scale is on the outside of the right hand
vertical axis. These colors can be changed in the configuration (*.cfg) file if desired.
The most common commands use the buttons along the bottom edge of the screen:
SCAN (S)– Starts the frequency scan between the specified limits: Start_freq to the
End_freq. (see Limits button below.) Each time the scan button is clicked, the graph is
cleared and the new scan data replaces the previous data in memory.
RESCAN (R) – A new scan is started but the graph is not cleared. This makes it easy to
see the before and after effects of changes to an antenna (or any discrete component
being measured). The new data replaces the previous data in memory but both graphs
can be viewed simultaneously. RESCAN can also be used to overlay new data on top of
a scan that was loaded from a data file. See “File -> Load” below.
RECYCLE – Scanning is repeated over and over until the RECYCLE or the HALT
button is clicked. This makes it possible to continuously view the results while adjusting
an antenna or tuning a stub. The resonant frequency is displayed above the graph and it’s
updated after each scan during recycle. The scan limits can be adjusted to narrow the
scan range for a faster update rate.
POINT DATA (D) - Measure the impedance at a specified frequency. This is used for
diagnostics. The measurement can be a single-shot reading or repeated about 2 times per
second until the point data window is closed.
In the recycle mode, a set of buttons appear in the data window to allow the test
frequency to be incremented or decremented.
LIMITS (L)– When this button is clicked, a dialog box, as shown below, pops up for
entering the start and stop frequencies and the size of the frequency increment (step)
between measurement points. The start and stop frequencies range from 0.1MHz to
170MHz for the AIM4170.

Antenna Analyzer AIM4170 page 12
For example, to scan the 40-meter band, you might enter 6.9MHz for the Start
frequency, 7.4MHz for the Stop frequency and 0.01MHz for the frequency Step (the
spacing between measured points). This would result in a scan of 50 points across the
band. The maximum number of scan points is 300 and the minimum number is 5.
You can also enter a number in the Step (delta) box and follow it with the letter “p” for
“points” and the scan will use that many data points. If the number in the Step box is
followed by a percent sign “%”, the step size will be that percentage of the total scan
width.
Note that when using the cursor to read out numeric data (discussed in detail later), the
displayed values are interpolated between the measured values. Therefore, in some cases
it may be desirable to use a larger frequency Step for a faster scan rate. You can still
read the parametric values at intermediate frequencies with the cursor. The scan rate is
about 15 to 25 points per second, depending on the speed of the PC. The program can be
run on older, slower computers with Windows 95 but the scan rate may be slower.
SCALES - When this button is clicked, a dialog box pops up for entering the full-scale
values for: SWR, Zmag (impedance magnitude), Theta (deg), and Return Loss (db).

Antenna Analyzer AIM4170 page 13
If the actual measured value is off the scale (flat line at the top of the graph), the value
readout by the cursor is still valid since it uses the raw data stored in memory. For
example, you can set the Zmag scale to 500 ohms in order to see fine details but if the
impedance actually goes up to 1600 ohms at some frequencies, the cursor can still read
the true value and display it in the data window.
If you select a new scale factor, the last data scan will be replotted using that scale.
SMITH – A window is displayed with a
Smith chart showing a plot of the
reflection coefficient versus frequency.
As the cursor is moved with the mouse
over the original plot, a marker dot is
displayed at the corresponding point on
the Smith chart and the relevant data is
displayed in this window.
Note, the point that is highlighted on the
Smith chart corresponds to the
frequency on the horizontal frequency
axis of the original graph. This graph is
under the Smith chart and the horizontal
axis may not be completely visible, but
the actual frequency that the cursor is
pointing to is displayed on the Smith
chart itself.
This particular plot corresponds to the
scan shown on page 23 which uses 28
feet of RG58/U terminated with 301
ohms.
[The center of the Smith chart
corresponds to 52 ohms in this
example. The Zo value is specified
using the Setup Menu.]
COMMENT – A dialog box pops up for you to enter a comment that will be displayed at
the bottom of the graph. This is very useful for documenting the test conditions. This
comment will appear in a screen capture or a screen print and it will be saved in the raw
data file on disk if this scan is saved.

Antenna Analyzer AIM4170 page 14
HALT - While the scan is in progress, you can stop it by clicking this button. This is
different from the QUIT button (shown below).
QUIT – This stops the program, saves the setup conditions (limits, scales, etc) and exits
back to the Windows OS. When the program is launched again, the setup conditions and
calibration data will be restored automatically.

Antenna Analyzer AIM4170 page 15
Commands on the menu bar at the top of the screen:
FILE:
Load -- Load a raw data file from a previous scan. After this file is
loaded, its data is just like the original scan. The cursor can be
used to read out the numeric values.
When a data file is being displayed, the name of the file appears
at the top of the graph.
Save -- Save the raw data for the last scan that was done. If you clicked
the RESCAN button, the data that will be saved is for the last
scan. Even though the earlier scan is being displayed on the
graph, its raw data was replaced in memory by the new data
corresponding to last rescan command. The raw data is saved in a
file with the extension .scn. Another file is created with the same
name and the extension .scx. The .scx file has data in a format
that can be read into a spreadsheet. The format of this file is
shown in Appendix 5.
Print -- Print the graph on the system printer.
Load Calibration -- Load a calibration data file for a particular test setup or adapter.
These files have the .acal extension.
Load Config -- One of several configuration files can be loaded. A selection
window will show all the files in this folder with the .cfg
extension.
Quit -- Stop the program and exit.
This is the same as the QUIT button at the bottom of the screen.
FUNCTIONS:
Measure Cable -- This command is used to measure several parameters related to
the transmission line. A message box pops up to prompt that the
cable should be either open or shorted at the far end for these
tests to be valid. After this is ready, click OK to continue.
Other dialog boxes prompt for the velocity factor and the length
of the cable, if known. If the length is entered as Zero, the length
will be determined using the velocity factor that was entered. If
the length is non-zero, the length is assumed to be accurate and
the velocity factor will be determined.

Antenna Analyzer AIM4170 page 16
Distance to Fault -- Measure the distance to a cable open or short. This can also be
used to measure the ¼ wave length frequency of tuning stubs.
Refer to Antenna -- The impedance readings are transformed to be equivalent to
readings directly at the antenna terminals. Select either Method A
or Method B from the drop-down menu. Click OFF to exit from
the “refer to antenna” mode.
Constant Freq -- Output a constant frequency that can be used as a test signal.
Initial frequency accuracy is +/-30ppm. At 1MHz, the output
amplitude into 50 ohms is about 25 to 30mv-rms (-18 dBm) and
somewhat less at higher frequencies.
Measure Crystal -- Measure the parameters of a quartz crystal automatically.
Details are in a later section.
¼ Wave Stub -- Adjust a coax line to be 1/4 wavelength at a given frequency. The
target frequency and the initial length (in feet) of the coax are
entered in the dialog box. Then the graph runs in recycle mode
and displays the amount of the line that needs to be cut off
("Excess Length") to reach the target frequency. A vertical red
line on the graph highlights the target frequency. The magenta
colored phase plot crosses the horizontal axis at the quarter wave
frequency.
CALIBRATE:
Analyzer-- Calibrate the AIM4170 using open circuit, short circuit and
resistive load conditions. The calibration data is saved in a disk
file that’s read each time the program is started.
Cable -- Data for the cable is generated to be used by the “ref to antenna”
mode when reference Method A is selected.
SETUP:
Plot Parameters -- Select the parameters that are plotted during a scan. The optional
parameters are: SWR or reflection coefficient, Return Loss,
Impedance Magnitude, Series Load Circuit or Parallel Load
Circuit, Theta (phase angle).
Enter Zo --
Enter the nominal impedance of the transmission line. This is
used to calculate the SWR. This is a real number, there is no
imaginary part.

Antenna Analyzer AIM4170 page 17
Average Readings- Each data point is obtained by averaging two or more ADC
readings to reduce the effect of measurement noise. When
this option is selected, “AVG =N” appears in red in the
upper right corner of the graph. N is the number of readings
being averaged and is between 2 and 16.
Comm Port -- Enter the RS232 port used for communication.
Port values can be 1 to 8. This is saved in the initialization file
that’s read each time the program is started.
Morse -- Three values can be sounded out:
Sxx.xx= SWR, Zxx.xx=Zmag, Txx.xx=Theta.
The decimal point is coded as “R”. This is active when
the “Measure Point” function is used (see above). Morse output
is
enabled by clicking the “ON” button and disabled by the “OFF”
button.
AutoPwrOff This button enables/disables the automatic power down feature of
the analyzer. The enable/disable flag is saved in the analyzer
initialization data when you exit from the program (QUIT) and
restored each time the program is started again. The green LED
on the front panel of the analyzer blinks when this command is
executed. The default timeout delay is 10 minutes.
If you never use batteries, you may want to leave this feature
turned off.
BANDS:
Highlight -- Highlight the amateur radio frequency bands. These frequencies
are specified in the configuration file (*.cfg). The start/stop limits
do not have to be the actual amateur bands. The highlight color
can also be specified in the config file.
160..2 meters Click on the desired band to set the start/stop scan limits and the
frequency step between measurement points. These limits can be
changed in the configuration file.
Band A..D User specified band limits. Same as above.

Antenna Analyzer AIM4170 page 18
UTILITIES:
L-C Matching
Networks by WY2U This program which is available on the web takes the impedance
data (R and X) that is measured at the input end of the
transmission line and calculates the L-C network required to
transform it to the correct impedance (for example, 50 ohms) to
match the transmitter. This can be used when designing a tuner to
find the components to match an antenna over the desired
frequency range.
When you click on this link, your computer must be connected to
the internet. You may have to authorize the connection if you
have a firewall program.
ZPlots by AC6LA This program uses the data saved in the .csv file (by "File Save")
to plot graphs for presentations. It features plot parameter
selection and zoom capability. It can plot parameters that were
not included in the original AIM plot and the plot range can be a
subrange of the original data.
When you click on this link, your computer must be connected to
the internet. You may have to authorize the connection if you
have a firewall program. You can download the Zplots program
to your computer and then run it off-line.
HELP:
Help -- A help file pops up in the local browser. This is in html format
and can be edited by the user if desired. The file name is
“help_xx.htm”.
About -- The present version of the programs in the PC and the controller
are displayed. The url of the W5BIG website is also displayed.
Check this url for the latest software.

Antenna Analyzer AIM4170 page 19
Data Window
After a scan (or after loading a file from disk), the mouse can move a cursor along the
frequency axis and the numeric data for several parameters will be displayed
continuously in a data window on the right side of the screen. An example is shown
below:
The light cyan vertical line is the cursor. It moves with the mouse whenever the mouse
pointer is inside the graph area. In this example, the frequency is 46.000 MHz. The
frequency changes in 1-pixel increments due to the mouse resolution, so some specific
frequencies may not be displayable. The data is interpolated between the actual data
points that were recorded during the scan. The cursor can also be moved in small
increments using the Left/Right Arrow Keys on the keyboard.
Normally the cursor moves whenever the mouse pointer is inside the graph area. There
is an option in the configuration file to enable the cursor only when the left mouse button
is pressed.
Data in the window shows the characteristic impedance, Zo, has been specified to be 73
ohms. The SWR at 46.000 MHz is 3.099, Zmag=216.384 ohms, and Theta= -15.228
degrees. Note how the SWR decreases slowly as the frequency increases. This is due to
loss in the coax. Less energy arrives back from the reflection at the far end, so it appears
to the measurement system (or the transmitter) that the reflection is not as bad as it really
is.

Antenna Analyzer AIM4170 page 20
Parameter values for both a series and a parallel equivalent circuit are shown as Rs, Ls
(series circuit) and Rp, Lp (parallel circuit). Note that when the phase angle, Theta, is
negative, the equivalent components, Ls and Lp, change to Cs and Cp automatically.
At the top of the graph in the main window, up to five resonant frequencies of the
antenna are displayed. These are the frequencies where the phase angle passes through
zero. At these frequencies, the magnitude of the impedance is a maximum or a
minimum.
The names of the calibration and configurations files being used are shown in the lower
right corner of the data window. The color used to display these file names can be
selected in the configuration file.