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CST Array Wizard User‘s Guide
User inputs will automatically be set up as parameters. Thus, it is unnecessary to manually define parameters. Please use only numbers
as inputs.
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Setup and Plot Farfield Array
If the Setup and Plot Farfield Array option is selected, a new farfield pattern will be created using the Farfield Array feature. All other inputs
will be considered.
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If the Construct Finite Array from Single Element option is selected, the “unit cell” (including ports, lumped elements, and wires) will be expanded to an array based on the Array Geometry settings. If
Excitation Settings are specified, the appropriate values will be entered in the Excitation Selection dialog and the Simultaneous Excitation
feature will be enabled.
Construct Finite Array from Single Element
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Construct Finite Array from Single Element
Note, when creating large arrays, the macro execution can take some time. Please be patient.
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Construct Finite Array from Single Element
With a non-rectangular lattice (Grid Angle ≠ 90), some array elements will fall outside the “S1*Number of Columns” bound as shown above.
These elements will be referred to as “spill-over” elements.
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Construct Finite Array from Single Element
The “spill-over” elements can be removed or retained, by respectively checking and un-checking the Remove spill-over elements option. In
addition, the Shift first element by __ % specification allows the user to intentionally create “spill-over” elements in the first row(s) as shown in
the picture on the right.
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Simultaneous Excitation: Update Am/Ph Distribution
If the Simultaneous Excitation: Update Am/Ph Distribution option is selected, the values entered in the Excitation Selection dialog will be
updated accordingly based on the Excitation Settings specified.
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Note, if Simultaneous Excitation: Update Am/Ph Distribution is used, the Array Geometry settings must be the same as when Construct Finite
Array from Single Element was used. For convenience, these settings are automatically restored.
BinomialScan Theta =
0
Cosine^2Scan Theta =
30
Simultaneous Excitation: Update Am/Ph Distribution
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Perform Combine Results: Setup Am/Ph Distribution and Execute
If the Perform Combine Results: Setup Am/Ph Distribution and Execute option is selected, the Combine Results dialog will be updated
appropriately, based on the Excitation Settings specified, and the farfield combination performed.
As with Simultaneous Excitation: Update Am/Ph Distribution , the Array Geometry settings must match and thus are restored
automatically.
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If the user has pre-calculated amplitude weights and/or port phase values, they can be loaded using User Defined and Load file…
respectively. The imported file(s) should be formatted in the tab delimited manner shown above.
User Defined Excitation Settings
Port # <tab> Mode # <tab> Amplitude/Phase
Example:
Imported file format:
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User Defined Excitation Settings
When using these features, the port numbering convention must be known. Ports are assumed to be numbered consecutively from Xmin to Xmax, and Ymin to
Ymax. Thus, port 1 will be at (Xmin, Ymin) and will increment progressively until reaching (Xmax, Ymin). The next port number will be located at (Xmin, Ymin+1)
and the cycle repeats until reaching (Xmax, Ymax).
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Background InformationBinomial Amplitude weights: When this option is selected, the amplitude weights will be equal to the normalized binomial coefficients. The binomial coefficients can be calculated with:
!1!
!1
mNm
Nxam
1...,,1,0
Nm
N number of linear array elements
Cosine and Cosine^2 Amplitude weights: When one of these options is selected, the amplitude weights will be calculated (and normalized) based on a cosine/cosine^2 distribution over the aperture of the array using:
Cosine Cosine^2
xL
xam
cos)(
x
L Length of the linear arrayDistance from the array center
xL
xam2cos)(
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Background InformationChevbyshev Amplitude weights: When this option is selected, the amplitude weights will be calculated based on Dolph-Chevbyshev synthesis. The amplitude weights can be calculated with:
21
10 2coscos2
2 TN
sTTM
Tm NmsNszTr
Na
rMz
r
NM
N
T
T
10 cosh1cosh
1
Number of elements in a linear array
relative sidelobe level (linear scale)
where
12
10 12coscos2
2 TN
sTTM
Tm NsmNszTr
Na
21...,,2,1,0 TNm
For odd
TN
and
12...,,2,1,0 TNm
For even
TN
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Background InformationTaylor Amplitude weights: When this option is selected, the amplitude weights will be calculated based on the modified sin z/z distribution, often referred to as the Taylor one-parameter distribution. The sampled amplitude weights can be calculated with:
BI
Lx
BI
xa
0
2
0 21
B
x
L
I0 modified Bessel function of the first kindlength of the linear arraydistance from the center of the arrayparameter to set the relative sidelobe level
Since Bessel functions are not a standard VBA function, the equivalent summation is used:
0
2
2
0!
25.0
k
k
k
zzI
Since an infinite sum would take too long, the summation is truncated when the remaining terms are less than 1e-9.
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Background InformationScan Angles: The appropriate phasing at the ports to scan the main beam to the direction specified by Scan Theta and Scan Phi is automatically set up using:
0000 sinsinsincossin2
,
jiiji yxyxp
0
0
i
j
i
y
x
wavelength
x location of the ith element
y location of the jth element
x direction offset of the ith element (non-rectangular lattice)desired theta scan angle
desired phi scan angle
array grid angle
