Optimization

  Automatically optimizes the antenna giving consideration to various parameters.   Select the Optimization in the view menu or push the Optimizationbutton in the calculation window to open the optimization window. The goals of the optimization are:
- Minimize the jX (get the antenna resonant)
- Minimize the SWR
- Maximize the gain
- Maximize the F/B ration
- Minimize the elevation of the beam
- Matching circuit
- Maximize or minimize the current

  In most cases, these parameters are in the 'trade-off' condition. You can select the parameters that you focus on using the slide bars in the top of the window. As you slide the bar to right, the selected target is prioritized. As you slide the bar to the left end, the target is ignored.

  If you check the No goal set box, MMANA-GAL simply sweeps the parameters regardless of the state of the slide bars. MMANA-GALincrements the parameter from the current value to the Max value. This is useful to observe the antenna behavior from the viewpoint of the height or frequency.

 Push the Advanced button to set the target at length. Assume that you are happy if the antenna has 20 dB F/B ratio. Put 20 in the F/B ratio box. MMANA-GALattempts to optimize the other parameters if the antenna already has 20 or more F/B ratio.

Push the Band setting button to get the dialog box, with which you can specify the band frequency and the source. This is useful for optimizing a multi-band antenna. In default, MMANA-GALtries only one band and source as specified.

  Matching circuit is one of the hairpin match, capacitance match, and any Z. The hairpin match has minus jX (capacitive) and the capacitance match has plus jX (inductive).

Current optimization attempts to maximize or minimize the specified pulse point.

The antenna parameters that MMANA-GAL changes during the optimization procedure are:
- Wire coordinate and radius
- Wire length, azimuth, and zenith (in polar coordinates)
- Element width, perimeter, and radius
- Parameters of lumped-constant load
- Antenna height
- Frequency
- Voltage and phase of the source
- Stack space

   You can set the parameters above as up to 128 variables. Hit return key or click on the type field to display the type selection pop-up menu. Hit return key on the what field to pop the menu up. Input a value manually to other fields.

Wire coordinate and radius

   These are most basic variables. You can change the X1, X2, Y1, Z1, Y2, Z2, and R of the wire. If the specified wire changes its coordinates, the connected wires also changes together to keep them connected. This method should be useful for the fine-tuning. Unit is always meter. Pos. is the element number.

 Wire length, azimuth, and zenith (in polar coordinates)

   You can change the wire length and angle with respect to the reference point in the polar coordinates. This is useful for optimizing the length or the angle of the inverted V and V beam. It should be noted that you must not set the element position or space as the variable if you change the X-axis. MMANA-GALdoes not prevent it but may not update the optimized results.
   When the coordinate of the wire is changed, the connected wire moves together with it. Pos. is the wire number. The step unit is meter or degree.

 Element

   The parameters that define the element can be set as the variable in the optimization. For a yagi antenna, for example, they are the element space, position, and width. For a loop antenna, they are space, positio, perimeter, etc. Pos. is the element number. Unit is always meter.

Lumped-constant load

   LC or R+jX can be set as the variable. If you want to change two loads in both ends of the element (e.g., loading DP or trapped yagi), you can use 'association function.' .   If both L and C are specified in the definition, MMANA-GALtreats them as a trap and keeps the resonance frequency unchanged. For example, if L is increased, MMANA-GALautomatically decreases C. Pos. is the number of lumped-constant loads. Unit of L is uH. Unit if C is pF. Unit of R is Ohm.


Antenna height

  Unit of the variable is meter.


Frequency

  Unit is MHz. If your target antenna is a multi-bander, do not use the frequency as the variable.

 Source

 MMANA-GAL changes the phase and voltage of the sources. Pos. is the number of source. Unit of the phase is degree. Unit of the voltage is V.

Stack space

  Unit is meter. If you set space in the what box, the vertical and horizontal spaces are changed at the same time.

Association

  If you put 0 to the association box, the parameter changes freely as an independent variable. If you put a plus number, it is assumed to have the same variable that the number points to. If you put a minus number, it is assumed to have the same variable negated that the number points to. You can put a simple equation, too. The operators supported here are +, -, *, and /. It works like a primary spreadsheet.

[Examples of association]
0    Not associated (independent variable)
1    Associated with variable 1 (the same value of variable_1 is put there)
-5   Associated with negated variable 5 (- variable_5)
1*1.05  Associated with variable_1•1.05 (variable_1 • 1.05)
2-1.5  Associated with variable2_-1.5 (variable_2 - 1.5)
-3+1.2  Associated with 1.2 - variable-3

   If you optimize the positions of the traps of a multi-band dipole, you should want to move two traps proportionally to the center of the antenna. You define two variables, Y1 and Y2, which specify the trap positions. The center of the dipole must be Y = 0. Define Y1 as an independent variable (association of Y1 = 0), and Y2 as Y1's negated value (association of Y2 = -1).   You can make use of the automatic association by right click at the variable box. MMANA-GAL makes a guess what should be the target of the association.   This method can be used to move the center wire of hentenna or tri-hat antenna.

   Pitch specifies the minimum step of variable change in either an absolute value or a percentage. Large pitch makes the convergence fast but will not reach the best result.

   Min and Max defines the range of the variable. The variable does not become smaller than Min or larger than Max. You could specify other variable with # followed by the variable number. If you put #1 in the Max box for example, the Max value is set the value of variable 1.

  If you do not put Max value to the element space of Uda-Yagi antenna, MMANA-GAL might give you much larger space than you expected. If you do not put Min to the width or perimeter, MMANA-GAL might shrink one of five elements of Uda-Yagi antenna and configure a four-element Uda-Yagi antenna as a result. It is a good idea to see how the antenna dimension is being changed in the antenna view window during the optimization.

   Push the Delete button to delete the variable where the cursor resides.

   Push the All element button to make MMANA-GAL add all the parameters to the optimization variable list. If the space check box is checked, the element space is used. If not, the absolute position of the element is used.

   Push the Element edit button to start an element selection view. Move the cursor to the variable that you want to vary in the optimization procedure, and push the OK button. MMANA-GAL registers the variable for the optimization. The variable marked with * is already registered. If you want to do this with the 3-D view, select the wire selection tab. Click the wire you want to add as a variable. Push the OK button. The wire already registered as a variable is shown in red.

   Step in absolute values: if checked, put an absolute value to the pitch. If not checked, put a percentage value.

   Resolution 2 degrees: MMANA-GAL calculates the beam pattern every 2 degrees. It shortens the calculation time, but degrades the accuracy particularly for the high-frequency antenna with a ground.

   Display log: the intermediate states of the optimization procedure are displayed in the log window.

   Push the Start button to start the optimization. Even during the optimization, you can see the wire definition, the antenna view, or the far field pattern in real time. Note that the MMANA-GAL is dedicated to the optimization; the response of the mouse should be very slow.

   Needless to say, MMANA-GAL works on the Windows operating system, so you can do another job even during the optimization. You could execute two MMANA-GAL at the same time. You can run the optimization in one window and design an antenna in the other window.

Optimization log

  The optimization routine would not always judge the result, which one thinks the best, is the best. This might be due to the fact that the rate of evaluation is different from that the designer expects.  You can read the optimization log by pushing the Optimization log button at the bottom of the Optimization window. It shows up to 128 latest steps of the optimization. You can select one of the steps and get it back to the optimization window so that you can manually pick out the optimization result you think best 

Tips on the optimization

     I have tried various optimization algorithms. I have figured out that the algorithm similar to the practical antenna adjustment, that is, changing one parameter at a time to maximize the target value and repeating it for other parameters as well, gives fast convergence and good results.
  This procedure, however, would not always give the real optimized solution that the one-by-one method gives. It could terminate the optimization just after finding a local minimum. If you are not satisfied with the result, change the parameter manually and retry the optimization.
   The result could depend on the parameter order. MMANA-GAL attempts the optimization by changing No. 1 parameter first and then does No.2 parameter. It is a good idea to put the most effective parameter in the first place of the variable parameter list.

   Pursuing the gain often results in the low impedance. The very low impedance makes the sustainable bandwidth narrow, and the wire loss cannot be ignored. It is difficult to implement the very low impedance antenna in the real world. Consider SWR in the optimization for obtaining reasonable results. 

   If you put two or more bands, MMANA-GAL attempts the optimization in each band and sums up the evaluation rates. Only the first feeding information is displayed.
  To keep the performance even in the band edge, put the band edge frequency as well. However, it increases the calculation time for the convergence. I am not sure if you could achieve good results.

  In case of  Uda-Yagi antenna, the moment method is weak in the calculation speed, so I recommend you use another analyzing tool that uses the electromotive force method.

Optimization goals

   - If your goal is Z
   Push Options menu, select Options and setup, click on the Setup tab, and input R and jX in the Standard SWR pane. Set the target to the SWR minimization and start the optimization.
Another way to this is: push Options menu, select Optimization, push Advance button, select Goal tab, check Optional Z, and put your R and jX. Set the target to the matching circuit and star the optimization. Do not set the target to SWR or jX.

   - If your goal is R
   Push Service menu, select Optimization, push Advance button, select Goal tab, check Optional Z, and put your R. Put * to jX. Set the target to the matching circuit and star the optimization. Do not set the target to SWR or jX.

   - If your goal is jX
   Push Service menu, select Optimization, push Advance button, select Goal tab, check Optional Z, and put your jX. Put * to R. Set the target to the matching circuit and star the optimization. Do not set the target to SWR or jX.

    - If your goal is to get the voltage fed antenna resonant
    Push Options menu, select Optimization, push Advance button, select Goal tab, check Optional Z, and put 10000 to R. Put 0 to jX. Set the target to the matching circuit and star the optimization. You may put a little value to jX. In case of the end-fed antenna, put * to jX.

Note: If you put * in R or jX, the marked value are not taken into consideration in the evaluation.

    - If your goal is beam pattern
    Push Service menu, select Optimization, push Advance button, select Environment tab, put 180 to Azimuth, and put 90 to Vertical. Set the slider bars of the Gain and F/B rates around the center, input your SWR, and start the optimization. 

    - If your goal is a broad band antenna
    Set two or three frequency spots as the bands in the Band setting window. It is recommended to minimize SWR rather than jX because R will not vary much (set SWR to the target beforehand).

    - If you want to keep the boom length
    Use the element position as a variable. Bear in mind that you have to keep the front-end and back-end elements fixed. In other words, you use the positions of the elements except for these two elements.
To automatically register the element position as a variable, you should uncheck the Distance from the active element box in the Edit element window. 

All elements button in the optimization

   When you push the All elements button in the optimization window, MMANA-GAL automatically uses the following parameters as variables: Loop length, space (or position), Width, length, X-width, space (or position).

MMANA-GAL analyzes the relative positions of the elements and assigns the variables in the order of the radiator, reflector, and directors (d1-dn).
  If two or more elements have the identical X-axis value, they are assumed to be connected. MMANA-GALmakes them associated. If an element has two or more variables in the width, length, and X-width, MMANA-GALasks the user how they should be treated (a dialog box appears).

MMANA-GAL does not automatically make association between the elements that have different X values. In such a case, right click on the optimization window to get the pop-up menu, select the element association. You can make association the element with the other element that have different X value. This technique would be useful for the antennas, such as a surface antenna, which has many elements in the same size and space.

  When you push the All elements button, MMANA-GALputs a typical value to the pitch. You may change the value as you like. The pop-up menu provides a means to give the identical pitch to the all variables.

  Resonance frequency of the element

  It should be useful for the antenna construction to have the resonance frequency of each element by using the antenna simulation. Put the source to the target element.   Set the frequency as the variable and set jX to the goad. jX = 0 indicates the resonance, so the obtained frequency is the resonance frequency.