How to simulate your antenna? A simple introduction to MMANA-GAL
Note: This topic is not related to GALGAME (x
MMANA-GAL is a system based onMatrix methodThis is a software for simulating linear antennas, which originally started as a plugin for Black Cat System's MININEC tool (a company specializing in amateur radio software algorithms). It was written by German ham operators DL2KQ and DL1PBD using the BASIC programming language. Later, it was separated out into its own software. The free version (BASIC) allows us to analyze up to 10 kHz bandwidth, 600 feed points, and view 3D radiation patterns, gain ratios, impedance, and SWR values.
If Ham simply wants to experiment with creating (or designing) a DP antenna, a straight V-antenna, a reverse V-antenna, or a folded dipole, etc.Linear The software provides sufficient performance for antennas. If you want to study common parabolic antennas used in the GHz band, this program is not suitable; instead, please borrow HFSS/ticra grasp from an expert.
Download and install
MMANA-GAL-Basic It's only about 3MB in size, and despite its small size, it has all the necessary components. However, the software doesn't include Simplified Chinese. There are language packs available online that can be downloaded and placed in the specified directory; after restarting, you will see the option to select Simplified Chinese.
Open the program, and you will see four tabs: Structure, View, Calculation, and Far-Field Diagram. The steps for using this software are as follows:
1. In the "Structure" section, describe the coordinates of each resonator (in a three-dimensional Cartesian coordinate system) of your antenna, and specify where the feed point is located and what its load impedance is (if any).
2. Verify that the shape is correct in the "View" section.
3. In the "Calculate" section, specify the distance from the ground, operating frequency, and the software will begin to simulate. Alternatively, you can define an optimization goal, allowing the software to adjust certain structural parameters (length/diameter) to achieve optimal SWR.
4. To view more information in the "far-field diagram," such as polarization direction, impedance, SWR, and elevation angle.
Now, I will demonstrate this using a simple resonant design for a cross-shaped antenna in the 20m band (as proposed by friend BG5VCG).
Draw the structure.
This antenna consists of two orthogonal, half-wavelength dipole elements (or four arms, each 1/4 wavelength long), forming a "Z" shape parallel to the ground. This allows me to define a z=0 plane. Given that it resonates at 20 meters (or 14 MHz), each arm of the antenna is 5 meters long.
The smallest structure within MMANA-GAL is the "wire". Some wires that are electrically connected form a "unit". A unit can be a reversed V, a square box, or a triangle.
For the first oscillator, I treated it as a line segment within the space. Its endpoints had coordinates (0, -5, 0) and (0, 5, 0). This oscillator is called wire1.
The second oscillator is similar; its endpoint coordinates are defined as (-5,0,0) and (5,0,0), and it is referred to as wire2.
Regarding the dimensions, I assume a default of 4mm. In this case, I am using absolute length. If you have connected to the "wavelength" in the upper right corner, you need to use the ratio of λ to describe the length of the oscillator. When you connect the "connection point linkage", it will electrically connect the oscillators that cross each other (equivalent to mutual conductivity).
The bottom-left corner is the power feed point. In my case, since I haven't checked "link connection", both wires need to be powered. The "w1c" in this power feed point refers to the center of wire 1. If you want to power one end (e.g., an EFHW antenna), you can enter "w1e" to indicate "the end of wire 1". The voltage remains at its default setting, which doesn't matter.
As for the "automatic segmentation" DM1 DM2 SC EC, I don't know what those are either...
Confirmation view
There's not much to say about this; simply enter the correct coordinates in the "Structure" section, and a simplified representation of the antenna will appear. The red circle in the middle indicates the feed point. The z-coordinate is perpendicular to the ground.
Calculate and view far-field diagrams.
In the "Calculate" tab, we can set the dielectric constant (dielec) and conductivity (conduct) of the ground. There are some common tables available online that provide coefficients for various ground materials such as lawns, concrete, beach sand, metal plates, etc., allowing you to simulate these materials. For the 14 MHz band, I recommend a height of 2-4 meters. If operating below 10 MHz, a higher value is recommended. "Material" refers to the material of the antenna, which will affect the shortening factor due to skin effect and resistivity, thereby slightly affecting the final VSWR.
Remember to also fill in the target frequency. Once set, we can click "Start" and test it out. I tested twice (the second time changing the frequency to 14.05 MHz), and you can see that initially there is a slight capacitive reactance (jX is close to 0, but negative), followed by a slightly lower capacitive reactance closer to 0, which indicates that the frequency is indeed low. Adjusting the direction was correct. The resistance in the radiating part is close to 50Ω. Compared to the gain of the patch antenna, which is 5.98 dB, the front-to-back ratio is -1.84, and it's horizontally polarized. This can also be seen clearly in the far-field diagram. Overall, it forms a "pig's waist" shaped beam (when switching V+H display in the far-field diagram, you can see the superposition of beams in both polarization directions).
Advanced Usage:
If your antenna parameters are not ideal, you can consider optimizing them. The general process is as follows: set the optimization target (dependent variable). Here, you can use the mouse to drag the gain, VSWR, front-to-back ratio, impedance imaginary part, etc., numerical sliders. The left side of the slider represents the maximum value, and the right side represents the minimum value, while the middle represents 0 (for gain and front-to-back ratio). Alternatively, you can specify specific numbers using the "Detailed Settings" button.
Then, in the parameters section, you should add an object to select which axis (or dimension) of the coaxial cable/unit to optimize as a variable. The "capacitance matching" and "impedance matching" options are primarily used for tuning the SWR of Yagi antennas, and I'm not very familiar with using them (hesitant).
I don't think this is working well. If the cable is at an angle, it's impossible to scale the total length; you can only scale the coordinates of one axis.
Click "Start", and the software should be able to calculate the optimal result within a few seconds (and automatically modify the values in the "Structure" tab), you should then see the new SWR, impedance, etc. results under the current optimal conditions.
Other tips
You can quickly adjust the unit size in the Edit - Antenna Size menu.
After simulating in the "Calculate" tab each time, you can view the VSWR near the target frequency by clicking the "Frequency Response" button. Clicking "All Points" or "Detailed" allows for more precise simulation of the SWR curves on both sides. The "Z" tab also provides a clear visualization of changes in complex impedance.
When drawing transmission lines, if your antenna structure has common shapes (such as rhombus antennas, square frame antennas, or ring antennas), you can quickly add these structures using the "Unit Editor" menu, and then make fine adjustments to individual lines.
Additionally, MMANA-gal files can be saved with a .maa extension, making them easy to share and review.
Finally, I recommend the ARRL book "Classic Wire Antennas."
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