There are numerous tools available to engineers in modern antenna design - but few combine flexibility and user-friendliness as effectively as Antenna Magus. The software allows specifications such as frequency, gain and bandwidth to be entered precisely and used to generate optimum design parameters. Developers can customize the dimensions and characteristics of antennas, which is particularly useful for applications such as horn antennas for millimeter wave communications.
Antenna Magus is used in a wide variety of fields, including
The significant time savings achieved by Antenna Magus are particularly impressive: Developers can fall back on proven designs, adapt them flexibly and export them effortlessly to the CST Studio Suite. There, advanced analyses and optimizations can be carried out, such as impedance matching, radiation patterns or efficiency.
The seamless integration of Antenna Magus with CST Studio Suite makes the entire development process more efficient and significantly reduces development time. This is illustrated by an example in which a horn antenna designed in Antenna Magus is developed and optimized for modern communication systems.
First, we design a pin-fed pyramidal horn antenna with Antenna Magus. Horn antennas are often used due to their high directivity, simple design and efficiency in the transmission and reception of electromagnetic waves. Especially in microwave and millimeter wave applications, they offer advantages such as a very high gain and a focused radiation pattern. The simulation of such antennas makes it possible to precisely optimize important parameters such as radiation pattern, impedance matching and efficiency. Horn antennas are widely used in satellite communication, radar and wireless communication systems. They are typically used in frequency ranges from a few gigahertz up to hundreds of gigahertz.
The directivity of a rectangular horn antenna, as specified in Balanis, is:
D≈7.5 (A/λ^2 ) Equation 1
Where are the aperture area and the wavelength. This formula is specific to pyramidal horn antennas, where the coefficient 7.5 comes from empirical analysis based on the geometry and radiation pattern of the antenna.
We develop a horn antenna with a center frequency of 100 GHz, a bandwidth of 10 % and a gain of 20 dBi. The antenna gain describes how effectively an antenna concentrates a signal in a certain direction compared to an ideal isotropic antenna.
In Antenna Magus, these specifications can be easily entered under "Frequency Band/s" and "Radiation Pattern", as shown in Figure 1. To specifically design horn antennas, we enter "Horn" in the "Keyword" window, which will display only matching horn antennas as options.
Figure 1: Entering the desired antenna properties in Antenna Magus
We then navigate to the Antenna Database of Antenna Magus and select the antenna type "Pin-Fed Horn Antenna". We check the available models and decide on a model that meets 98% of our requirements. So we start with a design that is very well adapted to our specifications.
In the new window, we enter "Port Impedance" as 50 Ω. Then, as shown in Figure 2, we press the 'Design' button.
Figure 2: Entering the "Port Impedance" and designing.
After a very short time, without a 3D simulation, the antenna parameters are calculated as shown in Figure 3 and are available under 'Parameters'.
Figure 3: The calculated geometric antenna parameters
The width of the aperture and the height of the aperture are Wa=13.38 mm and Ha= 10.45 mm respectively, therefore the area of the aperture is 139.82 mm². According to Balanis' equation 1, the gain for a horn antenna with an area of 139.82 mm² is 20.66 dBi, which is in good agreement with the desired gain.
In the final step, we press the "Estimate Performance" button, as shown in Figure 4, and after less than 2 minutes the design is completed.
Figure 4 "Estimate Performance" for calculation of electromagnetic antenna characteristics
All antenna properties, such as impedance and the 2D and 3D far-field curves, are available under "Estimated Performance". As an example, Figure 5 shows the resistance and gain curves as a function of frequency. As planned, at 100 GHz the resistance is 50 Ω and the gain is 20 dBi.
Figure 5: The resistance and gain curve of the horn antenna as a function of frequency
After the initial design with Antenna Magus, we can transfer the model to CST Studio Suite to run a full 3D electromagnetic simulation to verify and further refine our design. As shown in Figure 6, we select "Model Export" in the Antenna Magus ribbon, then "Model". We name the file and save it in .cst format.
Figure 6: Exporting the first design from Antenna Magus to the CST Studio Suite
The saved CST file is a fully parameterized 3D model ready for electromagnetic simulation. Figure 7 shows the model of the horn antenna with defined parameters. If desired, the solver settings or the geometric parameters can be changed. For the first 3D simulation, all values are kept and a time domain simulation is performed.
Figure 7: The model of the horn antenna in CST Studio Suite
The simulation time with CST Studio Suite is just over half an hour, as a full 3D simulation is performed here. Figure 8 shows the 3D far field of the horn antenna at 100 GHz with 20 dBi gain.
Figure 8. 3D far field of the horn antenna at 100 GHz with 20 dBi gain
The gain of an antenna describes the ability of the antenna to radiate or receive radio energy in a specific direction compared to an ideal isotropic radiator. This value is a theoretical value and is usually specified without taking losses into account.
The realized gain, on the other hand, takes into account additional losses that occur in the antenna, e.g. due to reflections, cable losses or mismatch losses between the antenna and the connected system. These losses reduce the efficiency of the antenna, which means that the realized gain is always less than or equal to the theoretical gain. For this pin-fed horn antenna, the realized gain is more than 3 dB lower than the theoretical gain because reflections and a mismatch due to a non-optimal matching of the connection between pin and waveguide reduce the gain. Figure 9 shows the realized gain of the horn antenna.
Figure 9: The realized gain of the horn antenna
CST Studio Suite offers the option of modeling the antenna more precisely using a 3D simulation. But that's not all: the antenna can also be optimized with regard to critical properties such as impedance, reflection and realized gain. The optimal position of the pin can be determined through optimization to achieve lower reflection and higher realized gain. The horn antenna design was optimized through a 3D simulation using the CST Studio Suite, adjusting the height and position of the pin to improve the previously non-optimal impedance matching. These changes led to a reduction in reflections at the pin port. Figure 10 shows the S11, reflection coefficient, at the pin port for both the original design and the optimized version. In the optimized design, the reflection at 10 GHz was reduced by approx. 14.7 dB.
Figure 10: S11 at the pin port for the original and the optimized design of the horn antenna at 10 GHz
After optimization, the realized gain of the antenna has increased to about 20 dBi. Figure 11 shows a comparison of the realized gain of the horn antenna before and after the adjustment and illustrates the improvements due to the optimizations.
Figure 11: Comparison of the realized gain of the horn antenna between the original and the optimized design
In this blog, we have shown how Antenna Magus can be used to design a horn antenna quickly and precisely according to the desired parameters. The design was then imported into the CST Studio Suite to further optimize the antenna through detailed 3D simulations.
The combination of Antenna Magus and CST Studio Suite offers decisive advantages: a fast development time, shortened simulation phases and an efficient design process that enables flexible adaptation and optimization of the antenna parameters. This approach sets new standards in antenna development - from conception to final optimization.