|Published on:||August 26th, 2019|
|With:||Eric Miller & Stefan O’Dougherty|
In this episode, your host and Co-Founder of PADT, Eric Miller is joined by Stefan O’Dougherty of FreeFall Moving Data to discuss the use of ANSYS simulation tools to drive the design of their unique RF antenna concept.
To learn more about FreeFall and see their product in action, click the link below and view the Wired article discussed in the interview portion of today’s episode: https://www.wired.com/story/new-space-telescopes-could-look-like-giant-beach-balls/
If you would like to learn more about what’s available in the latest release of ANSYS HFSS check out PADT’s webinar on the subject here: https://www.brighttalk.com/webcast/15747/361278
If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at firstname.lastname@example.org we would love to hear from you!
ANYSY HFSS provides many options for creating non-planar and conformal shapes. In MCAD you may use shapes such as cylinders or spheres, and with some steps, you can design you antennas on various surfaces. In some applications, it is necessary to study the effect of curvatures and shapes on the antenna performance. For example for wearable antennas it is important to study the effect of bending, crumpling and air-gap between antenna and human body.
One of the tools that HFSS offers and can be used to do parametric sweep or optimization, is “Draw equation based surface”. This can be accessed under “Draw” “Equation Based Surface” or by using “Draw” tab and choosing it from the banner (Fig. 1)
Once this is selected the Equation Based Surface window that opens gives you options to enter the equation with the two variables (_u, _v_) to define a surface. Each point of the surface can be a function of (_u,_v). The range of (_u, _v) will also be determined in this window. The types of functions that are available can be seen in “Edit Equation” window, by clicking on “…” next to X, Y or Z (Fig. 2). Alternatively, the equation can be typed inside this window. Project or Design Variables can also be used or introduced here.
For example an elliptical cylinder along y axis can be represented by:
This equation can be entered as shown in Fig. 3.
Variation of this equation can be obtained by changing variables R1, R2, L and beta. Two examples are shown in Fig. 4.
To make use of this function to transfer a planar design to a non-planar design of interest, the following steps can be taken:
A new wave port can be defined by the following steps:
Similar method can be used to generate (sin)^n or (cos)^n surfaces. Some examples are shown in Fig. 11. Fig. 11 (a) shows how the surface was defined.
Bending a substrate can change the transmission line and antenna impedance. By using equation based port the change in transmission line impedance effect is removed. However, the overall radiation surface is also changed that will have effects on S11. The results of S11 for the planar design, cylindrical design (Fig. 8), cos (Fig. 11 b), and cos^3 (Fig. 11 c) designs are shown in Fig. 12. If it is of interest to include the change in the transmission line impedance, the port should be kept in a rectangular shape.
Equation based curves and surfaces can take a bit of time to get used to but with a little practice these methods can really open the door to some sophisticated geometry. It is also interesting to see how much the geometry can impact a simple antenna design, especially with today’s growing popularity in flex circuitry. Be sure to check out this related webinar that touches on the impact of packaging antennas as well. If you would like more information on how these tools may be able to help you and your design, please let us know at email@example.com.
You can also click here to download a copy of this example.
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