“Equation Based Surface” for Conformal and Non-Planar Antenna Design

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.

Equation Based Surface

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)

Fig. 1. (a) Select Draw -> Equation Based Surface
Fig. 1. (b) click on the icon that is highlighted

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.

Fig. 2. (a) Equation Based Surface window
Fig. 2. (b) Clikc on the “…” next to X and see the “Edit Equation: window to build the equation for X

For example an elliptical cylinder along y axis can be represented by:

This equation can be entered as shown in Fig. 3.

Fig. 3. Elliptical surface equation

Variation of this equation can be obtained by changing variables R1, R2, L and beta. Two examples are shown in Fig. 4.

Fig. 4. Elliptical surface equation

Application of Equation Based Surface in Conformal and Non-Planar Antennas

To make use of this function to transfer a planar design to a non-planar design of interest, the following steps can be taken:

  • Start with a planar design. Keep in mind that changing the surface shape can change the characteristics of the antenna. It is a good idea to use a parameterized model, to be able to change and optimize the dimensions after transferring the design on a non-planar surface. As an example we started with a planar meandered line antenna that works around 700MHz, as shown in Fig. 5. The model is excited by a wave port. Since the cylindrical surface will be built around y-axis, the model is transferred to a height to allow the substrate surface to be made (Fig 5. b)
Fig. 5. Planar meandered antenna (a) on xy plane, (b) moved to a height of 5cm
  • Next, using equation based surface, create the desired shape and with the same length as the planar substrate. Make sure that the original deisgn is at a higher location. Select the non-planar surface. Use Modeler->Surface->Thicken Sheet … and thicken the surface with the substrate thickenss. Alternatively, by choosing “Draw” tab, one can expand the Sheet dropdown menu and choose Thicken Sheet. Now select the sheet, change the material to the substrate material.
Fig. 6. Thicken the equation based surface to generate the substrate
  • At this point you are ready to transfer the antenna design to the curved surface. Select both traces of the antenna and the curved substrate (as shown in Fig. 7). Then use Modeler->Surface->Project Sheet…, this will transfer the traces to the curved surface. Please note that the original substrate is still remaining. You need not delete it.
Fig. 7. Steps for transferring the design to the curved surface (a)

Fig. 7. Steps for transferring the design to the curved surface (b)

Fig. 7. Steps for transferring the design to the curved surface (c)
  • Next step is to generate the ground plane and move the wave port. In our example design we have a partial ground plane. For ground plane surface we use the same method to generate an equation based surface. Please keep in mind that the Z coordinate of this surface should be the same as substrate minus the thickness of the substrate. (If you thickened the substrate surface to both sides, this should be the height of substrate minus half of the substrate thickness). Once this sheet is generate assign a Perfect E or Finite Conductivity Boundary (by selecting the surface, right click and Assign Boundary). Delete the old planar ground plane.
Fig. 8. Non-planar meandered antenna with non-planar ground

Wave Port Placement using Equation Based Curve

A new wave port can be defined by the following steps:

  • Delete the old port.
  • Use Draw->Equation Based Curve. Mimicking the equation used for ground plane (Fig. 9).
Fig. 9. Use Equation Based Curve to start a new wave port (a) Equation Based Curve definition window (b) wave pot terminal created using equation based curve and sweep along vector
  • Select the line from the Model tree, select Draw->Sweep->Along Vector. Draw a vector in the direction of port height. Then by selecting the SweepAlongVector from Model tree and double clicking, the window allows you to set the correct size of port height and vector start point (Fig. 10).
  • Assign wave port to this new surface.
Fig. 10. Sweep along vector to create the new wave port location

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.

Fig. 11. (a) Equation based surface definition using “cos” function, (b), (c), & (d) three different surfaces generated by this equation based surface.

Effect of Curvature on Antenna Matching

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.

Fig. 12. Effect of curvature on the resonance frequency.

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 info@padtinc.com.

You can also click here to download a copy of this example.

All Things ANSYS 037 – Optimizing the Industrial Internet of Things with ANSYS Digital Twins

 

Published on: May 20th, 2019
With: Eric Miller & Matt Sutton
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Senior Analyst and Lead Software Developer, Matt Sutton for a discussion on the industrial internet of things, and how ANSYS Digital twins helps companies make confident predictions about future product performance, reduce the cost and risk of unplanned downtime, and improve future product development processes.

If you would like to learn more about this update and see the tools in action, check out PADT’s webinar covering ANSYS Twin Builder here: http://alturl.com/ccjjq

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Discovery Updates in ANSYS 2019 R1 – Webinar

The ANSYS 3D Design family of products enables CAD modeling and simulation for all design engineers. Since the demands on today’s design engineer to build optimized, lighter and smarter products are greater than ever, using the appropriate design tools is more important than ever.

Two key tools helping design engineers meet such demands are ANSYS Discovery AIM and ANSYS Discovery Live. ANSYS Discovery AIM seamlessly integrates design and simulation for all engineers, helping them to explore ideas and concepts in greater depth, while Discovery Live operates as an environment providing instantaneous simulation, tightly coupled with direct geometry modeling, to enable interactive design exploration.

Both tools help to accelerate product development and bring innovations to market faster and more affordably.

Join PADT’s Simulation Support Manager, Ted Harris for a look at what exciting new features are available for design engineers in both Discovery Live and AIM, in ANSYS 2019 R1. This webinar will include discussions on updates regarding: 

  • Suppression of loads, constraints, & contacts
  • Topology Optimization
  • Improving simulation speed
  • Transferring data from AIM to Discovery Live

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Analyze, Visualize, and Communicate – What’s New With EnSight In ANSYS 2019 R1 – Webinar

Effective prototyping in today’s day and age requires not only an understanding of your product’s capabilities but also those of the environment it operates in, and how said environment impacts its use.

Engineers are finding that it is no longer possible to ignore the interactions between fluids and the structures that surround them, as they strive to optimize their product’s performance. 

EnSight helps you visualize coupled fluid-structure interaction data to gain the insights you need; providing a highly effective environment regardless of the complexity of the situation and the simulation being run. After exploring your data, EnSight can also be used to create a high quality visual representation to effectively communicate your results, thanks to the ability to place your model in immersive environments, add realistic lighting conditions, and so much more. 

Join PADT’s CFD Team Lead Engineer, Clinton Smith as we explore the capabilities of this tool, and take a look at what’s new in ANSYS 2019 R1, including updates on:

  • Parallel Fluent to Parallel Ensight capabilities
  • Transnational visual symmetry
  • EnVision handling of multi-panel display
  • And much more

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All Things ANSYS 034 – Celebrating 25 Years of ANSYS Simulation: Changes In The Last Quarter Century & Where The Future Will Take Us

 

Published on: April 8th, 2019
With: Eric Miller, Ted Harris, Tom Chadwick, Sina Ghods, & Alex Grishin
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by PADT’s Ted Harris, Tom Chadwick, Sina Ghods, and Alex Grishin, for a round-table discussion on their experience and history with simulation, including what has changed since they started using it and what they’re most impressed and excited by, followed by some prediction and discussion on what the future may hold for the world of numerical simulation.

Thank you again for those of you who have made the past 25 years something to remember, and to those of you who have come to know PADT more recently, we look forward to what the next 25 will bring.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Simulate Multibody Dynamics More Accurately with ANSYS Motion – Webinar

As mechanical systems continue to get more advanced and interconnected, there is an ever growing need for tools that can accurately analyze the impacts of various forces on the entirety of the system. Mechanical systems often contain complex assemblies of interconnected parts undergoing large overall motion, and thus require engineering simulation for optimal design.

Tools that produce multibody dynamics solutions are better able to account for these components and thus provide more accurate results quicker than running simulations of each component individually. 

One of the latest offerings from ANSYS Inc. is designed to do just that.

ANSYS Motion is a third generation engineering solution based on an advanced multibody dynamics solver. It enables fast and accurate analysis of rigid and flexible bodies and gives accurate evaluation of physical events through the analysis of the mechanical system as a whole. ANSYS Motion uses four tightly integrated solving schemes: rigid body, flexible body, modal and mesh-free EasyFlex. This gives the user unparalleled capabilities to analyze systems and mechanisms in any desired combination.

Join PADT’s Senior Staff Technologist, Jim Peters for a look at how this tool works, along with a deeper dive into its benefits and capabilities, including:

  • Multiple Advanced Toolkits
  • Various Application Areas
  • Accurate Boundary Conditions
  • Easy Interface with Other Software
  • Tightly Integrated Multi-body & Structural Analysis Solvers
  • And Much More

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All Things ANSYS 033 – Using ANSYS Simulation to Disrupt the World of Capacitor Technology

 

Published on: March 25th, 2019
With: Eric Miller & Sean Katsarelis
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by Sean Katsarelis form Polycharge for a discussion on how they leverage the ANSYS Startup Program and simulation tools to disrupt the world of capacitor technology.

Listen as they discuss the various capabilities and applications best suited for this market, along with updates on the worlds of PADT and ANSYS.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Mechanical Updates in ANSYS 2019 R1 – Webinar

From designers and occasional users looking for quick, easy, and accurate results, to experts looking to model complex materials, large assemblies, and nonlinear behavior, ANSYS Mechanical enables engineers of all levels to get answers fast and with confidence. 

With applications for everything form strength analysis to topology optimization, it’s no wonder this comprehensive suite of tools continues to serve as the flagship mechanical engineering software solution.

Impressive performance just got even faster with ANSYS Mechanical’s ability to run models with large contact areas up to 2X faster.

Join PADT’s Simulation Support Manager, Ted Harris for a look at this update along with what other new capabilities are available for ANSYS Mechanical, in the latest version; 2019 R1.

This presentation will feature exploration into updates regarding:

  • Linear Dynamics
  • Rigid Body Dynamics
  • Explicit Dynamics
  • Topology Optimization
  • Composites
  • And Much More

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All Things ANSYS 031 – Experience the Power of Simulation on the Cloud

 

Published on: February 25th, 2019
With: Eric Miller, Sina Ghods, & Judd Kaiser
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by Sina Ghods from the Simulation Support Team and Judd Kaiser of ANSYS Inc. for a discussion on the latest offering from ANSYS: ANSYS Cloud; a tool that allows you to take advantage of the speed and computing power of ANSYS simulation products, all without the need for expensive hardware. Listen as they discuss the various capabilities and applications for this new tool and share their excitement about what impact this will have on the world of engineering.

Want to learn more about what to expect in ANSYS Cloud? Check out PADT’s webinar covering everything you need to know about the tool’s latest update.

Watch here: https://bit.ly/2U7blzj

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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On-Demand Metal 3D Printing

Desktop Metal was created to change the way companies bring products to market with metal 3D printing. Current metal 3D printing is often too expensive or industrial for many potential users. Fundamentally different approaches were needed to offer a different way to produce metal parts for prototyping and in production.

That’s where Desktop Metal comes in.

Join us for an in-depth look at the Desktop Metal workflow from 3D model all the way to a finished printed part. For more information, visit our website here or contact us via email at sales@padtinc.com

Introducing ANSYS Cloud Compute – Webinar

Engineering simulation has long been constrained by fixed computing resources available on a desktop or cluster. Today, however, cloud computing can deliver the on-demand, high performance computing (HPC) capacity required for faster high-fidelity results offering greater performance insight.

ANSYS Cloud delivers the speed, power and compute capacity of cloud computing directly to your desktop — when and where you need it. You can run larger, more complex and more accurate simulations to gain more insight into your product — or you can evaluate more design variations to find the optimal design without long hardware/software procurement and deployment delays.

Join PADT’s Application & Simulation Support Engineer Sina Ghods for a look at how ANSYS is working to drive adoption by providing users a ready to use cloud service that offers: 

  • Reduced Turnaround Time
  • More Accurate Results
  • Access to More Complex/Larger Models
  • Secure Workflows
  • And Much More
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All Things ANSYS 030 – Updates Available in ANSYS Fluent 2019 R1

 

Published on: February 13th, 2019
With: Eric Miller, Tom Chadwick, & Sina Ghods
Description:  

In this episode your host and Co-Founder of PADT, Eric Miller is joined by Sina Ghods, and Tom Chadwick from the Simulation Support Team for a discussion on their favorite updates available in the latest release of ANSYS Fluent so far, followed by an update on news and upcoming events pertaining to PADT and ANSYS Simulation.

Want to learn more about what to expect in ANSYS Fluent 2019 R1? Check out PADT’s webinar covering everything you need to know about the tool’s latest update.

Watch here: https://bit.ly/2SJBFC4

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Introducing Additive to Automation with End-of-Arm Tooling – Case Study

In the factory of the future automation is king.

Manufacturers can drastically reduce lead times, reduce labor costs, and increase overall efficiency through the use of robotics at several stages in their workflow, each performing a different function. While each function serves a unique purpose specific to the task it will execute, they all utilize an essential component known as End-of-Arm tooling (EOAT).

Traditionally, companies that produce EOAT have used extruded aluminum, or machined aluminum frames, often making them heavy and cumbersome. One manufacturer however, has found a solution to reduce weight without sacrificing strength or durability, using 3D printing.

Download the case study to learn more about additive manufacturing’s place on the factory floor, and how you can use it to eliminate the need for heavy and overly complex parts.

Create parts that are 50% lighter, and designed based on your needs, not limited by your manufacturing process.

Download Here

Gone Skiing: Aerodynamics – Does It Matter Which Way Your Skis Are Pointing On Your Roof Rack?

I was on the gondola up at Keystone for night-skiing a week ago, after a long day at Beaver Creek, because the last thing I am going to do at 3:00 pm is try to make it back to Denver, as everyone knows it’s hardly more than a parking lot at that point. As it gets later, there’s nothing like a solo gondola ride, however, a solo ride would stop this story right about now.

On the gondola, I overheard a conversation where one gentleman was discussing how he was unable to open the hatch of his vehicle when his skis are in his roof rack. That’s fair, I know older WRX wagons with the spoiler would not be able to open with skis on the roof no matter what, so I figured that was the case. It turns out, that was NOT the case. The reason his hatch would not open was that he orients the skis with the tails forward because it is ‘more aerodynamic’ that way… I was skeptical, but held my tongue, knowing that I had the tools at my disposal to investigate!

I decided to make a model that would allow me to simulate various conditions to get to the bottom of this. My initial hypothesis is that the addition of the ski rack and crossbars is what has the largest effect on aerodynamics, and orientation of the skis probably has a negligible effect after that. As a side note, I am solely concerned with aerodynamics in this case, and am not worrying about the amount of the ski’s base material that is exposed for a given orientation. I am of the mindset that tree trunks and hidden rocks on the mountain are more of a danger to your bases than small rocks on the highway anyway. If you are waiting to comment, “Just get a roof box!”, I understand as I own both a box and a rack at this point, and they both have their advantages, and I will not be exploring the aerodynamics of a box…

…yet…

I was able to start by finding some faceted geometry of a Subaru Forester online (I’m from Colorado, can you tell?) and was able to import that into ANSYS Spaceclaim. Once in Spaceclaim, I was able to edit the faceted geometry to get nice exterior panel surfaces, which I then combined to get a single clean faceted exterior for the car.


Faceted Forester Geometry (Equipped with factory side rails)

After that, I used Spaceclaim to generate the remainder of the rack and skis, including crossbars, a ski rack, and a pair of skis (Complete with the most detailed bindings you have ever seen!). I made a combined part of the crossbars, rack, and skis for each one of my orientations, as this allows me to report the forces on each combined part during the simulation.


Added CAD geometry for the crossbars, ski rack, and a pair of skis

For the simulation, I used ANSYS Discovery Live, the newest tool from ANSYS that allows for instant and interactive design exploration. This tool lets me actively add my CAD geometry and shows results in realtime. I was able to start with just the car and then add and swap my ski/rack geometry with simple button clicks. With traditional simulation tools, I would have needed to create a mesh for each one of these cases, analyze them one at a time, and the post-process and compare results after the fact. After launching Discover Live, it’s as easy as selecting the type on analysis I want to run.

The various types of solutions that can be done in ANSYS Discovery Live. For the purpose of this blog, I am using ‘Wind Tunnel’

Once I have selected ‘Wind Tunnel’ for my solution, I can select my geometry, and then am prompted for the direction of flow, as well as selecting the ‘floor’ of my domain. Once that is done, results show up on the screen instantly. I only needed to modify the flow velocity to ~65 mph. I am most interested in the force on the faces of the combined crossbars, rack, and skis in each orientation, so I created Calculations for each one, which is done by simply selecting the part and using the popup toolbar to create the graph.

Popup toolbar allows for the quick creation of solution calculations

I was already off and running. I ran each one of the cases until the force plot had become steady.

Car Only
Skis Tips Forward Orientation

Skis Tails Forward Orientation

Seeing that the force results for the Tips Forward vs. Tails Forward cases were very similar, I decided I should also run a ‘Bases Up’ Orientation, even though I STRONGLY advise against this, as UV wrecks the base material of your skis/snowboard.

Ski Bases Up and Tips Forward Orientation

In addition to the contour plot shown in the images above, you can also use emitters to show streamlines and particle flow, which also give some pretty neat visualizations.

Streamlines shown on the Tips Forward orientation

Particle Emitter shown on the Tips Forward orientation

The graph plots show values for the Total Y Force for Tips Foward, Tails Forward, and Bases Up orientations to be 37.7 N, 39.1 N, and 37.1 N, respectively. Using Discovery Live, I was able to quickly run all 3 of these simulations, showing that there is not a major difference in the forces on the ski rack between the three orientations. So, put the skis on the roof in the direction that makes life easiest for you, and keep those bad boys paired to protect your bases from the sun, because splitting them isn’t going to help with aerodynamics anyway!

Next steps would be taking a specific case and running in 2D, then 3D, in ANSYS Fluent.

Fluent Updates in ANSYS 2019 R1 – Webinar

Computational Fluid Dynamics (CFD) is a tool with amazing flexibility, accuracy and breadth of application. Serious CFD, the kind that provides insights to help you optimize your designs, could be out of reach unless you choose your software carefully.

Experienced engineers need to go further and faster with well-validated CFD results across a wide range of applications, and with ANSYS Fluent users are to do just that; delivering reliable and accurate results.

Join Padt’s CFD Team Lead Engineer, Clinton Smith for a look at what new capabilities are available for the latest version of Fluent, in ANSYS 2019 R1.

This presentation will be focused on eight main sections, including:

  • User Interface
  • Preprocessing
  • Workflow Enhancements
  • Solver Enhancements
  • Transient Enhancements
  • Applications
  • Physics
  • Optimization

Learn how Fluent is the most effective tool for simulating fluid flow, various types of erosion, and much more.

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