When preparing for a business or personal trip, most of us want to check our travel routes in advance. There are many route-planning tools on the web today, and they help us to anticipate route difficulties such as heavy traffic, changes in street names, road sizes, accident locations, and many more. Some of these map applications even tell us what time we need to leave our starting location to reach our destination on time. Many of us end up “virtually” driving the route several times before we take the actual drive. Those virtual drives help us get from point A to point B in the shortest time possible, without unpleasant surprises.
Antenna system developers often face a similar challenge: We may have a great antenna design to get an RF signal from point A to point B in isolation, but the scattering environment around the antenna directly impacts the antenna’s ability to get the job done. So how do we anticipate the different routes that the signal might be forced to take to reach its destination? You guessed it—modeling and simulation of the antenna’s interaction with that environment.
The ANSYS HFSS SBR+ field solver provides the ability for antenna systems designers to model the antenna and its environment before the antenna is ever built or installed. Some of these environments can be quite large. For instance, modeling a WiFi router in a typical office environment to capture the effect of reflections, delays and blockage of the signal due to the physical features and materials in the office might involve modeling interactions that span more than 500 electrical wavelengths of distance. An extreme antenna-environment scenario might be the interaction of a 77 GHz automotive radar sensor with 300 meters of roadway and buildings, which adds up to an environment spanning 85,000 electrical wavelengths in size. That’s a large electromagnetic problem to solve!
Visual Ray Trace (VRT) for an antenna mounted on the tail of a helicopter taking off from the deck of a ship. Complete geometry shown at top, VRT at bottom shows the ray interactions between the antenna and the ship.
Handling antenna installation modeling challenges like this are a specialty for ANSYS, and are efficiently handled with our Shooting and Bouncing Rays (SBR) approach. With HFSS SBR+, the antenna design’s electromagnetic radiation is treated like an extended optical source, where we shoot a series of rays outward and observe the interaction of each with the environment. Rays that hit geometry lead to additional ray scattering. If we scatter enough of these rays, we develop an accurate representation of how electromagnetic fields propagate from our antenna through the environment, and how they are either scattered into space or are collected by a receiving antenna model located somewhere in our large, complex environment.
Visual ray trace for a 77 GHz radar coverage of a 120m length of empty roadway. Geometry (top) shows lights, lampposts and road structure. VRT (bottom) shows the ray interactions from a 77 GHz automotive radar position with the road scene structure.
HFSS SBR+ is complementary to the well-known finite-element meshing (FEM) used in the core HFSS solver. The HFSS FEM solver provides the ideal capability for optimizing an isolated antenna or array design, while the ray-tracing techniques employed in HFSS SBR+ are incredibly fast when you need to handle large-environment scattering and interaction impacts. Pairing these two powerful techniques yield a best-in-class platform for efficient design of the antenna and its performance in the real world in which it will be installed—all before you ever build unit #1.
In the ANSYS Electronics Desktop 18.2, the integrated HFSS SBR+ solver now provides a powerful pre-processing feature to show significant anticipated EM interactions posed by the environment: Visual Ray Trace (VRT). With VRT, you can visualize the direct paths taken by EM fields radiated by an antenna through an environment, giving insight into multi-path routes, causes of signal delay spread from one antenna to another, hot coupling zones for nearby antennas, shadowed zone locations and indirect radar scattering paths.
Need a roadmap to trace out the path taken by radiation through your complex environment? Trace it out, using the Visual Ray Trace (VRT) in the ANSYS Electronics Desktop before you build—and even before you simulate.
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