Designing RF Antennas for Wearable Electronics and The

1 © 2014 ANSYS, Inc. May 9, 2014 ANSYS Confidential

Designing RF Antennas for Wearable Electronics and The Internet of Things (IoT)

Sudhir Sharma

ANSYS Corp.

Michael Schaaf

Synapse


Agenda

• Industry trends and key business initiatives

• Synapse case study

• Q/A


Market Driver: Our Need For Real-Time Information And Decision-Making

Wearable Technology

© Cisco

Internet of Things


Trend: Implications For High-Tech Industry

Miniaturization

• IC transistor features shrink to <20 nanometers

• Smaller form factor – from handheld to servers

Green and Reduced Power Consumption

• Increased power efficiency

• Regulation for reducing use of hazardous materials

Higher Speed and Broadband

• Designing for 100 Gbit per second channels

• Multiple wireless technologies within each product

Mobility and Platform Integration

• Voice, video, internet on single platforms

• More software and electronics in all industries


Initiatives: Focus Of High Tech Companies

Adopt System Engineering Approach

a holistic, multi-disciplinary and collaborative approach to

designing and maintaining complex systems

Optimize Power, Performance, and Cost

to deliver affordable high performance products for

mobile computing

Optimize Signal Integrity, EMC, & Thermal/

Mechanical

to reduce electromagnetic interference

Improve Reliability

to address increased structural, thermal and

electro migration challenges

Design Reliable Wireless Communication Systems

to deliver robust performance in complex surrounding

environment

Initiate Green Product Development

to comply with governmental regulations & market demands


Old Paradigms Single physics Testing Through Physical Prototypes Few Design Points Studied Compartmentalized Design and Verification

New Paradigms Comprehensive Solution • Electronics • Structural • Thermal Virtual Prototyping • Coupled physics • High-performance computing • Design optimization Collaborative • Electronic specification • Engineering knowledge

management

New Paradigm: Comprehensive Solutions


ANSYS HFSS simulation helped improve the design of body worn electronics

• 5X improvement in antenna range • 25% reduction in design cycle


Connect with me on LinkedIn: Sudhir K. Sharma

E-mail me directly: [email protected]

Explore our solutions for electronic simulation: www.ansys.com/high-tech

Follow us on social media: www.ansys.com/Social@ANSYS

Join us at booth #1413 at the Design Automation Conference, San Francisco

Further information:

mailto:[email protected]

http://www.ansys.com/high-tech



http://www.ansys.com/Social@ANSYS

9

9 May 2014 Synapse Confidential

SYNAPSE & ANSYS HFSS

WEARABLES WEBINAR

MIKE SCHAAF

10 9 May 2014 Synapse Confidential

ABOUT SYNAPSE PRODUCT DEVELOPMENT

Synapse helps leading companies deliver breakthrough experiences through

technology. Fueled by solving impossible engineering challenges, we develop

products that transform brands and accelerate advances in technology

www.synapse.com


WHAT SYNAPSE DEVELOPS

■ Connected Devices

■ Guest Experiences

■ Wearable Devices

■ Enterprise Software Solutions

■ Consumer Electronics

■ Health and Fitness

■ Transferable Tech

NIKE+ FUELBAND 2012-2013 VIABLEWARE RAIL 2012

PROPELLER SENSOR 2011 NIKE+ SPORTWATCH GPS

POWERED BY TOMTOM 2011

PANASONIC AVIONICS SYSTEM

(PROTOTYPE) 2009


WHAT DESIGNS LOOK LIKE


HISTORY OF ANSYS HFSS

Left: Press Release, October, 1990 Ansoft Corporation

ships the High Frequency Structure Simulator (HFSS)

for exclusive sale by the Hewlett Packard Company.

16 hours in 1990

3 seconds in 2007!

Below: Ansys has come a long way since then.


WHAT WE ARE TALKING ABOUT TODAY


WHY WEARABLES?

■ High value placement

■ More pervasive and less invasive

■ Speed of data assimilation

To generate the right data with sensors in the right place

and a way to view or share that data instantly.

Left: Google Glass kicked off the wearable tech trend. Middle: Sproutling, a San Francisco based startup, is developing

a new baby monitor. Right: Armour39® is a heart rate monitor that displays performance stats via mobile app and/or a

display watch.


WHY WEARABLES EXAMPLE


WHEN WILL WE HAVE THE TECH FOR IOT? NOW!


APPLICATIONS OF THE IOT

■ Mapping disease

● GPS, biometric vitals

■ Digital identification

● Unique biometric characteristics

■ Customization and control

● Proximity (GPS, BLE, NFC), interface

■ Human insight

● Collection and communication

of data

SENSORS + MACHINE-TO-MACHINE COMMUNICATION (M2M)


RF CHALLENGES WITH WEARABLES

■ Material selection based on

• Comfort

• Fashion

• Durability

• Allergens

■ Resistance to personal products

■ Waterproofing

Above: Instabeat Heart Rate Monitor

Above: News Headline, Allergic

Reactions Cause Fitbit To Recall Wrist-

worn Force Fitness Tracker


3 RF HEAVY HITTERS

Absorption Materials

Antenna Size

Above: Renderings of

a wrist band


RF NEAR THE BODY

■ Absorption because your a bag of

water

■ Comfort & size = movement

● S11 match shifts due to the influent of

the body

● Efficiency changes

■ Body movement

● Rotations causes gain variation

● Generally hurts the link budget

HUMAN BODY IMPLICATIONS

Bottom Right: S11

variation due to

movement

Top Right: Model of an

oscillating wrist


THE COMPLEXITY OF WEARABLES

■ Human body modeling

■ Size variations

■ Simulating movement

Low Resolution Medium Resolution High Resolution

(4 mm version) (2 mm version) (accurate version)


HUMAN BODY MODEL


THE SIMPLE WRIST


MOVEMENT OF THE HUMAN BODY MODEL


S11 VARIATION DUE TO MOVEMENT


WE THINK ABOUT USE CASE FIRST

Understanding your user

● How often does sampling need to

occur? (heart monitor & footfalls)

● User Interaction Rate

● Comfort

Drives the engineering

● Power

● Connection Interval

● Experience

● Connection Technology

● Link Budget

UNDERSTAND YOUR USER

Above: GPS Running watch example.


UNDERSTAND THE RF PROBLEM

Above: Currents in an antenna

Typical Frequencies


SIMPLE ARCHITECTURE WORKFLOW

ME/ID Concept

RF Concept


SIMPLE STARTING POINT


SIMULATION TIMES

■ Rapid development requires rapid sim times

■ Keep sims times less than an hour until CAD is final

■ Multi core license is well worth the money

■ We run large sims on remote machines

■ Small jobs are run on laptops

■ Cloud computing is also an option

■ Parametric sweeps and optimizations are typically run overnight

■ Analytical Derivative Function using Optimetrics to speed understanding of

design space


RAPID MODEL WORKFLOW

Above and Below: ME refinement


COMPLEXITY OF ORGANIC 3D MODELS

■ Developing 3D elements within curve

surfaces is extremely important

■ Simplify CAD and HFSS model to solve

quickly and allow rapid iterations

■ Imported CAD to modeled surfaces

increases solve times

■ There are several methods to simplify CAD

● Sweep simple geometric shapes based on

polylines

● Use HFSS meshing views to and controls to

reduce tetrahedron counts

● Use imported CAD and manipulate with CAD

simplification tool like SpaceClaim

Simplifying CAD


COMPLEXITY OF 3D ORGANIC SHAPES


MATERIAL SELECTION


SAME PAGE ENGINEERING


SENSITIVITY ANALYSIS

■ Sensitivity is some that needs to be verified throughout the project

■ Many real world factors conspire to reduce bandwidth

■ Many unintended modifications can cause shifts in the antenna resonance

point

■ The desire for rapid development can lead to missing elements that effect

the physical design

■ Informed knowledge of where short cuts can be taken is crucial

■ As in most RF generally, BW is protection against sensitivity

■ Wearable antenna design is a tradeoff between footprint and BW

● Small antennas tend to be narrowband

● We want to widen the BW while minimizing footprint


MP DESIGN / SENSITIVITY

■ Working element is ported into

Solidworks for ME interference checks

■ ME architecture generally requires

manufacturability changes affecting

RF antenna

■ ME CAD architecture is imported back

into HFSS and crossed checked with

RF design concept

WORKFLOW

ME import


CAD IMPORT


ALPHA LOCK

WORKFLOW

■ RF antenna sensitivity is finalized

■ Detailed RF verification and reaction

to ME changes

■ Typically begin generating prototypes


CHARACTERIZATION

■ S11 testing in the lab and in a Satimo

chamber validates design for mass

production

■ Environmental and sensitivity testing

validates design

WORKFLOW


SCRIPTING HFSS FOR SPEED

■ Trigonometric functions are more easily defined in a script

■ Scripting allows each 3D point to be broken into its constituent points

■ Trace widths, separation, height etc can all be parameterized easily

■ Parameterized models allow early rapid design space exploration

■ Parameterized models also enables later automated optimization

■ 3-Dimensional antenna concepts are difficult to parameterize

■ Python scripts offer a simple way to scale elements

● Number of elements in an antenna

● Fractal elements

● Number of turns in a coil


FLAT COIL PYTHON SCRIPT EXECUTION


WHY BOTHER USING SCRIPTS

+ Organization of complex values

+ Reuse

+ Minor changes provide major impact

- Script debug is difficult

PLUSES AND MINUSES


THE TAKEAWAYS

■ RF challenges and design considerations for the human body

■ Start early and sync often with your ME design team

● Rapid development requires parallel workstreams

● We need to be flexible in design to allow for ID material choices

■ How we leverage HFSS

● Scripting enables parameterization

● Parameterization enables rapid development

■ View the deck again at:

synapse.com/blog/post/ansys-hfss

■ Visit the ANSYS booth at DAC!

● Mike presents again June 2nd at 2PM

Documents

Designing RF Antennas for Wearable Electronics and The