Presented by: John Lienau – RF Engineer

• Author Introduction

• LS Research – who we are and what we do

• Antenna Review – basic terms and common parameters

• Device Considerations

• Common Antenna Topologies

• Antenna Tuning

• Wireless Range

• LSR Overview

• Graduated from Marquette University 2008 with BSEE

• Graduated from Marquette University 2009 with MSEE

– Focused on Electromagnetic Theory, Numerical Techniques, and Antenna Theory

• Began at LS Research April 2010

– RF Design Engineer

– Antenna Design Engineer

• LS Research delivers turnkey wireless solutions with design services, RF

module solutions, manufacturing, and an on-site FCC / CE / IC approved

test facility.

• We are part of Texas Instruments’ Elite Design House program and MCU

and Low Power RF Developer networks.

• LS Research has over 30 years of proven wireless leadership with locations

in Cedarburg and Madison, WI.

RF Modules

Design Services

Testing Services

“It is easy to design a marginal performing antenna but

difficult to design a really good antenna”

The antenna can be the one of most daunting

components of RF design, it is the most important part

and yet often the last consideration.

The antenna makes it wireless!

• The antenna is a key component of a successful wireless design

• An antenna is simply a conductor by which electromagnetic waves

are sent and received from.

• An electrical signal from the radio induces a current on the conductor

which results in electromagnetic waves.

• The shape, size, and material of that conductor determine the

antenna characteristics.

• Size of the antenna is dependent on frequency!

• Depending on the antenna type, the size is between λ/4 and λ/2

• However, the shape of the conductor and material around it can

be used to shrink the antenna

– Shrinking the antenna, will reduces performance

Frequency l / 4 (in) l / 2 (in)

5 GHz 0.59 1.2

2.4GHz 1.2 2.5

915MHz 3.2 6.4

868MHz 3.4 6.8

433MHz 6.8 13.6

Wavelength (λ) = Speed of Light Frequency

• Your antenna has an impedance that is dependent on frequency.

• Impedance is controlled by antenna dimensions, matching

components, and nearby materials.

– The same antenna will have different impedances at different

frequencies!

• In order to have maximum power transfer between the radio and

the antenna, they must have matching impedance.

ZAntenna

ZRF Amp

Input Power

Reflected Power

• VSWR and Return Loss

characterize an antenna’s

impedance match.

• Voltage Standing Wave Ratio

(VSWR) is the ratio of the

voltage maximum to the

voltage minimum of the wave

waveform.

• Return Loss (S11): A measure

of how much energy is

reflected back by the antenna

due to mismatch.

1

1VSWR

1

1log20)log(2011

VSWR

VSWRS

dB

Antenna gain describes how well an antenna converts input power to radio waves.

isotropic

dipole dipole

Gain patterns are typically given in the principle plane of interest.

Power measurements are referenced to isotropic antenna (dBi) as a theoretical model for comparison with all other antennas

]/[

]/[;

4

srW

srW

P

U

U

Ug

t

rad

isotropic

radt

Gain patterns are like a balloon, the antenna designer can ‘push’ around power and shape the pattern as desired.

-30

-25

-20

-15

-10

-5

0

5

30

210

60

240

90

270

120

300

150

330

180 0

____ Total Gain (dBi) min: -18.7 max: +2.2 avg: -1.2

-30

-25

-20

-15

-10

-5

0

5

30

210

60

240

90

270

120

300

150

330

180 0

____ Total Gain (dBi) min: +0.5 max: +1.6 avg: +1.0

“It is easy to design a marginal performing antenna

but difficult to design a really good antenna”

• A 3 dB loss in antenna gain is equal to a loss of half the

TX power!

• Antenna gain affects both TX power and RX sensitivity.

• Antennas are one of the few electronic components that

cannot be adequately characterized on the lab bench

• Internal or external antenna

• Enclosure

– What is it made out of? Plastic? Metal?

– Where can the antenna be placed? Pick more than

one location!

– What will be near the antenna?

• How will the device be used? Who is using it?

– Mobile?

– Fixed?

• Incorporate antenna location into your design

process!

Distribution of

Current Magnitude

Charge

Accumulation

Current

Flow

Feed

Point

Voltage and Current at the feed will affect the impedance seen by the

transmission line

• Enclosure (dielectric loading)

• Human Body Loading (absorption & detuning)

• PCB Stack & Material (dielectric constant)

• PCB Ground Plane Size Important

• Just Like Real Estate: “location, location, location…”

• Cable and trace losses – avoid long runs to antenna

• Tune the antenna in its final environment

• Say NO to metallic enclosures, foil labels and metal flake paint

• Many different types

– Meander, F, Monopole

• Advantages and

Disadvantages

– Performance varies

depending on space

– Requires skilled

resources to properly

design

– Wide range of

performance – bigger is

always better

• Many different

combinations of wire

antennas

• Advantages and

Disadvantages

– Requires space in your

device

– May need mechanical

support

– Good gain and

bandwidth

– Precision in bending,

cutting, and placement

needed

• Many shapes and

sizes

• Advantages and

Disadvantages

– Can be complex and

very device specific

– Complicated to

manufacture

– Hand assembly

– Good gain and

bandwidth

• Chip Antennas

• Provide a small antenna

solution at the cost of

gain.

• Cheap and easy to

incorporate in the

manufacturing process.

• Directivity and gain

determined by PCB

• Often datasheets claim

much higher.

I’ve got my antenna! Am I done?

Nope. It’s time to put the antenna in

your product…

• The near field is related to

the current distribution on

the antenna

• Perturb the near field, you

change the current

distribution and vice versa.

• Critical to know the

electrical properties of

nearby materials.

– Conductive?

– Loss characteristics

Trace

F-Antenna

• ‘Matching’ refers to the use

of inductors and capacitors

to transform the antenna

impedance to 50 Ohms.

50 Ohm Output

From T-Line

1.0 pF

1.8 pF

4.3 nH

8.2 pF

Before After

• Range is dependent on the

environment your device

operates in.

• All object have unique

material properties that affect

the RF signal differently.

• Metal objects, cement walls,

water, have very negative

impact.

• ‘Line of Sight’ – no

obstructions between TX and

RX

• Office – lots of walls, cubes,

people

• Manufacturing - heavy

machinery, thick solid walls,

• Most datasheets state ‘Line of

Sight’ range

• Buildings are the most

unpredictable

environments

• You have no control

over how a consumer

actually uses your

device

• Plan for worst case

scenario

– Link Budget

• Floors 10-20 dB

attenuation, interior

walls 5-10 dB

• Indoor environments

produce many reflections

• Multipath will cause

additive and subtractive

interference.

• May eliminate nulls in

antenna pattern

100 200 300 400 500 600 700 800 900

-90

-85

-80

-75

RS

SI

dB

m

Sedona Module Performance

20 40 60 80 100 120 140 160 1800

50

100

Packer

Err

or

Rate

Sample Number

20 40 60 80 100 120 140 160 180

-90

-85

-80

-75

Avg R

SS

I dB

m

• Two antennas are better

than one

– Improve gain pattern

– Move out of nulls

• More expensive and

complex

• Antenna measurements need to be done in a location that:

1. Reflect no radiated energy

2. Is devoid of any outside RF energy

• Typically the measurements of interest include:

1. Measure the radiation pattern (See Above).

2. Measure the radiated power across the bandwidth of interest.

z

x

y

+ =

LS Research is a global leader in enabling advanced wireless technology platforms.

Start to finish, whatever the requirement, LS Research has the right solution.

• Design Services

– Wireless electrical / RF

hardware design

– Software design:

Embedded, FPGA, DSP

– Antenna simulation,

design, and testing

– EMC failure analysis

– Industrial Design

– Mechanical Design

– Turn-Key Manufacturing

• Testing Services

– EMC testing and radio

certification services:

FCC / IC / ETSI and

more…

– EMC failure analysis

• RF Modules

– TiWi-uB2™: Bluetooth ® /

BLE

– TiWi™: WiFi - Bluetooth ® /

BLE - ANT+

– ModFLEX™: 802.15.4 2.4

GHz and 900 MHz ZigBee -

6LoWPAN - proprietary

protocols

RF Modules

Design Services

Testing Services

• 802.11 a/b/g/n

• Bluetooth / BLE

• 802.15.4 / ZigBee / RF4CE

• NFC / RFID

• DECT

• 6LoWPAN

• ANT+

• Remote Keyless Entry 315/390/433

• Medical Implant Communications Service (MICS)

• <1 GHz, 2.4 GHz, 5.8 GHz, ISM

• White Spaces

• Mesh Networks

• GPS

LS Research is one of few facilities that can simulate, design, tune

and characterize antenna performance in real world configurations

all at the same facility.

– Complete antenna simulation

CST Microwave Studio 3D

Enclosure and antenna analysis

Body model simulations

– Network analyzer

– Anechoic antenna test chamber

Gain and antenna patterns on-site

• Antennas

2400 – 2483 MHz Dipole 2dBi for reverse polarity SMA

Dual band 2400-2500MHz, 5150-5850MHz Dipole

2dBi for reverse polarity SMA

902 – 928 MHz Dipole 2dBi for reverse polarity SMA

Select Chip Antennas

• Cable Assembly

U.FL to reverse polarity SMA bulkhead (female)

Antenna Shop Program Overview

Remove the guesswork!

Full complement of tools + experience

Match and optimize off-the-shelf solution or custom

design

Antenna examples include:

PIFA Patch Helical

Dipole Loop Slot

Monopole PCB Medical Implant

Program Overview

LSR has created 7 simple options to choose from to fit your antenna requirements

Program Overview

Option Cost Average

Duration

Antenna patterns on existing implementation $3,500 1 wk

Antenna match of existing implementation $6,800 1 wk

Antenna match of existing implementation (with patterns) $9,000 2 wks

Implementation of COTS antenna onto PCB $11,000 2 wks

Implementation of COTS antenna onto PCB (with patterns) $13,200 3 wks

Custom antenna design with defined enclosure $16,000 3 wks

Custom antenna design with undefined enclosure $22,000 4 wks

COMING SOON:

FlexAntenna Products

Provide companies with a more flexible antenna

platform

that requires less user design, and error in

implementation,

to ensure maximum antenna performance.

The initial platform of embedded antennas will

include:

2.4 GHz FlexPIFA

2.4 GHz FlexNotch

Features Include:

Adhesive mounting for accommodating of a

range of enclosure types and shapes

Tuned for plastic, metal and body worn

enclosures

FlexAntenna Overview