Transcript Slide - Uniserve Communications

IEEE Joint Communications Chapter - Vancouver
Ideas for Embedded Antenna Design
For Small-Size and Hand-Held Devices
Andrey Gleener
Andrey Gleener R&D Services Ltd.
[email protected]
http://mypage.uniserve.ca/~a8421/Andrey-Gleener/
Apple iPhone Antenna
Antenna close to on-board components
antenna developer has to extend design thought onto the whole
mechanical structure surrounding the Antenna
The Usual Antenna Properties:
• Frequency
• Bandwidth
• Radiation pattern
• Gain
• Efficiency
• Polarization
Technological Details:
• Materials
• Feed
• Mounting
Issues specific to Embedded Antenna:
• Interaction with Surrounding Circuitry
• Effects of Antenna Housing
• Interaction with Human Body
Types of structures used as embedded antennas
Helix
Loop
Monopole
Dipole
Slot
Inverted F
Patch
Currents forced
on Ground Plane
Currents localized
on Antenna Structure
Include Ground
Plane to get larger
effective
aperture
Avoid Ground
Plane if it is
excessively
lossy
Simple Embedded Antenna
Nordic Semiconductor
evaluation board
Pattern as function of total length
L =~ 1/2λ
E
L
L =~ 1λ
< 1/4 λ
Polarization is Important
E
~1/4 λ
~3/8 λ
~1/4 λ
E
PIFA
Planar Inverted F Antenna
PIFA from Monopole
Monopole
Inverted L
Inverted F
PIFA
PIFA from Slot Antenna
Slot
Half-Slot
PIFA
Advantages of PIFA
• can be matched directly to 50 Ohm
• high efficiency in compact form factor
• reduced coupling to surrounding environment
• low Specific Absorption Rate
• can be made resonant in desired multiple frequency bands!
Dual Band PIFA
Slot
Return Loss of Dual Band PIFA Antenna
6%
5%
Return Loss of modern multi band cellular Antenna
19%
21%
Mobile Phone Antenna Patterns
Patterns are not omnidirectional
Patterns are not optimal horizontally
Polarization is not entirely vertical
Proximity of User’s Hand and Head
further changes the pattern
Trends in Embedded Antenna development:
• Multi-Antenna systems
• Antennas with reconfigurable geometry
• Integration of multiple dissimilar Antennas in one enclosure
• Use of Metamaterials in Antenna design
Antenna and Circuit on the same board
Inside Linksys Wi-Fi Card.
Two Inverted-F Antennas arranged in diversity scheme.
PCB Material around the antennas removed.
Ericsson T 200 Antenna
Heat Staking the Antenna
Antenna Matched
Antenna Not Matched
• Antenna needs to be mounted specifically and precisely
• Antenna assembly must be highly repeatable from one assembly to another
• Antenna can not be loose or change position inside the package
• Any materials touching Antenna absorb energy
• Always verify that your Antenna is still matched when in production.