Chip Antenna Mounting and Tuning Techniques

LTCC Chip Antennas –How to maximize performance

Antenna Mounting/Tuning PDF

Outline:

Chip Antenna Characteristics
Antenna Selection Considerations
Circuit Design Constraints
Layout Tips

Ultimate Goal → To Maximize Performance

LTCC Chip Antennas Chip Antenna Characteristics - 1

Features Ag radiating element encapsulated in ceramic.
A quarter-wave ( λ/4 ) monopole system.
Works with GND plane to form dipole system.
Certain “No-GND” metal-free space necessary.
Small form factor, thin profile & light weight

Chip Antenna Characteristics - 2

Omni-directional radiation.
Linear Polarization.
Mounting configuration flexibility.
Frequency range supported: 0.08 GHz thru 10 GHz.
WiFi, BT, WiMAX, UWB, GSM, CDMA, GPS etc.
Suitable for Pick & Place.

Antenna Selection Considerations - 1

Size
Frequency Band
Bandwidth
Polarization
Peak Gain
Average Gain
Radiation Pattern requirements

Antenna Selection Considerations - 2

Successful Antenna design means harmonious interaction of the “seven” parameters (next page).
Additional considerations for diversity systems – e.g. MIMO
Overall performance is always system dependent.

Circuit Design Constraints

Size of the Circuit board.
Layout of other board components.
Complexity of circuit.
Proper GND/No-GND dimensions and clearances.
“Tuning” Matching Circuitry
Shielding
Suitable Enclosure (material)

Layout Tips Note:
The ceramic chip antenna and top RF ground must be on the same plane. Substituting the top layer for an inner layer as a ground plane requirement will not work

Don’t put any metal objects or batteries (if applicable) above or below the yellow region.
Keep away any other metals from clearance area.

Layout Tips - 2

Layout Tips - 3

Layout Tips - 4

B. Measuring Steps

A. Antenna Matching Setup

One-port (S11) calibration for N.A. (Network Analyzer) Open-Short-Load for desired operating bandwidth
Mount probe (semi-rigid RF cable for our example) onto PCB and connect to N.A.
Measure S11 of test board without antenna or any matching components and save as: →S11_open →save trace to memory of N.A.
Measure S11 of test board with antenna and series 0Ω resistor mounted and save as: →S11_antenna
Set N.A. to data/memory mode (S11_antenna/S11_open) and display/save as: →S11_match
Match the trace of S11_match to 50Ω (center of Smith chart at the desired frequency)