Department of Engineering TechnologyTexas A&M UniversityCollege Station, TX

Microstrip Patch AntennaChristina LeeJames RitterDavid Lazaro

History___________________________• Developed in 1952, gained

popularity in 1974

• Primarily used in aircraft, missiles, rockets, mobile satellites, communication

What is a Microstrip Patch Antenna____•Using a circuit board to act as antenna

•At high frequencies, PCBs radiate signals

•Antenna engineers use this property

http://home.iae.nl/users/plundahl/antenne/patchant.htm

How it Works_______________•The patch resonates in one direction and radiates in the other

•The radiation portions are not part of the resonance

•Field width is constant

•The E-fields are out of phase but the currents are in phase

Characteristics: Local and Remote Mounting Directional Moderate to High Gain (6-15 dBi or Higher) Linear, Dual Linear, or Circular Polarized Very low to moderate cost

Antenna Specifications______________

Antenna Specifications______________Other basic characteristics: VSWR

Radiation Patterns

3dB Beamwidth

Or ½ Power

Gain

Polarization and Bandwidth

http://www.cwins.wpi.edu/wlans96/documents/wsh96_best.pdf

VSWR & Losses___________________Gain accounts for overall efficiency of antennaEfficiency is Affected by:

VSWR mismatch Ohmic Losses (energy lost as heat) Random Losses

http://www.cwins.wpi.edu/wlans96/documents/wsh96_best.pdf

Input Impedance___________________

Input Impedance vs. Frequency

Input Impedance of Microstrip Patch

http://cce.llnl.gov/eiger/tutorials/mstrip/

Radiation Patterns__________________MICROSTRIP PATCH ANTENNA RADIATION PATTERNS

Aperture Fed Patch Antenna @ 60 GHz

3D-Farfield plot, Gain 8 dBi

Examples________________________

http://www.ifn.et.tu-dresden.de/HF/hf/hfss.htm

                                    Comparison between calculated (green) and measured (red) return loss of small band Patch Antenna with shifted feeding point

Examples cont…___________________

http://www.ifn.et.tu-dresden.de/HF/hf/hfss.htm

Construction Details________________

Aperture Coupled

Co-axial Feedhttp://www.nt.tuwien.ac.at/mobile/staff/Alexander.Kuchar/thesis_linear_antenna_arrays/en/

http://home.iae.nl/users/plundahl/antenne/patchant.htm

Some Feeding Methods______________Edge fed

http://web.media.mit.edu/~martinez/downloads/MS_Thesis.pdf

http://www.q-par.co.uk/images/testpiece.gif

Some Feeding Methods cont…________Co-axial fed

http://web.media.mit.edu/~martinez/downloads/MS_Thesis.pdf

http://home.iae.nl/users/plundahl/antenne/patchant.htm

Some Feeding Methods cont…________Aperture coupled

http://web.media.mit.edu/~martinez/downloads/MS_Thesis.pdf

Disadvantages• Lightweight

construction• Versatility of

possible geometries• Low cost

manufacturing• Simplicity of

structure

Advantages• Narrow bandwidth,

typically 3%

• Have low directivity / broad beam width

• Low radiating power efficiency

http://www.orbanmicrowave.com/antenna_application_notes.htm

Even though MPAs have a narrow bandwidth, it can be increased.

• Increase the thickness of the board

• Increase the width of the antenna

http://www.orbanmicrowave.com/antenna_application_notes.htm

Real World Examples_______________

• GPS Antennas• Wireless LAN• Missiles• Rockets

http://www.eas.asu.edu/~trccomm/nsf/presentations/Feb_2_Salvatore_Bellofiore.pdf

Real World Examples cont…________

• Interaction between antenna and human body is less than external antennas

• Mechanically rigid and therefore does not break

• Does not increase overall size

Internal Integrated Microstrip Antenna

External Retractable Antenna

Internal Integrated Antenna

http://stewks.ece.stevens-tech.edu/EE683/TechArticles/mwjournal/article1/microanten.html

Real World Examples cont…_________

• Used at Johnson Space Center to measure pre-launch ice buildup on orbiter

• Measure thickness of ice on roadway

• Measure thickness of uncut coal in a mine

Microstrip Antenna as a sensor

http://www.nasatech.com/Briefs/May99/MSC22766.html

Questions?

Other References

• http://web.media.mit.edu/~martinez/downloads/MS_Thesis.pdf• http://ceta-mac1.mit.edu/pier/pier18/11.970723p.Yau.S.pdf• http://www.ctsystemes.com/zeland/publi/binoy.amv_8.pdf• http://www.ecs.umass.edu/ece/pozar/aperture.pdf• http://ee.eng.usf.edu/undergraduate/seniordesign/projects-sp01/oconnor.pdf• http://www.eagleware.com/home.html• http://www.thewirelessdirectory.com/Bluetooth-Development/Bluetooth-Antennas.

htm• http://www.egr.uh.edu/ael/documents/L&M_Orlan_99.pdf