A HigherMode AnnularRing Patch Antenna With a PhotonicBandgap Ground Plane

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A Higher-Mode Annular-Ring Patch Antenna With a
Photonic-Bandgap Ground Plane

• Shun-Yun Lin
• Department of Electrical Engineering
• Cheng Shiu Institute of Technology
• Kaohsiung, Taiwan
• Email linsy_at_ema.ee.nsysu.edu.tw
• Kin-Lu Wong
• Department of Electrical Engineering
• National Sun Yat-Sen University
• Kaohsiung, Taiwan
• Email wongkl_at_ema.ee.nsysu.edu.tw

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OUTLINE

• INTRODUCTION
• Annular-ring patch antenna operated at TM21 mode
• Patch antenna with a PBG ground plane
• ANTENNA DESIGNS
• EXPERIMENTAL RESULTS
• CONCLUSIONS

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INTRODUCTION-1

• The resonant frequency
• of TMnm mode can be
• calculated by the mode chart
• As w/R is increased, the value
• of kR becomes less than n for
• a given mode
• When the ring width reach
• half the guided wavelength,
• higher order TMnm(n?0, mgt1)
• appear.

2w
R
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INTRODUCTION-2

• The typical radiation has a peak value at about
  35 away
• from broadside direction
• Both horizontal and vertical planes have conical
  radiation
• patterns
• The radiated power in azimuth plane is
  non-uniform

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INTRODUCTION-3
Patch antenna with slotted ground plane
Compact LP antenna
Compact DP antenna
Compact CP antenna
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INTRODUCTION-4

• Patch antenna with Photonic BandGap ground plane
  
• PBG structure is a periodic structure
• The forbidden bands are characterized by
• period of structure
• shape of the individual element of the lattice
• size of the individual element of the lattice
• Applied to antenna design
• isolation enhancement
• harmonic control
• gain enhancement
• impedance bandwidth enhancement

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ANTENNA DESIGN-1

• PBG ground plane
• A square lattice of 3 x 3
• circular slots are embedded
• The ratio of the slot radius
• to the PBG period is selected to be
• 0.25 to obtain optimum stopband
• depth and passband ripples
• The center frequency f0 of the
• stopband is determined from
•   f0 c/2S

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ANTENNA DESIGN-2

• Slotted ground plane
• Four circular slots are
• embedded in ground plane
• have the same radius and
• spacing as those embedded
• in the PBG ground plane
• placed in perpendicular
• to the surface current path
• of TM21 mode
• located almost under the
• annular-ring radiating patch

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EXPERIMENTAL RESULTS-1
Antenna with slotted ground plane
Antenna with PBG ground plane
Antenna with regular ground plane
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EXPERIMENTAL RESULTS-2

• The resonant frequency of the antenna with a
  slotted ground plane was greatly lowered
• The resonant frequency of the antenna with a PBG
  ground plane was slightly increased
• The impedance bandwidth for both antennas with
  the slotted and PBG ground planes are larger than
  the reference antenna

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EXPERIMENTAL RESULTS-3

• Good conical radiation patterns are observed for
  three studied antenna, especially for the antenna
  with PBG ground plane
• The radiation patterns of the antenna with
  slotted ground plane has smaller beamwidth

(a) Ref. Antenna at 2380 MHz
(b) Antenna with slotted GND at 1920 MHz
(c) Antenna with PBG GND at 2460 MHz
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EXPERIMENTAL RESULTS-4

• The studied antenna with slotted ground plane
• has a patch size reduction of about 35
• The studied antenna with PBG ground plane has
• a large F/B ratio of 12.1 dB

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EXPERIMENTAL RESULTS-5

• The antenna with a slotted ground
• plane has the largest peak antenna
• gain
• The gain variations of the antenna
• with a PBG ground plane is less
• than 0.5 dBi

Ref. antenna
Antenna with slotted GND
Antenna with PBG GND
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CONCLUSIONS

• Annular-ring patch antenna with a slotted ground
  plane
• Patch size reduced
• Impedance bandwidth enhanced
• Backward radiation increased
• Annular-ring patch antenna with a PBG ground
  plane
• Impedance bandwidth enhanced
• F/B ratio enhanced
• Small gain variations within the impedance
  bandwidth

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