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Microstrip antennas - Feeding techniques

Microstrip antennas - Feeding techniques. Presented By: Alejandro Fuentes 260725 Ricardo Pérez 260769. Undergrad thesis. National university of Colombia GMUN - CMUN group 2008. Conrad project and our project logos. http://gmun.unal.edu.co/cmun. Feeding techniques. Coaxial feed

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Microstrip antennas - Feeding techniques

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  1. Microstrip antennas - Feeding techniques Presented By: Alejandro Fuentes 260725 Ricardo Pérez 260769 Undergrad thesis National university of Colombia GMUN - CMUN group 2008 Conrad project and our project logos. http://gmun.unal.edu.co/cmun

  2. Feeding techniques Coaxial feed Coplanar feed Proximity coupled feed Aperture coupled feed Coplanar waveguide feed UNAL 2008  Page 2

  3. COAXIAL FEED UNAL 2008  Page 3

  4. Coaxial feed The inner conductor is soldered to the patch. Source: [1]. R. Garg, P. Barthia, I. Bahl and A. Ittipiboon “Microstrip antenna design handbook,” Artech House, 2001, pp. 17 UNAL 2008  Page 4

  5. Coupling UNAL 2008  Page 5 Excitation of the patch occurs through the coupling of the feed current density Jz to the Ez field. Coupling constant is:

  6. Modeling Source: [1]. R. Garg, P. Barthia, I. Bahl and A. Ittipiboon “Microstrip antenna design handbook,” Artech House, 2001, pp. 719–727 The coaxial feed can be modeled by uniform line current. Input impedance model is: UNAL 2008  Page 6

  7. Inductance compensation • Add a series capacitor • Electromagnetic coupling between the patch and the feed • The feed is terminated in a disk for increased coupling. Etch a concentric slot in the patch UNAL 2008  Page 7

  8. COPLANAR FEED UNAL 2008  Page 8

  9. Edge-coupled feed Source: [1]. R. Garg, P. Barthia, I. Bahl and A. Ittipiboon “Microstrip antenna design handbook,” Artech House, 2001, pp. 21 • It’s the basic technique for matching source and patch. • It’s necessary to set additional circuitry. UNAL 2008  Page 9

  10. Gap-coupled Source: [1]. R. Garg, P. Barthia, I. Bahl and A. Ittipiboon “Microstrip antenna design handbook,” Artech House, 2001, pp. 719–727 • The gap effect can be represented by shunt capacitor. • Requires a narrow gap width for efficient coupling. UNAL 2008  Page 10

  11. Inset feed Source: [1]. R. Garg, P. Barthia, I. Bahl and A. Ittipiboon “Microstrip antenna design handbook,” Artech House, 2001, pp. 719–727 Input resistance at resonance Feed position is selected for achieve a input impedance of 50 Ω. UNAL 2008  Page 11

  12. PROXIMITY COUPLED FEED UNAL 2008  Page 12

  13. Proximity coupled feed Electromagnetic coupling. Patch is on thick substrate (improve bandwidth). Feed line is on thinner substrate (reduce spurious radiations). Source: Balanis, C. “Antenna theory: analysis and design,” John Wiley & sons. 2th ed., chap. 14, section 14.1.2. UNAL 2008  Page 13

  14. APERTURE COUPLED FEED UNAL 2008  Page 14

  15. Aperture coupled feed Ground plane is between two substrates. Radiation from feed line doesn‘t interfere with radiation pattern of patch. Wider bandwidth. Source: Balanis, C. “Antenna theory: analysis and design,” John Wiley & sons. 2th ed., chap. 14, section 14.1.2. Source:Garg, Ramesh “Microstrip Antenna Design Handbook”, Artech House, 2001., Chap 1, section 1.3.4 UNAL 2008  Page 15

  16. COPLANAR WAVEGUIDE FEED UNAL 2008  Page 16

  17. Coplanar waveguide feed Coplanar waveguide is etched in the ground plane. a) Inductive coupling, b) capacitive coupling Mutual coupling between transmission lines are minimized. Source:Garg, Ramesh “Microstrip Antenna Design Handbook”, Artech House, 2001., Chap 1, section 1.3.5 UNAL 2008  Page 17

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