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High Gain Antenna

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A high gain antenna is the antenna with very high antenna gain. We can consider antenna gain as concentration ratio of input power. Using Yagi-Uda array, traveling wave, aperture, and parabolic reflector, we can design a high gain antenna.

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High Gain Antenna

  1. 1. Antenna Engineering CHO, Yong Heui High Gain Antenna
  2. 2. Introduction 1. Yagi antenna <ul><li>Yagi-Uda antenna: parasitic array </li></ul><ul><li>1926 at Tohoku University, Japan </li></ul><ul><li>End-fire traveling-wave antenna </li></ul> Yagi antenna: one source
  3. 3. Operational principle 1. Yagi antenna <ul><li>Reflector, driver, and director </li></ul><ul><li>Input impedance: capacitive or inductive loading </li></ul><ul><li>Gain: about 10 dBi </li></ul>
  4. 4. Introduction 2. Traveling wave <ul><li>Traveling-wave long wire antenna </li></ul><ul><li>Beverage antenna (wave antenna): Harold H. Beverage in 1922 </li></ul><ul><li>Traveling-wave vee antenna </li></ul><ul><li>Rhombic antenna </li></ul>
  5. 5. Radiation pattern 2. Traveling wave <ul><li>Input impedance: almost real </li></ul><ul><li>Traveling wave: surface wave and leaky wave </li></ul> Rhombic antenna
  6. 6. Introduction 3. Aperture antenna  <ul><li>Horn antenna: sectoral horn, pyramidal horn, conical horn </li></ul>
  7. 7. 4. Reflector antenna Parabolic antenna  <ul><li>Symmetric mounting </li></ul><ul><ul><li>Masking effect: aperture blocking and diffraction </li></ul></ul><ul><ul><li>Spillover: ground noise </li></ul></ul><ul><li>Offset mounting </li></ul><ul><ul><li>Small antenna: 1 ~ 4 m (diameter) </li></ul></ul><ul><ul><li>Spillover: ground noise </li></ul></ul><ul><li>Cassegrain mounting </li></ul><ul><ul><li>Parabolic and hyperbolic reflectors </li></ul></ul><ul><ul><li>Spillover: sky noise </li></ul></ul>
  8. 8. 4. Reflector antenna Cassegrain antenna 
  9. 9. Introduction 5. Array antenna <ul><li>Antenna gain vs. loss </li></ul><ul><ul><li>: number of elements </li></ul></ul><ul><ul><li>: distance from feeder to element </li></ul></ul>  Array antenna

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