Broadband Antenna

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A broadband antenna means the antenna with wideband radiation characteristics. To make a broadband antenna, we can use a helical, a biconical, a sleeve, a spiral, and a log-periodic antenna.

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Broadband Antenna

  1. 1. Antenna Engineering CHO, Yong Heui Broadband Antenna
  2. 2. Bandwidth 1. Introduction <ul><li>Conventional definition </li></ul><ul><li>Fractional bandwidth </li></ul><ul><li>Traveling wave vs. standing wave (resonance) </li></ul>
  3. 3. Introduction 2. Helical antenna <ul><li>Helix </li></ul><ul><li>Operation </li></ul><ul><ul><li>Normal mode </li></ul></ul><ul><ul><li>Axial mode </li></ul></ul><ul><li>Coaxial line feeding </li></ul>
  4. 4. Normal mode 2. Helical antenna <ul><li>Small antenna </li></ul><ul><li>Small loop and ideal dipole </li></ul><ul><li>CP (Circular Polarization) for certain case </li></ul>
  5. 5. Axial mode 2. Helical antenna <ul><li>End-fire antenna </li></ul><ul><ul><li>The same phase on opposite side of a turn </li></ul></ul><ul><li>High gain antenna with lots of turns </li></ul><ul><li>Traveling wave: neglecting ground plane size </li></ul>
  6. 6. Introduction 3. Biconical antenna <ul><li>Variation of dipole antenna: thicker wire </li></ul><ul><li>Input impedance: dipole antenna </li></ul><ul><ul><li>Real and imaginary </li></ul></ul><ul><li>Discone (disk-cone) antenna </li></ul><ul><ul><li>LP (Linear Polarization) </li></ul></ul><ul><ul><li>Uniform azimuth coverage (omni-directional pattern) </li></ul></ul>
  7. 7. Cone type antennas 3. Biconical antenna  
  8. 8. Introduction 4. Sleeve antenna <ul><li>Sleeve: transmission and radiation </li></ul><ul><ul><li>Current on monopole and sleeve monopole </li></ul></ul><ul><li>Sleeve monopole and dipole </li></ul>
  9. 9. Introduction 5. Spiral antenna <ul><li>Frequency independent antenna </li></ul><ul><li>Self complementary antenna </li></ul>
  10. 10. Introduction 5. Log-periodic antenna <ul><li>Periodicity as the logarithm of frequency </li></ul>

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