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Aperture Antennas

Aperture Antennas. INEL 5305 Prof. Sandra Cruz-Pol ECE, UPRM. Ref. Balanis Chpt. 12. Aperture Antennas. Most common at microwave frequencies Can be flushed-mounted We will analyze radiation characteristics at far field Rectangular aperture Circular aperture.

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Aperture Antennas

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  1. Aperture Antennas INEL 5305 Prof. Sandra Cruz-Pol ECE, UPRM Ref. Balanis Chpt. 12

  2. Aperture Antennas • Most common at microwave frequencies • Can be flushed-mounted • We will analyze radiation characteristics at far field • Rectangular aperture • Circular aperture

  3. Far field is the F of the near field t f • Fourier Transform for 1-D • For two-dimensions, x and y;

  4. Properties of Fourier Transform

  5. Taking the Fourier transform of the 2 equations above:

  6. Now, we define, And we obtain, Which has a solution of Then we take the inverse transform

  7. If z=0, then, we are at the aperture Which looks like: Which is the inverse of F…

  8. This is the Fourier transform for 2 dimensions, so: It can be shown that, Therefore, if we know the field at the aperture, we can used these equations to find E(r). =>First, we’ll look at the case when the illumination at the rectangular aperture it’s uniform.

  9. Uniformly illuminated rectangular aperture *Note: in Balanis book, the aperture is axb, so no 4 factor on the eq. above.

  10. How does this pattern looks…

  11. TE10 illuminated rectangular aperture

  12. Rectangular Aperture:Directivity • For TE10 illuminated Rectangular Aperture the aperture efficiency is around 81%. • For the uniform illumination, is 100% but in practice difficult to implement uniform illumination.

  13. Circular Aperture (Uniform illumination) • In this case we use cylindrical coordinates

  14. Circular Aperture w/ uniform illumination • For TE11 illuminated Circular Aperture the aperture efficiency is around 84%. • For the uniform illumination, is 100% but in practice difficult to implement uniformity

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