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winson
Antenna Theory Regular

Joined: 12 Jul 2009
Posts: 16

 Posted: Mon Oct 25, 2010 9:45 am    Post subject: Gain of reflectarray antenna Hi everybody, I am trying to design a reflectarray antenna, so what are the design factors that affect the gain of the reflected far field beam? How do we able to design it so that the reflectarray will have higher gain? I was trying to read some books, but i can't find some related information about this matter. Any suggestion will be highly appreciate. Thank you.
Schubert
Antenna Wizard

Joined: 08 Apr 2009
Posts: 161

 Posted: Tue Oct 26, 2010 3:49 am    Post subject: What is a reflectarray? In general, to increase the gain, you must increase the efficiency or the directivity. Arrays typically have driven elements with high efficiency, so you have to increase directivity. Antenna Directivity can be increased with larger antennas (in general more directive than shorter antennas), or using an array with more elements (i.e., increase the net size of the array without introducing grating lobes), or use a sidelobe-minimizing weighting method.
winson
Antenna Theory Regular

Joined: 12 Jul 2009
Posts: 16

Posted: Wed Oct 27, 2010 4:39 pm    Post subject:

Reflectarray, if i not mistaken, is the combination of phased array and reflector antenna.

It was feed by a horn antenna and each array element (patches in this image) can have different reflection phase by vary the element's geometry.

Each signal path from horn antenna to reflectarray will have different path length.

 Quote: Antenna Directivity can be increased with larger antennas (in general more directive than shorter antennas), or using an array with more elements (i.e., increase the net size of the array without introducing grating lobes), or use a sidelobe-minimizing weighting method.

Can i know what is grating lobes and sidelobe-minimizing weighting method?

Thanks again.
Schubert
Antenna Wizard

Joined: 08 Apr 2009
Posts: 161

 Posted: Thu Oct 28, 2010 3:07 am    Post subject: Grating lobes occur if the elements are spaced too far apart (for uniformly spaced arrays, this can occur of the interelement spacing is larger than a half-wavelength): http://www.antenna-theory.com/arrays/weights/gratinglobes.php Sidelobe minimizing weights minimize the radiation pattern away from the main beam (the direction of peak radiation). An example, for uniformly spaced arrays is the dolph-chebyshev method: http://www.antenna-theory.com/arrays/weights/dolph.php
winson
Antenna Theory Regular

Joined: 12 Jul 2009
Posts: 16

 Posted: Sun Oct 31, 2010 11:21 pm    Post subject: Thanks for the information, Schubert!
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