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TUD
Antenna-Theory.com Newbie

Joined: 11 Feb 2010
Posts: 4

 Posted: Thu Feb 11, 2010 3:33 pm    Post subject: Far Field of Array with Parabolic Reflectors Dear All, if I have an array of 4 Parabolic Reflectors with elements spacing of 100lambda, where starts Far Field of this array? in the far field of each parabolic antenna or in the far field of array? thanks in advance.

Joined: 03 Jan 2007
Posts: 204

 Posted: Fri Feb 12, 2010 4:29 am    Post subject: The far field is where the radiation from each antenna falls off as 1/r^2 and the phase appears linear. Your application is quite odd, so you probably won't find the answer in a textbook. I actually think the exact answer is open to interpretation. But for me, the far field of that array is the region where you are in the far field of each antenna. This means the far field region will not be a simple region, but one with holes centered around each antenna. The very conservative answer is you should be in the far field assuming the antenna is the size of the array, but I think the array will act like an array even between the elements, given the large spacing.
TUD
Antenna-Theory.com Newbie

Joined: 11 Feb 2010
Posts: 4

 Posted: Fri Feb 12, 2010 12:28 pm    Post subject: Thank you for your answer. For example, if we take reflect array. In the far field formula "D" is a maximum dimension of an array (the largest side of array) and it doesn't matter if the size of the patch is equal to the cell size (fit in the cell) or is smaller than the cell. If smaller we have also "holes" but this fact doesn't play any role for the far field calculation. but the difference is that the patches reradiate the received power and the parabolic antennas only reflect it and dont reradiate. I don't know, does this difference play a role for the FF calculations?
Schubert
Antenna Wizard

Joined: 08 Apr 2009
Posts: 161

 Posted: Tue Feb 16, 2010 5:52 am    Post subject: Your comment: "ut the difference is that the patches reradiate the received power and the parabolic antennas only reflect it and dont reradiate. " - doesn't make any sense.
TUD
Antenna-Theory.com Newbie

Joined: 11 Feb 2010
Posts: 4

Posted: Tue Feb 16, 2010 7:56 am    Post subject:

 Schubert wrote: Your comment: "ut the difference is that the patches reradiate the received power and the parabolic antennas only reflect it and dont reradiate. " - doesn't make any sense.

Do you mean that there is no difference?
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