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CST: Farfield Calculation of Antenna Arrays

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Katya047

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There is a option in CST in farfield plot called Array. It helps to predict farfield calculation of antenna arrays from your single element. I am using single patch to predict plot for 8 elements in vertical array.
Problem: When I doubled the amplitude(2A) for each antenna element the gain remained the same as was in single amplitude(A) to each antenna element.
Question:
1. As far as I know the total gain should increase with increase in amplitude to each element. Is this some issue of CST where it is re-scaling results or is it because of physics that I should know?
2. I want to understand the behavior of beam with change in magnitude to each element. Is there some pre defined pattern with change in magnitude?

Regards
 

juppydu

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There is a option in CST in farfield plot called Array. It helps to predict farfield calculation of antenna arrays from your single element. I am using single patch to predict plot for 8 elements in vertical array.
Problem: When I doubled the amplitude(2A) for each antenna element the gain remained the same as was in single amplitude(A) to each antenna element.
Question:
1. As far as I know the total gain should increase with increase in amplitude to each element. Is this some issue of CST where it is re-scaling results or is it because of physics that I should know?
2. I want to understand the behavior of beam with change in magnitude to each element. Is there some pre defined pattern with change in magnitude?

Regards
1. Wrong. Antenna directivity is a result of pattern integration, doubling the excitation does not change the antenna directivity, so what you see in CST is correct.
2. if you just scaling the coefficients the pattern does not change shape (see answer bove). If you have a amplitude taper (but you can also taper the phases) you can have a shaped beam.
 

Katya047

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Thanks Juppydu.
I came to know about amplitude tapering. Initially I am trying Taylor method.
Do you know about how amplitude tapering is done in LTE base station antenna. Someone told me SRS is used for calculation of amplitude weights but I couldn't understand it.
 

juppydu

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Sorry, I do not know the LTE base station antennas. If you play with Taylor shaping you will have a pencil beam with innermost side lobes below the specified level, is this what you are looing for ?
 

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