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How can I find direction of the main beam of an antenna if antenna has radiation intensity as following?
$$U=[\dfrac{sin(5\pi cos\theta)}{10sin(\pi cos(\theta/2))}]^2$$ Where $$0<\theta<\pi$$
My first trial is to find the places where derivatives equal to zero. But the results also give places of the nulls. So, how should I distinguish themain beam between the all nulls (zeros) and sidelobe peaks (local maximas)?
But the results also give places of the nulls. So, how should I distinguish themain beam between the all nulls (zeros) and sidelobe peaks (local maximas)?
Use your favourite spreadsheet and produce a graph then you get all your information together. The formula is not hard to use in (say) excel.
By evaluating U at the local extrema you found, as well as the endpoints of the domain, and picking the one with the highest value. No fancy tricks.
