# Need help understanding formula

Discussion in 'Mathematics and Physics' started by meriad, Mar 20, 2007.

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IU was hoping you may be able to help me with the following formula:

LANT = 0.2 × Length × ln(Length/d - 1.6) × 10-9 × k
Where:
Length is the total antenna length in mm.
d is the trace width in mm.
k is a frequency correction factor.
LANT is the approximate antenna inductance in Henry's

This formula is taken from the following datasheet:

http://www.electro-tech-online.com/custompdfs/2007/03/micrf102.pdf

My question is: What does 'In' stand for?

There appears to be no explanation for that variable.

2. ### dknguyenWell-Known Member

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ln (LN, pronounced lon) is the logarithmic function where the base is e. When ln is written, it implies base e. When log is written it implies base 10. Something like log2 or log5 (the # are subscript), it means the base is 2 or 5 respectively.

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So if I understand you correctly

I punch this into the calculator , I would take

0.2 × Length × 10-9 × k then pres exp button and the sum of ln(Length/d - 1.6)

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5. ### dknguyenWell-Known Member

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Yes. Have you not learned about logarithms yet? Or there just isn't a special notation for log base e where you are from?

EDIT: Just noticed you are from PEI! Well, I don't know if ln exists over there either. You never know.

6. ### bananasiongNew Member

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'ln' button is available on the scientific calculator right? If there is 'exp' button.

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Yes I've learned about logs, just it was about 15 years ago in Highschool, just wanted to make sure I remembered correctly....especially seeing as I couldn't find my 'log' bead on my abacus

8. ### dknguyenWell-Known Member

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THen upgrade to the slide-rule! 10x the processing power in a fraction of the space!

9. ### Nigel GoodwinSuper ModeratorMost Helpful Member

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Except the best thing you can say about a slide rule is it's an "educated guess".

10. ### Hero999Banned

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You can buy scientific calculators fairly cheaply nowadays, failing that just use the calculator on your PC - all modern operating systems come with one.