design of log periodic antenna

This is what you want, I think..... you do not say what frequency range you want to cover................................

http://www.fortunecity.com/skyscrape.../LogCalc.html#

Hope this helps

Someone must have given a homework assignment to design a LPD antenna. There are a bunch of postings currently in play.

This applet is fine as far as it goes. Look at Smith's book for guidance for choosing sigma and tau.

LPD's are reasonably easy to design and model. Their strength is that they can be used over very wide frequency bands.