How to design log periodic antenna

hope this helps. from the ARRL handbook. LPDA antenna design

https://rapidshare.com/files/431566370/10.pdf

I understood procedure but not still clear about spacing between feeder, whats the equation for spacing to find.?

I'm designing a printed LPDA, my question is how to choose the width of the antenna boom? is there any formula or relation between boom width and the widths of the dipoles?

this software design LPDA antenna

this program is for the conventional LPDA antenna. I need some design equations for calculating the widths of dipoles and the boom of the antenna.

this software calculate the boom and widths of antenna

dear friend
on your design you have toe , sigma and R........toe 0.8-0.95 sigma 0.05-0.2 R 50 or 75 ohms
first- calculate za =60 ln{ (16 k toe sigma)/[pi (1+toe)]}
k is average ratio of elements LENGTH to DIAMETER.for better resault you may slim elements to be constant k.
ln is natural logarithm.
second- x={R(1+toe)/(32 sigma toe za)}
zo=R[x+square (x power2 +1)]
zo is the characteristic impedance of boom line.
if you use round tube diameter d and distance between centers D....zo=276 log (D/d)
if you use square tube side a equivalent diameter is 1.06 a
so if you choose tube you will find separation between them.you are free to ask more. juji tabrizi

---------- Post added at 07:11 ---------- Previous post was at 06:12 ----------

dear friend
on your design you have toe , sigma and R........toe 0.8-0.95 sigma 0.05-0.2 R 50 or 75 ohms
first- calculate za =60 ln{ (16 k toe sigma)/[pi (1+toe)]}
k is average ratio of elements LENGTH to DIAMETER.for better resault you may slim elements to be constant k.
ln is natural logarithm.
second- x={R(1+toe)/(32 sigma toe za)}
zo=R[x+square (x power2 +1)]
zo is the characteristic impedance of boom line.
if you use round tube diameter d and distance between centers D....zo=276 log (D/d)
if you use square tube side a equivalent diameter is 1.06 a
so if you choose tube you will find separation between them.you are free to ask more. juji tabrizi