[TowerTalk] Wire log periodic antenna

[LA6FJA/K3RAG Stein Roar Brobakken]

Hi

I am planning to put a wire yagi for 40m to NA, but suddenly I came over a
picture for a wire log periodic antenna.


I have seen some pictures of wire log periodic antennas on internet  like
this one
http://www.antenna.it/military/images%20military/disegno%20lp1530-w%20copy.j
pg


One guy have made one like this
http://www.radiosky.com/super_cheap_log_periodic_antenna.html 
He have used spacing between 40 cm - 75 cm(2'5.8" - 1'3.8") for 17mhz -30
Mhz.


My spacing calculation gives:

40 cm is 1/35 wave on 17 Mhz, for first driver * is this optimal calculation
?

75 cm is 1/40 wave on 30 Mhz,? for Rear Reflector * is this optimal
calculation


so my question is then have anyone tried something like this version before?


My idea is to make one for 7 to 21 Mhz ?

should I just put my first driven element on 6 Mhz and then calculate until
21.5 Mhz for reflector?


I don't know what will happen when I get up one as Inverted-Vee in a Log
periodic formation ?

Anyone have a idea to figure the length of elements etc? correct spacing ?



73s Rag LA6FJA