[TowerTalk] Wire log periodic antenna

[n8de at thepoint.net]

Rag,

The spacing between adjacent elements in a LPDA is NOT a function of  
highest/lowest frequency.

Do some research on LPDA design and you will discover that the  
'graduation' of spacing and element lengths is dependent on CHOICE of  
'sigma', the factor which determines bandwidth and boom length.

When Dr. Duhamel of Collins Radio 'discovered' Log Periodics waaaaay  
back, his design information was published in a few texts, but most of  
it goes too far for ham radio uses.

K4EWG {I believe] designed and built a nice LPDA that was printed in  
the ARRL Antenna Handbook and one edition of the Antenna Compendium.

A little searching should prove fruitful.

Good luck.

Don
N8DE

Quoting LA6FJA/K3RAG Stein Roar Brobakken <s-roabr at online.no>:

> With correct picture link !!
> 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,
> Just 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
>
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