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Double Quad

Here is a discription of a 9 dBd double quad and its calculations

L = 0,6 lambda -> this shood be considered a minimal length and can be longer.
h = lambda -> this shood be considered a minimal lenth and can be longer.
x = 1/4 lambda
d = 1/8 lambda
connector can be of any type. it is prefered to have semirigid directly attached to it:

If you bought a bend one like me, be extremely carefull to straighten it. I told the seller that I did not want this because I want a straight one. The seller said just bend straight again like this. The seller took the semirigid and showed me how. And he broke it!

13 cm example

L = 8 cm
h = 13 cm
x = 3,3 cm
d = 1,6 cm

23 cm example

L = 16 cm
h = 23 cm
x = 5,8 cm
d = 3,2 cm

There are many ways to connect the semirigid to the reflector. If the reflector is cupper it could be soldered.

Good luck building!