[Antennas] FW: Feeding stacked antennas

[Jim Miller]

Subject: Feeding stacked antennas

 

How do I match four 50 ohm driven elements (in phase) to 50 ohm feed line?

 

For years I have been considering placing a 2 meter directional antenna into
my attic (because that is the only place where I can have one).  I find that
for 2 meters that the Moxon antenna would rotate between my roof braces and
possibly even a pair that are two Moxons wide.  I want to make it 2 tall
first and later add another pair alongside the first ones later.  The two
tall stack would be about 78 inches tall overall not including rotor and
that will fit in my attic.  Two over two would be separated by 19 inches(or
so) horizontally and still be 78 inches tall.  The driven element to
reflector would be about 11 inches so if carefully placed may also be able
to turn between my 24 inch spaced roof braces.

 

OK, so with the two Moxons vertically stacked, I would try the 75 ohm cable
to a tee and then 50 ohm to the shack for matching.  

 

The question, HOW do I feed the two over two stack and get to 50 ohms ????
If this isn't too stupid, can I just run all four together with same length
50 ohm coax or short ladder line pieces and then a 4:1 balun or toroid? 

 

I am excited with the modeling results (I am in Kindergarten on modeling) of
this and the small size and ability to rotate inside my attic to give me
gain and directionality.  I have had the modeling results for over three
years and only started to build a prototype in that time.  

 

I intend to build these two vertically very soon (weeks-month) but want to
double the stack in the future.

 

Comments please.

 

Thanks es 73, de Jim KG0KP