The elements are mounted approximately 3mm off the boom by nylon
insulator blocks on the original design.

The scaled design will use same construction.
http://www.qsl.net/dk7zb/start1.htm

Tom Ring wrote:
David wrote:

Hi,

I have a design for a Yagi antenna at 436MHz and would like to scale
it to 921 MHz. The calculations I used from the understanding I have
obtained from reading various articles appears below.

Would someone be kind enough to advise me if this procedure and values
look correct ?

Thanks in advance.

The original dimensions(mm) were

Boom = 15 or 20mm square aluminum, 350mm long

Element Length Spacing Diameter
RE 336 0 8
DE 316 80 10
D1 300 190 8
D2 292 330 8

My scaled values to 921MHz
Boom = 12mm x 12mm aluminum 166mm long

Element Length Spacing Diameter
RE 158.9 0 3.78
DE 149.5 38 4.73
D1 141.9 90 3.78
D2 138.2 142 3.78

Now I scaled the tubing to 6mm diameter that I have in stock
Element Length Spacing Diameter
RE 158.5 0 6
DE 148.7 38 6
D1 139.4 90 6
D2 135.3 142 6

Regards

David Huisman


Are these through the boom, and if so, insulated, or uninsulated?

If not through the boom, give specifics on the mounting.

Please do this for both the original antenna, and how you propose to
build the scaled one.

tom
K0TAR

--

Kind Regards

David Huisman
General Manager
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ORBIT COMMUNICATIONS Pty Ltd - Wireless Solutions that Work
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Website : http://www.orbitcoms.com
PO Box 4474 Lakehaven
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Phone: 61-2-4393-3627
Fax : 61-2-4393-3685
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David wrote:

The elements are mounted approximately 3mm off the boom by nylon
insulator blocks on the original design.

The scaled design will use same construction.
http://www.qsl.net/dk7zb/start1.htm


Ok, I'll try to run a scaled version for you in the next one or two days.

tom
K0TAR

Thanks Tom.

The smallest aluminum I have is 12mm square for the boom and 6mm round
for elements. I would like to stick with the aluminum rod as I think
this will be easier to secure than welding rod etc.

Tom Ring wrote:
David wrote:

The elements are mounted approximately 3mm off the boom by nylon
insulator blocks on the original design.

The scaled design will use same construction.
http://www.qsl.net/dk7zb/start1.htm


Ok, I'll try to run a scaled version for you in the next one or two days.

tom
K0TAR