Antenna building questions
 

I am interested i building my own antennas like to start with a 2meter
dipole.
My questions is, say you have a plan that says to use 1/2 inch copper.
How do you know what will happen if you use thicker material like 3/4
inch tubing? Is there a formula that shows what the effect will be? Or
maybe efen smaller diameter? Or what if you use solid material instead
of hollow tubing.

What if you use the same diamter but a different material, such as
stainless steel instead of copper or aluminum instead of copper?
Please forgive these questions if they seem basic as I am a beginner.
My guess is the thickness of the element is not as important as the
spacing between elements but this only can be true to a point. I mean
for arguments sake what if you used large sewer pipe? I would guess
that would not work too well.

Yes there is a formula. Generally speaking the larger the diameter in
respect to the length, the shorter the antenna is overall. I dont
believe there is any difference between solid core and air core when it
comes to calculating the length. Types of material do have an effect but
in my experience you can ignore it.

The length is also affected by other nearby objects and ground. Your
feeding system (where the coax connects) can also affect it. Two
halfwaves in phase for example will tend to be shorter than one by itself.

You can also make a slot antenna. This is a sheet of metal with a
rectangular piece cut out and the feed at the middle at each side. From
memory these antennas need to have about 10% longer length than a
halfwave. A sewer pipe will also work fine.

You can certainly look up the formula on Google etc.

If you are building a simple dipole its not going to be too critical
anyway. For the diameters you specified I'd subtract maybe 1/8" as a
starting point.

Try experimenting!

Cheers Bob VK2YQA

wrote:
I am interested i building my own antennas like to start with a 2meter
dipole.
My questions is, say you have a plan that says to use 1/2 inch copper.
How do you know what will happen if you use thicker material like 3/4
inch tubing? Is there a formula that shows what the effect will be? Or
maybe efen smaller diameter? Or what if you use solid material instead
of hollow tubing.

What if you use the same diamter but a different material, such as
stainless steel instead of copper or aluminum instead of copper?
Please forgive these questions if they seem basic as I am a beginner.
My guess is the thickness of the element is not as important as the
spacing between elements but this only can be true to a point. I mean
for arguments sake what if you used large sewer pipe? I would guess
that would not work too well.