Yagi element diameter question

[roadrunnernm]

Hello All, 

 

I have read that increasing the diameter of yagi elements will broaden the usable bandwidth. 

 

If the diameter is increased is the spacing changed?  That is to say, is the spacing measured from the center of an element to the center of the next? or from edge to edge?  Taken to the extreme (unlikely I understand) the elements could be close to touching.  Or is there a point of diminishing returns?  Say larger than one inch diameter or so?

 

Thanks for your help and patience. 

[Guest spd641]

Hello All, 

 

I have read that increasing the diameter of yagi elements will broaden the usable bandwidth. 

 

If the diameter is increased is the spacing changed?  That is to say, is the spacing measured from the center of an element to the center of the next? or from edge to edge?  Taken to the extreme (unlikely I understand) the elements could be close to touching.  Or is there a point of diminishing returns?  Say larger than one inch diameter or so?

 

Thanks for your help and patience. 

Good question,

I really do not have the answer to that but we do have a few that do have the knowledge and hopefully someone like JohnE will answer this question for you...William

[JohnE]

you might want to have a look at this. my knowledge of building antennas is limited but as far as I know bandwidth is a function of length, diameter would be power handling.

http://tf.nist.gov/timefreq/general/pdf/451.pdf

http://vhfdx.radiocorner.net/docs/JANqx00.pdf

[zap]

Bandwidth is a function of element thickness. Usually length is decreased a little as well.

 

I can't think of any Windows programs off the top of my head. A really good one (runs off of DOS though) is YagiMax. It lets you model different designs, element thicknesses, spacing, etc. 

 

General antenna gain/bandwidth rule, higher gain=less bandwidth.