Elements of a YAGI Antenna

[big420dog94550]

I have built a 2.4ghz wifi yagi antenna. Based on all the designs Ive seen, the elements of a yagi are insulated from each other and insulated from the beam they are mounted to. Yet I bought a 2.4ghz wifi yagi and all elements that mount to the beam are all made of aluminum and are not insulated by any means from each other. They seem to actually be crimped in a way, to each other... So help me out here.. Are they or are they not supposed to be insulated/ isolated from each other?

 

[prcguy]

The very center of a 1/2 wavelength element as used in a Yagi is at or near zero ohms impedance, so the center can be grounded to a metal boom, or floating and insulated with no change in performance. The element length calculations will be slightly different for grounded or floating elements.

For a commercially made antenna it will be easier to mfr and stronger if the elements are welded to a metal boom. For home made antennas it might be easier to fabricate by using an insulating material for the boom and floating the elements, especially at 2.4GHz where a millimeter change in element length or metal boom diameter can make a difference.

I have built a 2.4ghz wifi yagi antenna. Based on all the designs Ive seen, the elements of a yagi are insulated from each other and insulated from the beam they are mounted to. Yet I bought a 2.4ghz wifi yagi and all elements that mount to the beam are all made of aluminum and are not insulated by any means from each other. They seem to actually be crimped in a way, to each other... So help me out here.. Are they or are they not supposed to be insulated/ isolated from each other?

 

[big420dog94550]

that makes a lot of sense. so how much difference in element length do you think there is between a grounded system over a insulated one?

 

[prcguy]

Depends on a lot of things. If your talking a 2.4GHz Yagi with a 1" dia metal boom, and 1/4" dia elements. they will be much shorter in fractions of a wavelength than the same design using an insulated boom and 1/32" dia elements. For a similar design at 100MHz using a 1" dia boom the differences will be much less in fractions of a wavelength.

Most Yagi calculator programs allow you to enter boom material type, boom dia and element dia plus straight or tapered elements to compensate.

that makes a lot of sense. so how much difference in element length do you think there is between a grounded system over a insulated one?