I think Hans is observing that when the elements are mounted in an insulated saddle on the sides of the boom, if you sight down the antenna from the end, the horizontal and vertical sets of elements don't cross at their centers. Rather, they cross about half the diameter of the boom, plus half the diameter of the elements, away from the element centers.
I think the answer is that this is just fine. Recall that a circular pattern can be created by having two completely separate antennas stacked side by side, 90 degrees in relative polarization, and fed with a phasing line. As long as the antennas are within some reasonable distance apart, the resulting pattern will be circular. I expect that being offset by such a small distance as the boom diameter will be of no consequence.
Hans, you have a good eye for details! Good question. Keep it up.
Greg KO6TH
Burns Fisher wrote:
I'm not an antenna designer, but I can tell you that the M2 LEO Pack crossed yagi elements go through the center of the boom (i.e. across the radius) and are insulated from it. They don't contact each other because they are offset from one another along the length of the boom. Of course the phasing lines have to be adjusted to deal with the elements being offset.
Is that what you mean?
73,
Burns WB1FJ
On Tue, Jan 15, 2019 at 8:16 AM Hans BX2ABT [email protected] wrote:
I'm sorry, but I wasn't complete in my description: I'm talking about yagis with the elements completely isolated from the boom with saddles (clamps) mounted on the boom to hold the elements in place. Much like the original LFA yagis are build. For an image go to my blog at bx2abt.com. --Hans
On 01/15/2019 03:12 PM, Hans BX2ABT wrote:
Should the elements of a RHCP cross yagi be centered at the boom, or should they be off center so that the middle of the H and V elements cross each other in the middle? My gut feeling says off center, but I'm not sure. I wonder how this influences the SWR. Cheers,
Hans
BX2ABT
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb