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Hi m8,


I know what you intended to do, you tried to help other forum members wich is appricated! Therefor my answer was only there to let you think.


But ill be more clear.

If you have problems to insert things in eznec, no worries..we all have.. a helping hand migthbe the solution. What you shouldn’t do is make a model and provide "proof"which because of the lack of input can be false.

You mention "here are the results of the antron and it is "ill" effected etc.


If you would have done things right you would have noticed the beam acts as a groundplane and the “strange” high angle elevation lobs would change of the antron.

How can you be surprised of the results and take your conclusions of a input which isn’t a replica of what is actually going on?

You intentions of only producing the model to see “if it could be done” seems the opposite of what is written above.


Now, we seem to have “conclusions” like: “it is negligible” etc. : You mention that it is no way this was intended to duplicate the “precise setup”…but further along the line we follow you to your conclusion: “not to be concerned with such a setup”. That’s a bit strange in my ears..


By giving such “conclusions” is exactly the point where things go in the mist.

We have SP22 now saying “oke, so its oke to go ahead with the radials 3..4 feet above the antenna?” What he should do is loose the radials and place the vertical directly above the yagi so that the yagi performance as a the radial system..he would have been better of. Don’t forget you are a forum member with respect, people lissen to you..


I don’t believe you when you say: This is the best you can tell, you know better.


Did you realize the higher lobs only produce a high noise level. That’s nice isn’t it…a a-99 on top of a beam with s9 qrm…we are not waiting for that


I can promise you: if you put up a antenna with ¼ wave radials above a beam it is going to be a problem, a drop of a couple dBs in forward gain and a drop of impedance are easily seen. And im not talking “worst case” secenario here. Ofcourse shorter radials might be no problem, each situation should be verified. There are situations where you just cant “match” the beam anymore.


Your thoughts on the antron moving it forward or backward on the boom is a dead end. The vertical will have a 90 degree shift in its electro/magnetic field compared to the horizontal hence the vertical/horizontal polarization. Further more the antenna is situated on the current bow of the radials, we can attach almost anything there…take for example the boom of a antenna, have you ever considered that strange piece of metal between the elements (boom) ..and how it is possible that it has or does not have influence..


If one insisted on using a antron with radials above a beam (couldn’t tell you why though)..then it might be something to look into it. Though I wouldn’t as it will also bring along mechanical problems. So perhaps we have a briljant solution wich can not be made in the real world.


Conclusion:

A beam with the elements grounded to the boom will provide a good groundplane system. Infact it can be better than most commercial vertical antennas with a radial system underneath it. It is in such a case a good option to drop the original radials.

A vertical with the original radials attached can (doesnt need to) provide serious problems when placed above a beam.


Kind regards,


Henry  19SD348

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