probably about as efficient as you can get under part 15.219
The real roadblock is the ridiculous 3 meter length restriction. That is what really needs to be changed.
The lobbying in DC also needs to end and more public involvement will help.
You know as well as I do someone out there.. a nit picker, will tear that concept setup to pieces over the cap hat and globe. There is no rule saying a 3 meter antenna cannot have a capacitor hat or globe, or even a loading coil, none of which radiate at all.
But...because of "political correctness" garbage and this desire to completely change the meaning of words no matter what the facts are, it is easy for the nit picker to have their day in court by simply applying the fill in the blank line to the meanings.
An apple is an orange and a grape is a coconut. 1 and 1 are 5 and A plus B equals Z.
How could it have gotten this bad? Society not doing their part and not paying attention. All the while being de-educated by the education system so that it is easy to change the meanings of words and to heck with facts...the altered meanings have more "tainment" value.
It's going to be awhile before the chains of hold back are cut.
The design is solid and worth the time it would take to build. This late spring I plan to build a new antenna system to replace the aging antenna system in the antenna farm now with a design very similar to yours, with a provision added to make changing out the radiator element as simple as "disconnect, lift, re-insert, re-connect"..done.
Great design Robert!
RFB
there is a discussion about this design going on over at part 15 broadcasters facebook page
When I find a way to have an account there that doesn't track my every move on the web and throws me into a CIA database along with the 6 billion others on there, I would sign up and check it out!
In-Q-Tel..the CIA's investment arm that funded the start up and continues support of social media outlets such as Facebook.
The way I see it, your design should be implemented regardless of what the nit pickers say. It has been proven, by demonstration and by the numbers, that cap hats and globes and loading coils DO NOT RADIATE. And let's be totally practical here...a cap hat does not add any physical length, nor does a loading coil. A globe may add 1 or two feet of length, but in the real sense of good ol honest engineering, does that 1 or 2 feet beyond 3 meters really going to make that huge of a difference to the 3 meter length to the point it cranks up the efficiency so drastically that it warrants an argument or violation over a mere 1 or 2 feet extra?
No..it won't.
It's all political garbage. Nothing more. Has nothing to do with the technical or the crunched numbers. It has EVERYTHING to do with politics.
RFB
well so far no one has nitpicked the design. i preempted the nitpickers with my arguments.
over on part 15 ers of facebook i had questions which i answered but no one bothered to nit pick it to pieces.
i believe you can read the postings on part15ers without the need for a FB account
I clicked on your link, kc8gpd, and a panel came up requiring that I establish an account.
On radio you cannot see faces.
I spent a few moments studying the antenna diagram, and would describe it as a deluxe 3-meter antenna with a very hardy ground radial system.
The only part that is not obvious to me is the large globe so-called "top hat."
I also think we can save words by compressing the words "capacity-hat" into the simple nickname: "cap-cap."
But about the hat. By simply presenting a drawing of a large cap-cap there is no point being made at all, except that it is round and probably difficult to keep from rolling off the top.
What we need is a technical theory describing what the cap-cap achieves, why the particular size and shape are beneficial, and the results of real-world tests using a test model.
Is that information over on Face Book?
the size and dimension of cap would require experimenting. the more capacitance you can put at the top the less loading is required at bottom and the more equal the rf distribution is along the radiator.
It is the very reason why Isotrons work so incredibly well. A cap at the top, and a cap at the bottom and nothing but a coil in between.
In a sense, the 3 meter stick functions in the same manner with the addition of a cap hat and very good ground radial system, which forms the bottom cap, and the radiator in the middle is the coil like that in an Isotron.
Running the numbers, anyone with elementary level engineering understanding can see the design is not just technically meeting the limits but also meeting the legal aspects of Part 15.
I too get the same message from the link...sing up to view.
RFB
ok i guess than you must be signed up now period regardless of the pages view settings.
I did not think of it that way. my design does resemble a ground level an am broadcast band 3m high ISOTRON (they do make a p15 compliant ver. for x-band)over a ground radial system.
I had a gigantic top hat. It was
five feet in diameter. That's about
half the size of the antenna. The
top hat "phased itself out" - you
know what I mean - it didn't radiate.
I checked it with a field strength
meter.
It required a lot of guy wires.
That was 3 years ago. That installation
has been off for 3 years. So far nobody
has knocked on the door and complained
about it. The 3 meter stick was on the
ground - the transmitter was on the
ground, and there were 16 radials.
I maintain that the top hat is not a radiating
device if it is made correctly. And don't
the ground wires not radiate either, for the
same reason?
For me, it was an experiment, and I think it
was a very good experiment. And besides, my
programming was so boring, that nobody would
have cared anyway.
After all, how many radio stations play
jazz bagpipes all the time?
Hey, if you drive all of your listeners away,
you could probably run higher power. (I say
this in jest of course.)
Bruce, DOGGRADIO STUDIO 2
There are already stations that raise their power and then drive all their listeners away.
They are called licensed stations.
I feel bad. I should have said
something to you KC8GPD, because
it really is a very nice antenna
design. By "nice," I mean - it's
a really really good design.
And for some reason, I really like
the way you drew it, too. It gives
me that real "engineering" feel.
For whatever it's worth and best wishes,
too -
Bruce, DOGGRADIO STUDIO 2
When me and the xyl finally get a house together hopefully I can convince her to allow me to set this antenna system in backyard
Robert, I also hope you get a chance to construct and test your design. It is very interesting.
Now for a bit of nit picking and I invite critique. We all probably agree that a top hat symmetrical in the horizontal direction from a vertical monopole will not radiate. This is because the field produced by current in one direction in the top hat is canceled by that produced by current (equal and opposite) in the 180 degree opposed direction. even in a solid plate. Mathematically this can be determined by integrating the vector component of the current in the given direction along a line from one edge through the center to the other edge which would yield zero.
Applying the same integration technique to the surface of a sphere, for example taking a line integral from the bottom of the sphere along a line on the surface of the sphere to the top using the vertical component of the current vector and adding this to the same integral along a line 180 degrees on the opposite side of the sphere will produce a non-zero total field because the vertical vector current components along each path are in phase assuming the currents are flowing in the same direction such as from bottom to top which would be expected in this case. The only way the fields would cancel with no net radiation from a sphere is if the current on the left half of the sphere flows up while the current on the right half flows down. In other words, the current would have to be symmetrically circulating around the sphere around an axis perpendicular to the monopole and going through the center of the sphere. I can't imagine this happens in a sphere which is small compared to the RF wavelength.
Concerning the referenced experiments I would ask how one separates the field produced by the monopole from that of the sphere during the measurement.
Comments?
Neil
Yes....same analysis I was pondering on the sphere. However that miniscule amount of radiation will be..well miniscule at the wavelength were talking about. Comparing the apples to oranges (stick vs globe), and add the fact there is a cap disc in between, any measured radiation off that globe will be seriously overtaken by radiation coming from the stick.
Now if we were using this setup as a split band antenna system, a very common technique used in HAM radio, not broadcast, we can construct this thing to allow for dual band use, or more, and that again will depend on the wavelengths used and what the antenna was designed for.
The size of the sphere is simply too tiny to make any practical difference in radiation emitted from it, again taking into account where the mean radiation is coming from...the stick.
Now if the entire antenna was nothing but a sphere 3 meters diameter then we have something to discuss. But in this design, the size of the globe and large cap hat in between pretty much puts that sphere and any radiation from it into the irrelevant category...again noting the mean radiation coming from the stick. That radiation field is not going to be uniform from bottom to top past the cap hat and magically continue in the vertical field with the same intensity as is from the stick, nor will it add any relevant radiation intensity to what is being emitted off the vertical stick or take the design concept so outside of it's intent that it warrants any concern. The sphere is simply too small for the wavelength used that it would jack up the field intensity as if stacking another stick past the cap hat.
Maybe put an RF choke between the cap hat and globe will satisfy the nit picks...well it didn't satisfy the big nit pick but who knows..might keep the noise to a dull roar!
RFB