Ok Done! We’re Ready!
I finished the Part 15.219(b) Suggestions for Rule Making. To allow for a more efficient antenna system. You can download a copy here:
Ok Done! We’re Ready!
I finished the Part 15.219(b) Suggestions for Rule Making. To allow for a more efficient antenna system. You can download a copy here:
Part 15.219(b) Suggestions for Rule Making PDF
http://lpam.pbwiki.com/f/15.219%20%28b%29%20Rule%20Making%20Petition.pdf
I will continue to review the text for corrections that may have escaped my eyes and only make those changes as needed. So it will remain as it reads now.
Those of you who wish to support the cause of this Rule Making Petition, and sign on with your signatures. Should go to the LPAM group at Yahoo and join with the rest of the various advocacy groups and forums who meet there. Quite a few parties check in there. We need as many interested parties and or advocacy groups as we can have, such as part15.us members also. So weigh in and lets make some new FCC rules.
http://groups.yahoo.com/group/LPAM/
So copy this url down!
And stir up everyone to join in the ranks!
There are a few attorneys there who are LPAM’ers at the group. Part 15 station owners, etc. Who have already filed previous comments and petitions who can pick up this petition and sponsor it with their signatures and cover page. I am sure that as advocates they are not going to charge us Part 15 folk a fee. And so when it comes time, you can add your signature which is merely you name and address added to the text documents. You do not have to physically hand sign anything, just add you text name and address here from online means. But you will have to wait until them fellows read and get stirred and pick things up. You know, being it is the Holidays now. So you can go there and comment and suggest they stir up and sponsor this. They do have the petition there now to look over.
For now you should read the draft and note it’s contents. And ponder what can be done with it. I mean if others wants to pick it up and sponsor it.
I reviewed the definitions and terms so I made sure I did not cross terms. Not confusing one thing with another. It takes awhile to catch on to the FCC terms. So I hope it reads right, like it should. And as I said I will continue to review it for refinements in spellings as I note them.
Near the end of the document is an interesting software designed antenna for you. The base loaded SSTRAN antenna only calculates to be 3% efficient when run through the software. Which is way more efficient than the radiator of 15.219(b) as is in the current rule. And naturally is a better antenna than the rule specifies. (Based upon a ground radial system of 1 ohm.) The antenna herein designed with software is 15.79% efficient. So some of you might find that interesting. 5 times more efficient than the SSTRAN. And I like the SSTRAN concept, I think it is good.
Anyways, looking for supporters and sponsors!
Merry Christmas!
Daniel Jackson
WHHR 1680 kHz
URL of Petition:
http://lpam.pbwiki.com/f/15.219%20%28b%29%20Rule%20Making%20Petition.pdf
Regarding the antenna comment below.
The fellows EZNEC antenna analysis is wrong, look at my version of it:
http://whhr.pbwiki.com/f/3_meter_monopole.gif
radio8z says
Proposed AM rule changes
Daniel,
You obviously have put a lot of thought, time, and work in composing your proposal and you are to be congratulated for your efforts. With this in mind, the following is meant to be constructive and not critical and I trust you will read it as such.
Regarding the SSTRAN type or other coil resonated antennas, the general reading of the rules allows this structure since the coil length is included in the length limit and does not directly contribute to the radiation. A test case may have to be made to affirm this but a strong defense is that the coil does not radiate any more than a comparable length of conductor.
One feature of your proposal which I recommend you reconsider is your listing of specifications rather than standards. For example, it is better to list the suppression of out of band signals than to specify a 5 element filter. Decoupling the transmission line should be left to the designer and not to specific methods such as burial or Faraday cages. By establishing standards you allow the designer greater latitude than if you specify specific methods or hardware.
There is no need to require a SWR meter. If a designer wants to include a “tuning” or “match” indicator, that is fine, but I would not want to see it required.
If the goal is to provide the greatest increase in range for part 15 AM then I think it is simple: Allow longer antenna/transmission line/ground lead lengths than 3 meters. This will have the biggest impact on range and can be applied using existing equipment.
I understand that you are trying to assure the FCC that harmful interference will not happen but the more specific you get in your proposal, the more restrictive any rule changes become.
Thanks again for what you are doing, and thanks for reading my reply.
Neil
Dan Jackson says
Thank You
Thank You
Given some thought on the Faraday Cage I agree with you. I recalled the use of toroid chokes on the coax for suppressing coax outer shield currents. So I should make that comment and leave this all open for using the most current and up to date proven methods. On this application point. And the station can use the best method proven at the time. Or any good method from an earlier time. I should consult my radio handbook on this and see what diagrams and devices they have listed for a choice of uses?
Now this proposal does not effect anyones current use of Part 15. It will not impose limitations on those 15.219(a) stations using the set up in 15.219(b). It only creates a sub class or augmented class of Part 15 authorized to use new antenna systems in a small spectrum. This new class would be limited to that spectrum and those who are using the 15.219(b) as it is now will still be able to use that all over the broadcast band un effected by these suggestions. And that is spelled out. So this will not alter the current Part 15 stations. It only enhances the Part 15 uses.
The low pass filter does specify a cut off of 50 dB at 1780 kHz or below. To not specify a low pass filter of 5 elements will mean that a claim of this attenuation could be made for a 3 element (simple Pi) low pass filter and some will try to sell that. But it will not work that way.
I see too many examples of people selling things that are suppose to be type accepted when they are not.
Dan ka9rza
Rich says
Part 15.219(b) Suggestions for Rule Making PDF
Daniel,
Concerning your/Reg Edwards’ “Software Designed Antenna Analysis” from the comments in your PDF paper, the link below leads to a modern NEC-based analysis of the system you described. The NEC study is based on a ground-mounted, resonant 3-m monopole on 1650 kHz, coil-loaded at about 2/3 height, with a 25 ohm r-f ground and 5 ohms of coil loss. This might be considered a rather “average” set of parameters for this configuration.
There is a considerable difference between the gain of this system as calculated by NEC, and the one you are proposing in your text.
Note that the peak gain calculated by NEC is -15.45 dBi (upper right window), which is about 20 dB worse than the gain of a 1/4-wave monopole using a 1-ohm r-f ground. Reg Edwards’ program calculated only an 8 dB difference compared to the near-perfect 1/4-wave system.
That 12 dB difference between the two analyses is very large: -12 dB converts to a power multiplier of about 0.063.
If you want to make your presentation relate better to real-world values, you might want to re-consider including that result from the use of Reg Edwards’ program.
Here is the link:
http://i62.photobucket.com/albums/h85/rfry-100/3mMonopolecoilat61Hgt.gif
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Dan Jackson says
Thanks on the comment about
Thanks on the comment about the NEC software. If I can down load it I will use it.
I still have some time to re model things and see what happens.
Thank you!
Dan Jackson says
Another comment. I have MINI
Another comment. I have MINI NEC and it will not deal with antennas beneath .2 lambda.
MMANA gets the gain all wrong on short verticals like this.
Let me work on it more.
Dan Jackson says
EZNEC Calculates nearly the same
EZNEC Calculates nearly the same….
3 meter high monopole 1.65 mHz
with 3556.442uH 2/3rds section loading coil
from R.J. Edwards: “VERTILOAD.EXE”
Coil reactance = 36,870.5438 ohms = 36.87K load 1
EZNEC calculated feed point = 1 ohm -j 0.001239 @ 0.07 degrees -6.19 dBi gain from EZNEC -8 dB loss from VERTILOAD.EXE antenna gain = 1.81dB after losse
I did the same antenna as you using EZNEC.
You can see from the graphic file here:
http://whhr.pbwiki.com/f/3_meter_monopole.gif
And you can download the EZNEC files here:
http://whhr.pbwiki.com/f/3_meter_monopole.zip
From MMANA, I calculated the coil load as 3556.442uH
based upon the physical data of VERTILOAD.EXE.
The antenna is 9.8425 feet high.
You had a 25 ohm resistive load in the antenna,
hence two loads. The design only has 1 inductive load.
You inserted a 25 ohm load to invent a ground.
This does not equate to a good ground of 1 ohm standard at the feedpoint as I have in VERTILOAD.EXE
NEC does not calculate performance well of a
vertical antenna less than .2 lambda high. Thats it’s
limitation.
So the compenstion is to use a pastorial grade ground
medium of 0.005 S/m with a dielectric of 13, and a copper wire loss factor to equate to the actual real life antenna. The antenna is calculated against a real ground and not a Perfect ground. So with these losses above, the antenna still works near to the
R.J. Edwards software calculation. About all I see different to any great degree is the calculation of the antenna gain of 1.81dB after losses based on the data of both softwares.
R.J Edwards software VERTILOAD.EXE is comparing
the dB loss factor to the radiated output across the radiation resistance R2 (without antenna field pattern gain applied) versus the feed point input energy. It can not calculate gain due to the field pattern which EZNEC has added 1.81dB to the antenna.
The ground is based upon a 1 ohm ground radial system, where the ground surface is equal to 3,441.6 square meters or 0.003 ohms/m at a dielectric of 13 for this file. Due to the ground radial system.
MINNNEC REAL GROUND of EZNEC @ dielectric
of 13 will do fine and is used here.
Ground data must be input based upon the ground system you have in ohms/m^2 (in meter squared terms). 10 meter radial wire length = 10 meter radius
= 3,441.6 square meters1 ohm standard / 3,441.6 square meters = 0.003 ohms/m squared
The ground radial system then has 10 meter long radials.
Around 60 radials total is the vision here.
Rich says
Not Nearly the Same
Dan Jackson wrote about my EZNEC data (in italics below):
3 meter high monopole 1.65 mHz
with 3556.442uH 2/3rds section loading coil
from R.J. Edwards: “VERTILOAD.EXE”
Coil reactance = 36,870.5438 ohms = 36.87K load 1
EZNEC calculated feed point = 1 ohm -j 0.001239
@ 0.07 degrees -6.19 dBi gain from EZNEC -8 dB
loss from VERTILOAD.EXE antenna gain = 1.81dB
after losses.
Sorry, Dan, but your method of analysis is inappropriate for Part 15 AM systems.
NEC calculates the radiation pattern at an infinite distance, according to whatever ground characteristics are defined in the model.
But the practical service range of Part 15 AM systems does not extend to infinity. Neither does the r-f ground of a practical/typical Part 15 AM system equal 1 ohm — which is lower than many/most licensed AM broadcast stations using 120 buried radials each at least 1/4-wave long.
Note that r-f ground resistance is not a DC resistance of a wire or rod, but the r-f resistance to the currents returning to the antenna+transmitter system as a result of r-f currents induced into the earth up to 1/2-wavelength from the radiating conductor(s).
Other things equal, the field strength of any monopole within the the first kilometer or so of the antenna site is not much lower over paths of average ground conductivities than it is over a perfect ground.
You had a 25 ohm resistive load in the antenna,
hence two loads. The design only has 1 inductive load.
You inserted a 25 ohm load to invent a ground.
This does not equate to a good ground of 1 ohm standard
at the feedpoint as I have in VERTILOAD.EXE
My 25 ohm load was not in the antenna, but between the transmitter chassis ground connection and the r-f ground connection to a perfect ground plane, to account for r-f ground loss. This is the same technique used by the FCC to determine the “efficiency” of monopole radiators used by licensed AM broadcast stations. An r-f ground loss of 25 ohms is ~typical for Part 15 AM setups.
NEC does not calculate performance well of a
vertical antenna less than .2 lambda high. Thats it’s
limitation.
But it does. The difference between your/Reg Edwards’ numbers and mine mainly was due to the 24 ohms of difference between my r-f ground loss, and yours.
My NEC model showed 0.21 ohms Rr for my configuration, which was based on your description. The result of your/Reg Edwards’ calculation was 0.26 ohms, including some ohmic loss for the radiating conductors.
NEC is a powerful tool, but there is a learning curve not only to NEC, but to antenna radiation theory and practice. And as I discovered when I first began using it, GIGO 🙂
//
WEAK-AM says
Near field condition
Rich says: “Other things equal, the field strength of any monopole within the the first kilometer or so of the antenna site is not much lower over paths of average ground conductivities than it is over a perfect ground.”
This is a very interesting remark. I am curious to know if you can substantiate it? Note, I am not disputing it, merely wanting to understand why this would be true.
The reason it is interesting is that, despite claims to the contrary by some, it is my experience that a legal Part 15 AM station generally does not provide useful coverage beyond a km, and in most cases considerably less. This does not mean you could not receive it further away, in the complete absence of interference, with a sensitive receiver, etc. But as a practical matter, any reception beyond this distance is generally for DX’ers only. Thus, if ground conductivity is relatively inconsequential at distances of less than 1 km, it could be concluded that the normal service area of a Part 15 station is relatively independent of ground conductivity. That is an important thing to know.
WEAK-AM
Classical Music and More!
Rich says
Part 15 AM Propagation Loss
RE: Near field condition
WEAK-AM wrote: Rich says: “Other things equal, the field strength of any monopole within the the first kilometer or so of the antenna site is not much lower over paths of average ground conductivities than it is over a perfect ground.”
This is a very interesting remark. I am curious to know if you can substantiate it? Note, I am not disputing it, merely wanting to understand why this would be true.
Sorry for the late response here. I don’t know how I missed reading the above comment from WEAK-AM.
The proof of my statement quoted above lies in the work of George H. Brown, et al, of RCA – Princeton, who in 1936 experimentally determined the groundwave field intensities radiated by monopoles of various heights, with ground systems of varying lengths and numbers of buried radials. The r-f power applied to each configuration tested was constant. The test frequency was 3 MHz.
The experiments were carried out in the sandy soil of New Jersey, where earth conductivity is poor — about 4 mS/m (or less). Their work was the basis for the FCC’s requirements for the minimum antenna system standards for licensed MW broadcast stations in use to the present day.
The link below leads to data from Brown’s study. Figure 30 there shows that the groundwave field intensity at one mile for monopoles from about 50 to 90 degrees in height using 113 radials each 0.421 lambda in length is within a few percent of the theoretical maximum for a perfect monopole over a perfect ground plane. Field intensities were measured 3/10 of a mile from the monopole systems, so it is clear that the propagation loss over about 1,450 feet of sandy soil had little affect on the measured fields.
For very short monopoles the field drops sharply, as even the low resistance of a “broadcast type” radial system is considerably higher than the radiation resistance of a very short monopole, and most of the applied r-f power is dissipated in the r-f resistance of the ground system.
Finally, while 1 km may be considered to be “near” to a Part 15 AM setup, it is well beyond the near-field boundary of a 3-m monopole mounted with its base at earth level that is defined by physics. That distance for such systems operating toward the top of the MW broadcast band is less than 200 feet.
Brown’s data: http://i62.photobucket.com/albums/h85/rfry-100/G.gif
//