Can somebody to build medium wave antenna

[Opcom]

this is probably idiotic, but seeing as a helical wound antenna has been used here and there.. would it make any sense to wind a giant coil that happened to be resonant at the proper freequency?

[Gito]

Patrick

   When you mentioned Helically wound vertical antennas,I remberred  an article written about it in the ARRL antenna handbook(chapter 10) that says ...to achieve resonance in a shortened system .....the antenna can be helically  wound to provide a linear distribution of the required inductance, at the end of this article .it says .....Performance of this antenna is comparable  to that of many full-size quarter wave antenna.The mayor design trade-of is in usable bandwidth (narrow band with).

And it also stated  it can be worked against   an above ground radials.Some operators have good result using  with four helically wound radials which are cut for resonance or slightly lower than the operating frequency

A guideline might be to be maintain an element length of .05 wavelength or more.

It's not a idiotic idea at all ,it' a good Idea ,I've read this article before but theres no Idea using it ,before you mentioned it.

The only problem ,is technical problems,.....how to make/build this antenna technically  .

Thanks

Gito.N

[AMroo]

I would be interested to know what frequency you broadcast on and where you got permission or the idea to use that frequency.

[Gito]

Swan

A little History about BC station in Indonesia.about 40 years ago there are many unlicensed small BC stations (Pirate Radio) here ,make the story short the Government then  make rules  " Peraturan Pemerintah Republik  Indonesia  nomor 55 tahun 1970  Tentang Radio Siaran Non Pemerintah (RSNP }( sorry ,in indonesian language)" Rules for non government Radio and we have an organization called PRSSNI,So to have permission to Transmit we must asked/permission to " menteri perhubungan" at that time(in Englih?) and must filled /gived them the documents and so...and so... to get A license for  BC radio.The  permission to used the Frequency is given by Government / Telecommunication minister ,We have 9 Khz channel here

One of the transmitters frequency is 1170 Khz with 600 watt RF output used in Jayapura  -Papua -Indonesia .

Thanks

Gito.N

Ps.Sorry  my English is not good

[AMroo]

 
Thanks Gito you seem like a good man to me, hope to hear your station on soon.

I guess I will have to go away and eat my hat now........any one got any salt and pepper.

[Gito]

Swan

It's only a small MW BC  local radio,that has a limited range about 30 km to 60 km ,Maybe because the poor efficiency of the Antenna , I'm sure you can't hear my radio.
Sorry I can't translate some of my writing in Indonesian to English.Because my English is not good enough

Thanks Swan


Gito.N

[fierabraccio]

Hallo! I'm an old SWL (but AML too). Searching for other things I dropped into this thread and I thought that a little, practical experience would be useful.
In Italy there has been only one case of broadcasting EH antenna, that of Radio 106 in Casagrande (a small place near Reggio Emilia). They transmit in AM on 1040 kHz and have no space for radials. Their antenna worked very well... for some hours, then simply burnt, because it could not sustain a continuous service as required for broadcasting.
The EH was placed on the top of an iron tower supporting other antennas (FM and GPS). After the third time that it was burn, they adopted another system, always with the aim of avoiding radials. This "thing" is made of a coax cable whose outer shield is connected to tower and the center wire to a tiny steel cable that rises oblique for about 53 metres to a pole on the side of the hill. No radials!
Obviously, calculations were of little aid in their case, and they lengthened and shortened the wire until they found the optimal ROS. This system has been in use two years and is still in use without inconveniences, and with a power of 300 W they reach a range of about 100 Km. I don't know if in the world one could find a smaller system for AM broadcasting!
Best regards to all and sincere wishes for Gito (and forgive my bad English, please!).

[Gito]

Hallo Fierabraccio,thank you for writing to me,may I asked you,Does the EH antenna work well before it burnt,what material did They used for the Antenna tubing.(Radio 106 at Casagrande)
I read an article /document(AM_Salvador) about a Medium wave Bc station.Radio Mi Gente.Am 700 in El Salvador that used an EH antenna,looking at the comparison data of 10 Bc station that has been normalized for power and Frequency that the EH antenna will be always will be the best performer for radiation and bandwidth (according this document).


You told me that the Co-Ax shield was connected at the tower,may I ask at the bottom,or somewhere at the tower ,and the tiny steel cable with was connected  to the center of the Co-ax rise oblique from...? is the Co-Ax at the bottom of the tower?(sorry  for my English)
 
Thank You Fierabraccio,best regards too


               Gito.N

[fierabraccio]

Hi Gito! I didn't see the new antenna of Radio 106, I can tell you only that they told me. The hot end of the wire is placed higher than the top of the tower (about 25 metres high), but I don’t know how much higher. The cable shield is connected to tower at its top; but obviously the transmitter itself is connected to earth and in a certain sense the cable shield is connected (through earth) to the base of the tower. This is to say that nobody can know, in absence of further measurements, if only the wire radiates or if everything (wire, cable and tower) is actually radiating because of common-mode currents.
About EH antennas I cannot be of great aid. The principle itself of this antenna has been fiercely questioned. Here some of the major critical reviews:
http://www.w8ji.com/e-h_antenna.htm
http://www.antennex.com/shack/Apr03/ontheeh.pdf.
http://www.antennex.com/preview/archive8/Nov205/intro1105.html
But criticism itself is questionable too. Many of their arguments depend by computer simulations, and computer programmes are based on a common state of knowledge that not considers recent developments as Vladimir Korobejnikov’s theories, on which Ted Hart declares to be based his antenna. Furthermore, some practical measurements were made, but on models (bi-cone or even half-cone) that were abandoned since the times of first CFA antennas.
(But CFA antennas seem to work, because the one you have seen and photographed in Sulawesi is undoubtedly a CFA antenna...).
Neither user’s opinions that one can read on the Web are of great aid. Somebody who tried EH antennas calls them “junk”, “snake oil” and worse; others declare themselves at the top of enthusiasm. But they all are amateurs, and there is a great difference between what an OM requires from his antenna and what is forced to require a broadcaster.
I don’t know why the EH antenna of Radio 106 did not sustain a continuous use. The firm that built it, Arno Elettronica, makes EH antennas for amateurs, perhaps they had not used materials suitable for an heavy-duty employment. But I suppose that they could have done some errors in calculating the feeding network: an antenna does not burn if it radiates correctly, when the RF current produces too much heat there is something wrong in its design.
If you are seriously interested, i may suggest to make some experiment by yourself. If you know somebody who has a FM station (and who obviously agrees to experiment), you can build and try “on the spot” a small antenna, and then decide if it is suitable for you or not. Here are two sites that can be of aid:
http://www.iw5edi.com/ham-radio/?eh-antenna-calculator,43
http://www.darc.de/f39/bastel/2003/wb5cxc/Tuning%20your%20EH%20Antenna.htm
http://www.yu1qrp.4sql.net/projects/files/EHArticles/EH_ANTENNA_DEFINITION.pdf
And that’s all. 73+88!
 

[fierabraccio]

PS - I forgot another useful link, that of the site of Lloyd Butler (a renowned Australian OM who made some interesting developments on EH antennas):
http://users.tpg.com.au/users/ldbutler/index.htm

[flintstone mop]

Gito
I was wondering if your organization would consider using FM instead of A.M.?
A 100 watts can go a long way and a better antenna to manage.
I'm assuming that the radios a lot of folks have today would be AM/FM capable.
Does your ministry provide the radios for the listeners? Or are they thinking that most people have A.M. only radios?
Shortwave would not be good for local coverage.
What type of coverage are you trying to get with the A.M. frequencies?
Fred

[Gito]

Hallo Fierabraccio,Maybe the Radio 106 used the tower as part of the ground system (RF ground) like a modified inverted V Dipole Antenna?with one half of the Dipole (tower) grounded at the end.(bottom of the tower).Actually there are many small Medium Wave Broadcast Station here,that's has lacked of land here,and they used Antennas like me (a short monopole/vertical /about 40 meter and don't use radials,only earth grounds).
Actually if the EH performed like They claim .it will be very useful here  ,in my home town there are  about six to eight Small Commercial M.W B.C station( with small budget/money and land).
Actually I also help to maintain A F.M radio here (as Technician) using 4 CX 5000.A factory build transmitter made in Itally.Yes it used a self supporting tower to place the F.M antenna),but to Experiment you must get permission of the government .
But thanks for your advices,it will help me.


Fred.there's a reason why we choose using Medium Wave AM transmitter.Fred I also help to maintain a F.M transmitter with 3500 watt 0utput and a M.W BC station with 600 watt output
The topography  here consist of hills/mountain and, valeys.
my town is surrounded by mountains ,to my experience ,using F.M there are many blank spot (because the Topography?,natural behavior /line of sight of FM transmission.) using Am (medium wave) we got more uniform transmission(coverage)
Also thinking why the Government still used MW transmitter ,there must be a reason.

Yes Fred before we build these station ,we has a research made,Especially the Topography of the site .
Yes The people there have radios for AM/FM.
We don't use shortwave transmitter.
The aim is to get many listener ,and of course as far as it can to reach the local listener (coverage),with it"s ground wave.


Thank you Fierabraccio and Fred


        Gito.N

[fierabraccio]

Hi Gito! As I read, old AM can be still good....
About your antenna: if your problem is space, EH antennas are not the only way to resolve it. On the 136 kHz band, recently allowed to amateurs, many of them have been forced to contrive solutions to problems of electrically short antennas and lack of space for radials, and I believe that some of their solutions could be usefully scaled down to higher frequencies.
An example could be the ON7YD's capacitive antenna, of which I'm trying to attach an image (if I should not be able, follow the link below):
http://www.strobbe.eu/on7yd/136ant/
There you'll find technical details too.
Best regards & wishes!

[Gito]

Thank You Fierabraccio,it's a great input for me ,I will find this web.


Best regards and wishes too.


Thanks

Gito.N

[DMOD]

Hi Gito,

Here are some folded unipole info that may be helpful:

http://www.nottltd.com/TheUsefulFoldedUnipole.pdf

http://www.nottltd.com/TheFoldedUnipole.pdf

http://www.kintronic.com/Systems/UnipoleSkirtKitGroundedTower.aspx

http://www.nottltd.com/ElevatedRadialSystem.pdf

http://www.lbagroup.com/technology/app10.php

If at all possible, try to obtain the book by Jeremy Raines who wrote a textbook on the topic.

As Don and others have pointed out, try to get as many radials as possible from the base at whatever length you can, and even elevate them if possible.

[Gito]

HI DMOD,Yes the articles you give will be abig help to me,Mike and Jim have told me about this Folded Unipole Antennas,but I can't find much articles about it,Thanks to You for these articles which I've been looking for.




Best Regarts

Gito.N

[fierabraccio]

Vertical folded unipoles require a ground plane as conventional quarter-wave antennas. If I correctly understand Gito’s problem, it is of having not enough space for radials, whose effectiveness depends with their length as (or more than) their number. If Gito could have at his disposal enough terrain, this thread would have no sense.
Rebus sic stantibus, there are only two theoretical solutions:
a)   an earth-independent device, as a vertical dipole, that at AM broadcasting wavelengths poses a lot of problems;
b)   an artificial ground plane of reduced size but with the same effectiveness than an arrange of longer radials, but how one can realize it?
Both theoretical solutions could become practical with fractal antennas. As now, they are used mostly for UHF, EHF and so on (cellular telephony, GPS etcetera), but nothing forbids to use them for lower frequencies. I’m attaching some patterns of most common fractal designs, but there are many other possibilities.
Fractal design have been implemented not only for miniaturizing antennas, but also for miniaturizing ground planes. An arrangement of fractal trees all around a vertical radiator can take a small space and be effective as many longer radials.
 A friend of mine has recently made a receiving fractal antenna as a simple printed circuit on a vetronite board. For a transmitting antenna there would be some other problems, but I don’t believe they would be unresolvable. Here is a link to a site from which one can download many computer programmes for calculating any kind of antenna, fractal ones included:
http://www.si-list.net/swindex.html
And that’s  all as far as I know!

[DMOD]

Valentin Trainotti from Argentina has written some papers in the IEEE Transactions on Broadcasting (March and September of 1999) on the grounded dipole which seem to indicate that ground radials don't seem to matter much for this configuration.

A grounded halfwave antenna (lattice tower) is skirted with four to six wires. The outside of the coax is grounded to the tower near the feedpoint. At about a little over
0.25 Lamba, the skirt begins and at a little lower than that, a point is found for a match of 50 ohms. The center conductor of the coax is distributed out to the skirt. A platform is formed at this height inside the tower for supporting the coax and the skirt feed. No tuner is needed. In essence, the skirt is the matching transformer.

If the tower legs are grounded to some good ground rods, no further lightning protection is need.

I suspect the "Tunipole" mentioned in one of the references I gave you is a version of the Trainotti antenna.

I have the September IEEE paper if you need more detailed info.

Another consideration is to get a series-fed vertical as close to the population center as possible, with as tall a structure as possible (with capacitive or top loading if necessary) with as many radials as you can muster, and feed it with as much power as is legally or technically feasible.

Phil - AC0OB

[Gito]

Yes Phil,what Fierabraccio wrote about the antennas that I need was true a.   an earth-independent device.........b.   an artificial  ground plane.

But of course ,the more knowledge I got concerning many system to use  Vertical antennas ,would help me make more understanding  the + and -  of these antennas.

Phill,I'll be happy If You can give more detailed info about The Trainotti antenna.


Thanks Fierabraccio and Phill

Gito.N

[DMOD]

Gito,

Please see your Private Message.

Phil - AC0OB

[Gito]

Thanks Phil.it must be useful to me.


Gito.N