In Southwestern Georgia the conductivity at our tower site is quite poor. It is further made worse by being at the top of a hill. Now, this would be great if we were an FM station having height, but being an AM station which makes no sense to me whatsoever I am looking for a solution to increase the conductivity at our tower site. This might do nothing for us or it could help us. It is my understanding that being at the lowest wettest point for a tower is the best place to be. So, would digging out around the stick and making it an island and having a lake around the tower help with conductivity and push our signal farther, or does some one have any other ideas here???
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Increasing Ground Conductivity
- Thread starter WJEPPD
- Start date
rcombs said:
Not directly around it, it would not effect the radials, i mean aways away from it. I am not saying it is something I would want to do either, I was just asking to see if my theory was barking up the right tree. Don't take ideas and bend them into rulemaking changes, all I was asking is if the theory is right. If it is then it makes an arguement for something else we want to achieve and just want to get feedback from other engineering stand points here...
Also in further reading I have seen people increasing the conductivity of a stations tower by increasing certain metals in the area and not touching the radials. Any input would be helpful. With an increase in ground conductivity would that also decrease ones vulnerability to lightning strikes?
Well, I am not a licensed Professional Engineer, but I did drive by the new Holiday Inn Express they are constructing in my village.
I have followed the articles and anecdotes written on this subject for years. I am led to believe that is would take some very, very sophisticated instruments to measure the before and after results of ALL the changes you mentioned, and I suspect the differences would be very modest.
The same amount of money spent on programming enhancements might improve revenue much more than a very slim change in RF coverage.
I have visited the facilities of a boat-load of radio stations. For small town, rural radio, money spent in locating your operations building on a significantly traveled (by the LOCALS) street or road and then investing in significant flowers around the entrance may get you more revenue for the dollar spent than doctoring up the tower, UNLESS your tower and ground system are a corroded shambles.
Because natural moist earth is likely to be found in the low sites for towers, I think you will find that merely being on a hill top does not necessarily degrade you signal enough to measure.
Create a lobby that shouts via lighting, drawn or open drapes, signs and other means to the passerby: "If you want to come in and drop some news, inquire about advertising, or just see what we look like, come in now" or "We would be happy to meet you, but come another time."
If you are bound and determined that improving the signal needs to be done, one school of thought handles it this way: Drill a well with STEEL casing, use water from the well to keep the ground radials and soil moist, and have an expert tie your tower lightning protection facilities to the well casing.
In spite of my preference for programming and facility appearance, I will grant you that it would be an effective part of your sales pitch to advertisers that explain what all you have done to improve your ground wave signal. They probably won't read this message, and you can convince them that their ads are now covering more area than ever..... whether they are or not.
I have followed the articles and anecdotes written on this subject for years. I am led to believe that is would take some very, very sophisticated instruments to measure the before and after results of ALL the changes you mentioned, and I suspect the differences would be very modest.
The same amount of money spent on programming enhancements might improve revenue much more than a very slim change in RF coverage.
I have visited the facilities of a boat-load of radio stations. For small town, rural radio, money spent in locating your operations building on a significantly traveled (by the LOCALS) street or road and then investing in significant flowers around the entrance may get you more revenue for the dollar spent than doctoring up the tower, UNLESS your tower and ground system are a corroded shambles.
Because natural moist earth is likely to be found in the low sites for towers, I think you will find that merely being on a hill top does not necessarily degrade you signal enough to measure.
Create a lobby that shouts via lighting, drawn or open drapes, signs and other means to the passerby: "If you want to come in and drop some news, inquire about advertising, or just see what we look like, come in now" or "We would be happy to meet you, but come another time."
If you are bound and determined that improving the signal needs to be done, one school of thought handles it this way: Drill a well with STEEL casing, use water from the well to keep the ground radials and soil moist, and have an expert tie your tower lightning protection facilities to the well casing.
In spite of my preference for programming and facility appearance, I will grant you that it would be an effective part of your sales pitch to advertisers that explain what all you have done to improve your ground wave signal. They probably won't read this message, and you can convince them that their ads are now covering more area than ever..... whether they are or not.
WJEPPD said:
That being the case, then let me state what is already obvious to you. I say only to help you stay on track as you work through the logic:
Before you can decide to abandon your hilltop, you must determine is more suitable land is available at an affordable cost. (Owners of desireable land have Sugar Plum Fairy dreams of riches.)
Will local government zoning allow you to use what looks like your dream come true.
BIG QUESTION to pay some money to get the answer: If you move down the road a mile or two because you have found some creek-side muck to plant your tower in, the FCC will require that your relocated transmitter and tower MEET TODAY'S ENGINEERING standards. Your consulting engineer may tell you that you have to reduce your transmitter power 20 to 30 per cent to meet changed station to station interference rules. So you spend all that money and end up with a smaller coverage footprint. I have seen that happen to stations who got an offer from a developer to buy the existing site to build a new subdivision or shopping center.
If it turns out the "cost" (money and/or coverage reduction) is too high, then by all means clean up the present site and spend some money of some of the enhancement chemicals, etc.
Goat Rodeo Cowboy said:
There is one advantage to the present position of the transmitter and that is the rules change that allows a daytimer to run an FM translator 24 hours a day without signing off the AM as long as the AM runs at below 250 watts. Forms still need to be filled out as I know as my attorneys have said this is quite easy now and with the height we have a 250 Watt FM Translator will have some pretty damn good coverage since our height above average terrain is better than anywhere else around and everything goes down hill from here all the way to the gulf of Mexico which pulls our AM signal and helps an FM depending on conditions
WJEPPD said:
Unless the FCC has released something this morning, there has been no such rules change.
You can in all liklihood get an FM translator by having the appropriate forms filled out. It will be under Special Temporary Authority, as the regular rules still don't allow for a translator to carry an AM station. You will have to buy an existing translator, as there is no filing window open right now for applying for new ones. (they're still working their way through the last window. The upside to that is that speculators took out a LOT of translator permits in that window, so there are quite a few on the market...)
Eligibility for STA is not limited to daytimers or stations of less than 250 watts. (I know of at least two Class C stations - 1kw full-time non-directional - that have FM translator STAs. As does at least one 10kw daytimer.)
The FCC does have a proceeding open which would allow routine authorization (without STAs) for FM translators to carry AM stations. Again, unless they did something this morning that proceeding is not complete.
K
kenglish
Guest
Your best bet might be to have a licensed (broadcast) consulting engineer come out and do some measurements on your signal, and thoroughly check out your ground system. You might not have much of an RF ground any more (remember, on most AM sticks, the second half of the dipole antenna is the ground and it's copper radials).
Barring a complete move, you could try a much taller tower, fed at the center, if the conductivity is the major issue. That's the kinda thing a PE gets paid to figure out!
Barring a complete move, you could try a much taller tower, fed at the center, if the conductivity is the major issue. That's the kinda thing a PE gets paid to figure out!
kenglish said:
No one will ever mistake me for a professional engineer, but antennas are a particular interest to me. It would seem to this reasonably well informed layman that ground conductivity pretty much is what it is. That being said, I have been following this thread with interest in hopes I may learn something. The idea of a taller, center-fed antenna tower is one which did not occur to me. Something to consider .... Thanks.
The next question would be quite simple I guess. We get alot of rain here, tons more than other areas. Alot of people have ponds around here,and there is even one along the drive into the station from the main road. Since water is conductive, and especially saltwater, what about a series of ponds around the tower outside the radials to catch rainwater filled with salt that once it rains and they fill up there are instant saltwater conductors. These ponds would fill up and dry out but during heavy wet periods, when a better signal is needed especially to get weather alerts out the conductivity in theory would increase. This would be without changing anything on the tower structure and simply change a grounds conductivity in a non mechanical manor...Thoughts???
Altering the topography will certainly havesome effect on your pattern, but as kyscott suggests, a professional engineer is best qualified to answer the sorts of questions you have.
You seem to be focused on altering the ground conductivity of your area, but this seems to me to be impossible from a geological point of view. It is true that anything one does may alter the radiation pattern, and that this may be important in situations where the station's license requires that its pattern be limited in a certain direction. Anything -- from erecting a chain-link fence to erecting a high-rise building -- within a station's groundwave pattern has some effect on the pattern. A qualified engineer will be able to predict with some accuracy the nature of this effect.
No doubt someone will quickly refute any erroneous things I say here, but it seems to me that constructing a series of salt-water ponds to improve your signal would be more trouble and expense than it would be worth. Just the environmental impact work required would in itself make such a project economically unfeasible, I should think. Frankly, I doubt the benefit derived from such a plan would be negligible at best. I think the money spent on this would be better used to acquire the most up-to-date and reliable broadcast equipment practicable, and to secure the best programming material available to you.
May I make a gentle suggestion? Get yourself a copy of Shrader's Electronic Communication (McGraw-Hill) or a similar text and bone up on the basics of radio engineering. No matter how good an idea may sound, it is really not very good if it just won't work.
You seem to be focused on altering the ground conductivity of your area, but this seems to me to be impossible from a geological point of view. It is true that anything one does may alter the radiation pattern, and that this may be important in situations where the station's license requires that its pattern be limited in a certain direction. Anything -- from erecting a chain-link fence to erecting a high-rise building -- within a station's groundwave pattern has some effect on the pattern. A qualified engineer will be able to predict with some accuracy the nature of this effect.
No doubt someone will quickly refute any erroneous things I say here, but it seems to me that constructing a series of salt-water ponds to improve your signal would be more trouble and expense than it would be worth. Just the environmental impact work required would in itself make such a project economically unfeasible, I should think. Frankly, I doubt the benefit derived from such a plan would be negligible at best. I think the money spent on this would be better used to acquire the most up-to-date and reliable broadcast equipment practicable, and to secure the best programming material available to you.
May I make a gentle suggestion? Get yourself a copy of Shrader's Electronic Communication (McGraw-Hill) or a similar text and bone up on the basics of radio engineering. No matter how good an idea may sound, it is really not very good if it just won't work.
A major point you are missing is that "ground conductivity" goes way beyond the tip of any radial in your antenna system. True "ground conductivity" (or lack thereof
is the ability of a path to propagate a signal between point a and point b. You can modify the ground system all you want (within reason) and still have a crappy signal on the other end. Some parts of the country are blessed with good conductivity, others are not. Pond building will do little, unless you create a pond that is continuous between your tower and the listener....whereever that listener is.
Things like crappy soil, temperature, buildings, trees etc all contribute to a signal degradation of a typical Medium Wave signal.
Not much you can do about that.
is the ability of a path to propagate a signal between point a and point b. You can modify the ground system all you want (within reason) and still have a crappy signal on the other end. Some parts of the country are blessed with good conductivity, others are not. Pond building will do little, unless you create a pond that is continuous between your tower and the listener....whereever that listener is.Things like crappy soil, temperature, buildings, trees etc all contribute to a signal degradation of a typical Medium Wave signal.
Not much you can do about that.
Witchlover said:
A couple of self corrections: It was kenglish who recommended the services of a professional engineer ....
The sentence, "Frankly, I doubt the benefit derived from such a plan would be negligible at best." was intended to read: "Frankly, I doubt the benefit derived from such a plan would only be negligible at best."
My proofreader was in a hurry to have his lunch! ;D
HGR1290 said:A major point you are missing is that "ground conductivity" goes way beyond the tip of any radial in your antenna system. True "ground conductivity" (or lack thereof
Things like crappy soil, temperature, buildings, trees etc all contribute to a signal degradation of a typical Medium Wave signal.
Not much you can do about that.
I think Woody is in the throes of an honest lack of comprehension of exactly what ground conductivity is and what effect it has on a signal. As I said yesterday, a little bone-up on the basics will serve him well. Come to think of it, I could probably benefit from some of the same myself!
HGR1290 said:
Go to the beach south of Tallahassee and some Tampa stations come in like locals. Go 2 miles inland toward Tallahassee and you lose them. Salt water signal is great over salt water, but that's it.
There was a station years ago (I wish I could remember which one! (I THINK it was in Arkansas, but not sure.)) that had a great signal for its power. They moved their tower and lost half their signal reach at the same power.
Why?
The original tower (AND ground system) had been located in a railroad yard!
K
kyscott
Guest
Witchlover said:
Ah, OK. I was beginning to wonder if I was sleep walking, or posting, again!
kyscott said:
No, I was the one posting in his sleep. :-[
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