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Know where to find an affordable Directional Antenna?
- Thread starter bigdummy
- Start date
bigdummy said:
If this is an FM broadcast station upgrade to be authorized and licensed by the FCC, then the specification of its radiation pattern will need to be developed by a consultant. Once that data is available it can be submitted to antenna manufacturers such as ERI, Jampro or Shively with a request to quote an antenna that meets the requirements for the az/el radiation patterns, the antenna mounting environment, and the input power rating needed.
RF
Jampro for lower power, Shively for higher power (the Jampro designs more practical for lower power, especially in the north.
Even for a Class A (around 5 kw or less in radiated power) expect to pay near 20K. The expense is in the special design of the antenna and the testing of the antenna in order to be able to prove to the FCC that the antenna creates the pattern described on the construction permit application.
A thought: If this is a very low power non-commercial (under a 1000 watts) you may want to look at SWR in Ebensburg, PA. They've built special order, highly directional antennas for TV, translator applications and may be able to handle your project.
You will also have to hire a surveyor to stake out/mark your site to insure that the antenna is installed correctly (points the right way!).
Even for a Class A (around 5 kw or less in radiated power) expect to pay near 20K. The expense is in the special design of the antenna and the testing of the antenna in order to be able to prove to the FCC that the antenna creates the pattern described on the construction permit application.
A thought: If this is a very low power non-commercial (under a 1000 watts) you may want to look at SWR in Ebensburg, PA. They've built special order, highly directional antennas for TV, translator applications and may be able to handle your project.
You will also have to hire a surveyor to stake out/mark your site to insure that the antenna is installed correctly (points the right way!).
bigdummy said:
Give David White at ERI a ring. Send him the radiation pattern. They can build and install the antenna. I have had them build and install three directional antennas over the past 5 years. You won't be disappointed.
I have used NiCom's omni stuff on a low power station. They were a good price point for the performance and good service, Never used there directional stuff tho.
http://nicomusa.com/antenna.html
http://nicomusa.com/antenna.html
Unless the CP application specified this particular directional antenna and pattern, this won't work.
Usually the pattern is designed to maximize coverage vs. the protection requirements of the channel. Then the antenna is specially built to produce that pattern.
That's why you are not going to find a cheap directional antenna.
Usually the pattern is designed to maximize coverage vs. the protection requirements of the channel. Then the antenna is specially built to produce that pattern.
That's why you are not going to find a cheap directional antenna.
Nicom and Bext make DA systems but for translators only. You can use a DA based on theoretical patterns on a translator. Can't use these on a full power without pattern study.
I'm not sure that there should be a difference. Any time there has been a full power DA the company charges $5k (Five large) for the pattern you specify they meet. Now they also charge this price if they have made the same antenna a hundred times. Then add another $5k or more for parasitics which are resonant sections of metal added to a bay.
This takes an omni antenna at $6k and runs it to $20k. Most of the time a big DA is only good if your 60 covers parts of a top 50 market. Otherwise going from a Class A to B DA can add just a few listeners.
A client has a class A 6k but a CP for 30kw DA. They are looking at 3 phase power, alternatively a big bay antenna or lower number of bays with more transmitter power, a bigger transmitter, a bigger power bill. By going omni at a B1 power level they can sue their current equipment.
In the 70 it doesn't change the pop more than 1,000 people. In the 60 it is 1500 people. In the 54 dbu it is 3000 people. The pop now in the 60 is 13000 people.
I'm not sure that there should be a difference. Any time there has been a full power DA the company charges $5k (Five large) for the pattern you specify they meet. Now they also charge this price if they have made the same antenna a hundred times. Then add another $5k or more for parasitics which are resonant sections of metal added to a bay.
This takes an omni antenna at $6k and runs it to $20k. Most of the time a big DA is only good if your 60 covers parts of a top 50 market. Otherwise going from a Class A to B DA can add just a few listeners.
A client has a class A 6k but a CP for 30kw DA. They are looking at 3 phase power, alternatively a big bay antenna or lower number of bays with more transmitter power, a bigger transmitter, a bigger power bill. By going omni at a B1 power level they can sue their current equipment.
In the 70 it doesn't change the pop more than 1,000 people. In the 60 it is 1500 people. In the 54 dbu it is 3000 people. The pop now in the 60 is 13000 people.
Unlike AM, an FM DA is not used for the purpose of ADDING population. The DA is used when necessitated by short-spacing situations. And an FM DA is not cookie-cutter. You won't find one that has been used "hundreds of times". The antenna itself is standard, but the parasitic radiators are different for every one of them, and unlike omni FMs, must be tested as a system, including the characteristics of the tower it is mounted on.
ChiefEngineer said:
Really? What attorney are they using, I got some equipment I'd like to sue. ;D
The real world in FM DA is unchanging. Tell an owner he can upgrade from 3 kw to 25kw and regardless of how you explain an FM DA it is the same AM DA issues from years back.
25 kw from 3 kw? My coverage will be a bigger circle. It almost doesn't matter how savy the operator is there seems to be an entitlement issue when you tell an operator the signal upgrade status to 25 kw.
IF you explain the DA issue and leave the power out they seem to want to drop the issue if the pop count is insignificant. Cost of an upgrade is more than the original build out. 3 to 4k people will not pay for this upgrade. Sometimes bragging rights of a Class B is enough for some but this is not justified in population. (Covering 6 counties, 12,000 people, and 36,000 cows....)
I haven't seen a DA placed because the tower site required shortspacing. There is always usually a site that can allow a circle with no DA. These days Horizon and their controlling interest Horizon of California and Calvary Chapel apply at sites that a DA gets more underserved popcounts to beat competing licenses. The odd angels and barely makeable patterns end up though being used over and over.
If you look at the licensed DA fm stations the manufacturers are balking at doing odd patterns. If I reference "station B" thye say "Oh we do that pattern all the time." They are willing to do the other patterns but increasingly $5k for a study seems to favor former already accepted patterns. These are cookie cutter patterns. Yes you will get a pattern study but this is one already done for twenty other stations or more. I have installed at least 70 DA systems over the years. I watch the matter closely.
I am seeing scala antennas with different tower mounting arrangements showing up on multiple stations without new studies. How is it possible a 12 foot face tower on the back side of a pattern has the same radiation pattern as an 18 inch face tower or pole? Clearly it isn't. And this is a scala yagi system with no parasitics. a pole and a 12 foot face tower create the same pattern? No. They are being licensed though.
I am slso seeing some pattern studies with full 50 page reports and others (scala) with a two page report. And in this case we are speaking of Class A FM, not translators.
On translators anyone can offer a pattern and it is routinely accepted by Staff. I have looked at a DA in Owensboro Ky for a translator that interferes with a Class A FM and can't see how this was accepted by Staff. In looking at the antenna the parasitics were not installed at all? or are not protecting the Class A they were designed to.
I suggest we forward the idea to numbskulls that like AM DA systems...the FM DA systems operate more efficiently when you water them. In this manner we could make money installing hundred foot lengths of water hose and sprinkler systems on thousand foot towers.
25 kw from 3 kw? My coverage will be a bigger circle. It almost doesn't matter how savy the operator is there seems to be an entitlement issue when you tell an operator the signal upgrade status to 25 kw.
IF you explain the DA issue and leave the power out they seem to want to drop the issue if the pop count is insignificant. Cost of an upgrade is more than the original build out. 3 to 4k people will not pay for this upgrade. Sometimes bragging rights of a Class B is enough for some but this is not justified in population. (Covering 6 counties, 12,000 people, and 36,000 cows....)
I haven't seen a DA placed because the tower site required shortspacing. There is always usually a site that can allow a circle with no DA. These days Horizon and their controlling interest Horizon of California and Calvary Chapel apply at sites that a DA gets more underserved popcounts to beat competing licenses. The odd angels and barely makeable patterns end up though being used over and over.
If you look at the licensed DA fm stations the manufacturers are balking at doing odd patterns. If I reference "station B" thye say "Oh we do that pattern all the time." They are willing to do the other patterns but increasingly $5k for a study seems to favor former already accepted patterns. These are cookie cutter patterns. Yes you will get a pattern study but this is one already done for twenty other stations or more. I have installed at least 70 DA systems over the years. I watch the matter closely.
I am seeing scala antennas with different tower mounting arrangements showing up on multiple stations without new studies. How is it possible a 12 foot face tower on the back side of a pattern has the same radiation pattern as an 18 inch face tower or pole? Clearly it isn't. And this is a scala yagi system with no parasitics. a pole and a 12 foot face tower create the same pattern? No. They are being licensed though.
I am slso seeing some pattern studies with full 50 page reports and others (scala) with a two page report. And in this case we are speaking of Class A FM, not translators.
On translators anyone can offer a pattern and it is routinely accepted by Staff. I have looked at a DA in Owensboro Ky for a translator that interferes with a Class A FM and can't see how this was accepted by Staff. In looking at the antenna the parasitics were not installed at all? or are not protecting the Class A they were designed to.
I suggest we forward the idea to numbskulls that like AM DA systems...the FM DA systems operate more efficiently when you water them. In this manner we could make money installing hundred foot lengths of water hose and sprinkler systems on thousand foot towers.
Bengalsfan said:
There is no spell check on posts and as much as I love to make sure my words come out the way I type them. Being legally blind many words that use the same letters thye and they use and sue are the same to me.
Remember though with as many lawyers as we have today you can sue anyone for anything.
ChiefEngineer said:
Regulations require a "fully-spaced reference site" that covers City of License, which may or may not be used as the transmitter site. The actual transmitter site still must cover City of License, but may be short-spaced to a co-channel station, which may require operation with less than maximum power for the class, or a notch towards the co-channel station. In any case the main lobe cannot be extended beyond the omni pattern.
Bill Wolfenbarger said:
This does not apply to non com stations however.
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