Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
MK,
How satisfying it is to read your message, written in plain, easy to understand, well-punctuated English, without any undeciferable coded abbreviations. I agree with what you say although I am unfamiliar with exactly how the FCC fits into the scheme of things. Amateurs and commercial broadcasters have a common fundamental requirement. There is a service area to be covered with a given field strength. Depending on frequency, requirements then diverge. But the design methods used to satisfy requirements are all confined (or should be) to the principles of engineering economics. Inevitably, the Dollar, Pound, Frank, Mark, Rouble and the Yen rule the roost. Both commercial broadcasters and amateurs do a cost-befit analysis. The broadcaster takes into account the revenue acruing from selling the service. The amateur, whether he likes it or not, has to ask himself what the satisfaction of using the station is worth. Amateurs' bank accounts are not unlimited. Field strength at the limits of the service area depends on the power efficiency of the radiating system. If engineering economics dictate use of a set of buried ground radials then the peformance of the ground radials must be included. Considering the system as a whole, it may be economical NOT to achieve the maximum possible radiating efficiency. Indeed, the maximum is seldom the target. If there is an economical choice in the matter, once the location of the station is decided, everybody agrees that efficiency depends on soil resistivity at the site. To estimate efficiency it is necessary, at the very least, to make a guess at soil resistivity. Perhaps just by looking at the type of weeds growing in it. Or it can be measured. Depending on how far it enters into station economics, it is possible to numerically estimate efficiency from the number and length of radials AND FROM SOIL RESISTIVITY. B.L & E and the FCC don't enter into it. ---- Reg. ======================================== MK wrote, The only stations that the FCC is concerned about is commercial. And the reason they stick with the standard number is for stability and getting the max bang for buck, and an easily expected performance level. Buying a load of wire will beat using more transmitter power over the long run. If they use 120 radials, they know they will be getting close to maximum performance. If they don't, it's a crap shoot. 120 radials *will* outperform 16 of them. There is no question, unless they are over sea water. I'm not saying hams have to run that many. In fact, I think 60 will do for most, except the most hard core for good results. Even less for the more casual user. But I have no problems with the FCC wanting a certain level of performance for commercial stations. I have no problems seeing why they do it either. Wire is cheap compared to todays level of monthly light bill. With some stations, the radials, or lack of , in certain directions gives them a controlable pattern with no surprises in f/s over a period of time with changing ground conditions. The main thing is stability of performance over periods of time. Or thats my take anyway. MK |
#2
![]() |
|||
|
|||
![]()
On Wed, 7 Sep 2005 14:07:39 +0000 (UTC), "Reg Edwards"
wrote: MK, How satisfying it is to read your message, written in plain, easy to understand, well-punctuated English, without any undeciferable coded abbreviations. I agree with what you say although I am unfamiliar with exactly how the FCC fits into the scheme of things. Amateurs and commercial broadcasters have a common fundamental requirement. There is a service area to be covered with a given field strength. Depending on frequency, requirements then diverge. But the design methods used to satisfy requirements are all confined (or should be) to the principles of engineering economics. Inevitably, the Dollar, Pound, Frank, Mark, Rouble and the Yen rule the roost. Both commercial broadcasters and amateurs do a cost-befit analysis. The broadcaster takes into account the revenue acruing from selling the service. The amateur, whether he likes it or not, has to ask himself what the satisfaction of using the station is worth. Amateurs' bank accounts are not unlimited. Field strength at the limits of the service area depends on the power efficiency of the radiating system. If engineering economics dictate use of a set of buried ground radials then the peformance of the ground radials must be included. Considering the system as a whole, it may be economical NOT to achieve the maximum possible radiating efficiency. Indeed, the maximum is seldom the target. If there is an economical choice in the matter, once the location of the station is decided, everybody agrees that efficiency depends on soil resistivity at the site. To estimate efficiency it is necessary, at the very least, to make a guess at soil resistivity. Perhaps just by looking at the type of weeds growing in it. Or it can be measured. Depending on how far it enters into station economics, it is possible to numerically estimate efficiency from the number and length of radials AND FROM SOIL RESISTIVITY. B.L & E and the FCC don't enter into it. ---- Reg. Sorry to disagree, Reg, but it appears you're overlooking an important point--the difference between the efficiency of the radiating system itself, versus the efficiency of the ground area external to the radiating system. BL&E shows that when 90 - 120 (actually 113) radials of 0,4 w/l form the ground system for a 1/4 wl radiator, the efficiency is 98.7% efficient, REGARDLESS OF THE SOIL RESISTIVITY UNDER THE RADIALS. This is shown by obtaining the field strength of 192 mv/meter at 1 mile for 1000 watts delivered to the antenna under the conditions described above, compared to 194.5 mv/meter with a perfect ground having an efficiency of 100% It is only the soil resistivity of the ground external to the radial system that determines the field stength external to the radial system. Consequently, the soil resistivity (or conductivity, if you like) is significant only in the areas external to the radial system. Walt, W2DU |
#3
![]() |
|||
|
|||
![]()
On Wed, 07 Sep 2005 11:41:33 -0400, Walter Maxwell
wrote: Sorry to disagree, Reg, but it appears you're overlooking an important point--the difference between the efficiency of the radiating system itself, versus the efficiency of the ground area external to the radiating system. Walter, my friend, you're beating a dead horse. It would appear that Reg's mind is made up and no amount factual proof is going to change it. Had BL&E been Englishmen I sure things would be different.G 73, Danny, K6MHE |
#4
![]() |
|||
|
|||
![]()
On Wed, 07 Sep 2005 09:39:28 -0700, Dan Richardson wrote:
On Wed, 07 Sep 2005 11:41:33 -0400, Walter Maxwell wrote: Sorry to disagree, Reg, but it appears you're overlooking an important point--the difference between the efficiency of the radiating system itself, versus the efficiency of the ground area external to the radiating system. Walter, my friend, you're beating a dead horse. It would appear that Reg's mind is made up and no amount factual proof is going to change it. Had BL&E been Englishmen I sure things would be different.G 73, Danny, K6MHE Good point, Danny, how true. Walt |
#5
![]() |
|||
|
|||
![]() Dan Richardson wrote - Had BL&E been Englishmen I sure things would be different.G ==================================== They sure would! They would have been instructed to go back and finish the job. ---- Reg. |
#6
![]() |
|||
|
|||
![]()
Dan Richardson wrote -
Had BL&E been Englishmen I sure things would be different.G ==================================== They sure would! They would have been instructed (by their employers) to go back and finish the job. ---- Reg. ===================================== I am reminded of the military engineer who was dispatched by Napolion, an engineer himself, in connection with standardisation of the Metre, to measure the distance between the Earth's Equator and the North Pole. Measurements began, but the further the engineer departed from his beautiful lady friend in Paris the more difficult it became to make progress along the route. Eventually, he couldn't withstand the mental and physical stress. He returned to her Parisian boudoir and resorted to cooking the books in what time he had to spare. So, the International Standard of Length, The Metre, held in Paris, France, carefully guarded by the German occupying forces during WW2, may or may not be equal to 39.37 English inches. Actually, the most fundamental physical measurement standard is the Mass of the Standard Kilogram on which everything else depends. But it is quite an arbitrary quantity. I have just finished a bottle of Blossom Hill, Californian, white wine. Makes a pleasant change to arguing about what 'amateurs' BL&E might, or might not have done before leaving the site. ---- Reg. |
#7
![]() |
|||
|
|||
![]()
Reg Edwards wrote:
Dan Richardson wrote - Had BL&E been Englishmen I sure things would be different.G ==================================== They sure would! They would have been instructed (by their employers) to go back and finish the job. ---- Reg. ===================================== I am reminded of the military engineer who was dispatched by Napolion, an engineer himself, in connection with standardisation of the Metre, to measure the distance between the Earth's Equator and the North Pole. Measurements began, but the further the engineer departed from his beautiful lady friend in Paris the more difficult it became to make progress along the route. Eventually, he couldn't withstand the mental and physical stress. He returned to her Parisian boudoir and resorted to cooking the books in what time he had to spare. So, the International Standard of Length, The Metre, held in Paris, France, carefully guarded by the German occupying forces during WW2, may or may not be equal to 39.37 English inches. Actually, the most fundamental physical measurement standard is the Mass of the Standard Kilogram on which everything else depends. But it is quite an arbitrary quantity. I have just finished a bottle of Blossom Hill, Californian, white wine. Makes a pleasant change to arguing about what 'amateurs' BL&E might, or might not have done before leaving the site. ---- Reg. All the above is/maybe true but remember that all the formule work using the values represented in the METRE and the KILOGRAM. Something must be correct here.... Dave WD9BDZ |
#8
![]() |
|||
|
|||
![]()
David G. Nagel wrote:
SNIPPED for readability All the above is/maybe true but remember that all the formule work using the values represented in the METRE and the KILOGRAM. Something must be correct here.... Dave WD9BDZ Yep! Everything simply requires adjustments to proportionality constants, Reynolds numbers, Plankian constants, etc. |
#9
![]() |
|||
|
|||
![]()
On Thu, 8 Sep 2005 16:09:23 +0000 (UTC), "Reg Edwards"
wrote: I have just finished a bottle of Blossom Hill, Californian, white wine. Makes a pleasant change to arguing about what 'amateurs' BL&E might, or might not have done before leaving the site. ---- Reg. I hate to say this, Reg, but calling BL&E 'amateurs' is insulting to me. I knew them well, and worked with B and E in the RCA Laboratories antenna lab, and they are anything but 'amateurs'. I think you finished off the Blossom Hill to rapidly. Perhaps you should take a look at the long list of IRE articles published by Dr. G.H. Brown, reporting his work that shaped the present design of all AM BC antennas. Did you ever wonder what happened to the diamond-shaped AM towers? And why the AM towers constructed since 1940 have a uniform cross section? And did you know that Dr. Brown gave John Kraus, W8JK, the idea of close spaced elements that culminated in the 'W8JK Beam' antenna? L, (Bob Lewis) is also a fine engineer, although he is also a ham, W2EBS. Walt |
#10
![]() |
|||
|
|||
![]()
| Sorry to disagree, Reg, but it appears you're overlooking an
important | point--the difference between the efficiency of the radiating system | itself, versus the efficiency of the ground area external to the | radiating system. | | BL&E shows that when 90 - 120 (actually 113) radials of 0,4 w/l form | the ground system for a 1/4 wl radiator, the efficiency is 98.7% | efficient, REGARDLESS OF THE SOIL RESISTIVITY UNDER THE RADIALS. This | is shown by obtaining the field strength of 192 mv/meter at 1 mile for | 1000 watts delivered to the antenna under the conditions described | above, compared to 194.5 mv/meter with a perfect ground having an | efficiency of 100% | | It is only the soil resistivity of the ground external to the radial | system that determines the field stength external to the radial | system. Consequently, the soil resistivity (or conductivity, if you | like) is significant only in the areas external to the radial system. | | Walt, W2DU Walt, What if the ground outside the radial system was comprised of 30-1000 feet of sand and rock overlying any conductive soil below? Would we then be able to measure 192 mv/meter at one mile with our 113 radials of 0.4 w/l? Ron, WA4IWN |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Inverted ground plane antenna: compared with normal GP and low dipole. | Antenna | |||
How to measure soil constants at HF | Antenna | |||
Why a Short Lightning Ground? | Antenna | |||
The Apollo Hoax FAQ | General | |||
QST Article: An Easy to Build, Dual-Band Collinear Antenna | Antenna |