** What was the station and location? This allows us to view the location ourselves with Goggle Earth and other tools. etc etc etc The data I posted was sent to me as a courtesy by the consulting eng
But that is NOT the radiation pattern existing close to the monopole, regardless of earth conductivity. That pattern has substantial radiation at angles below 15 degrees. Such radiation will be show
The field over real earth that exists within a few kilometers of a monopole is not very much less for an elevation angle of 10 degrees than it is for the peak radiated field from that monopole. This
Steve K0SR wrote: ...As I stand at the base of my mighty Butternut, I look in any direction and see obstructions. Cars, trucks, garages, hills, telephone poles, sheds, trash cans. The very base of my
According to antenna engineering textbooks (Kraus, Balanis. Johnson & Jasik etc), the free space, far-field radiation pattern is not a function of the distance from the radiator, as it is in the near
Guy Olinger wrote: We will run NEC4 near field calculations on a 1/4 wave radiator with 120 buried 0.4 wavelength radials at 1.825 MHz, soil char of (5, .13). Even at 30 (thirty) km the depth of the
Some earlier posts have implied that monopoles installed at sites with poor earth conductivity don't produce much low angle radiation. Probably this is based on an observation of the NEC far-field pa
Cristi YO3FFF wrote: That means, the radiation pattern will be affected too because the electromagnetic wave will be much curved to the ground, so the groundwave intensity will be direct proportional
The link below shows the NEC4.2 fields for a seawater path on 1850 kHz. The calculated field at 1 km in the horizontal plane for 1 kW of applied power is 309 mV/m. The theoretical maximum field for t
from [Tom W8JI]: The issue here is one of measurement distance and the assumed flat earth, and how much the ground wave contributes to low angle radiation. We obviously know radiation at zero degrees
If I just take a simple program like EZNEC, and use a small sense antenna out in the distance, the results follow the trend you posted from the helicopter. ... AFAIK, we do not have measurements of a
This depends totally on the accuracy of the NEC model, and the analysis that the NEC operator asks NEC to perform -- which depends on the background, skill and experience of said operator. A NEC far-
The tall vertical tower was definitely worse compared to shorter verticals, and had almost no short skip signal around Georgia. I had isolation chokes for lights and a base insulator, but that 300+ f
What is your (or anybody's) definition/understanding of the term "takeoff angle?" R. Fry _______________________________________________ Topband reflector - topband@contesting.com
Guy Olinger replied: Wouldn't that have corresponded to the FCC's reduction in "clear-channel" strategies, and more local market driven commercial agendas? Class A (50 kW, non-directional, 24/7) AM b
Lloyd Berg N9LB wrote: There were numerous technical write ups about stations who wanted the maximum theoretical ground wave signal and spent big bucks to put up 5/8 wave verticals. They were always
At least as important as understanding how 1.8 MHz skywaves interact with the ionosphere is understanding the space-wave fields that are actually _launched_ by a monopole at various elevation angles
... how about 1/2 wave monopoles, or monopoles between 90 and 180 degrees? Could they be useful at any distance on 160? All monopoles of all electrical heights of 5/8WL and less _radiate_ (launch) ma
Presumably the above text was meant to read "So far NEC4 has _NOT_ predicted any real measurements, regardless of operator skill." Some may not recall the comparison of groundwave fields calculated b
In my first post of this date I wrote, "Another important observation to be made from that NEC data is that space-wave radiation from elevation angles below ~2 degrees equals the radiation in the gro