Not exactly as described in the quote above, but below is a link comparing the real-world groundwave fields measured by a consulting engineer using a calibrated field intensity meter (bottom of that
The link in the opening post of this thread shows an interesting, animated analysis of the elevation gains of a monopole, based on a NEC far-field analysis not including the surface wave. I then post
Dan's AutoEZ charts remove all doubt about the issue of whether or not the ground wave contributes to monopole radiation reaching the ionosphere. Clearly, it doesn't. R. Fry _________________ Topband
Based on the AutoEZ charts linked here by AC6LA, the existence of this "notch" is true only if NEC is misused and/or misunderstood. _________________ Topband Reflector Archives - http://www.contestin
Joe N3HEE wrote: I moved my 160 inverted L to a tall tree in my backyard to get more vertical height. The vertical leg is now about 65 feet and the rest (65feet) is horizontal. .... Any feedback woul
Yuri, Here is a link to a graphic showing a 3D view of the wire model, and the envelope of the total radiated fields. http://s20.postimg.org/6g3f49oml/L_with_Offset_Gnd.png R. Fry _________________ T
We can have 67% reflected power and still have nearly 100% of transmitter power getting into the antenna and being radiated. Then could someone please explain why the manufacturers of ham, broadcast
Hello Paul, RE: Typically a transmitter will fold-back delivered power when its output Z is fixed (e.g., 50 or 70-ohm) and SWR exceeds some predetermined amount set by the manufacturer. This is typic
RE: Brian Mattson's post of Friday, 19 Dec 2014 12:23:52 -0500 The velocity of propagation in the MF and HF bands along radial conductors that lie on, or are buried several inches in the earth is inc
Recalling Jim Brown's posting yesterday of Rudy Severn's excellent recent work, the current maximum in a radial occurs at 0.25 wavelength from it's open end & loss will be minimized when that current
From my reading of posts on many "ham" boards, the prevailing thoughts are that the nighttime skywave field intensity received from a vertical monopole is dependent on earth conductivity -- as well a
The link below shows the transmit site used by WFAN (which is diplexed with WCBS into the same vertical monopole). The site is located on a small island in Long Island Sound. The horizontal distance
Lower angle skip, such as WFAN being received in Europe, Africa, Caribbean, etc. would definitely be affected. In the extreme, the shape of the antenna pattern would look more like the one for ground
... So I would expect the skywave plot to be elongated to the east through south at the 0.25 mV/m contour line. It appears that the data was generated using a signal strength prediction program as "5
CORRECTION: See FCC §73.190 at the link below, not FCC §73.189 (sorry). FCC methodology and formulae used to determine the skywave signals of AM broadcast stations: http://www.gpo.gov/fdsys/pkg/CFR-2
In reality, NEC4 can produce quite accurate results when modeling buried radial wires and groundwave propagation losses along a real earth path -- as long as earth conductivity is known for that path
For most of the past century the intractability of the equations was the excuse for just laying down "textbook" overkill radial systems. If you can't solve the "real world problem", then just change
Radials do have standing waves, and so the minimum impedance at the base will appear when the radial is somewhat less than 1/4 wave long. Of interest here is that the benchmark Brown, Lewis and Epste
Their Fig. 7 shows results of simplified (manual) calculations, not measurement results. Quoting from page 771 of the BL&E paper on ground systems: "The current in the buried wires was measured in ea
Additional from the BL&E paper on the subject of standing waves on buried radial wires... Figure 11 linked below is based on the r-f currents measured along the radial lengths shown in Figure 7. http