John
The issue here is not math. It is the interaction of fields and matter. A good text book is Electromagnetic waves and radiating system by Edward C Jordan and Keith G. Balmain. Chapter 9. You can not ignore the close proximity with ground on 160m antennas for both transmit signal and receiving signal. Too close it became more a transmission line, getting high the irradiation increase and the maximum horizontal power radiated or receiving signal intensity are near 1 ½ wave high. The take off angle depends on the ground itself. 73s JC N4IS From: John Kaufmann <john.kaufm...@verizon.net> Sent: Tuesday, November 27, 2018 8:16 AM To: n...@n4is.com; topband@contesting.com Subject: RE: Topband: Vertical antennas aren't always best for DX In considering the *total power* radiated by any antenna, you need to look at the 3-dimensional antenna pattern, not a 2-dimensional slice. The total radiated power is the 3-dimensional integration of the 3-dimensional radiation pattern. It is convenient to do this in spherical coordinates because that is how we visualize 3-dimensional patterns. In spherical coordinates the integration applies the *smallest* weighting at elevation angles around zenith. Even if the dipole is low, the calculation shows that the fraction of power that goes straight up is small compared to the total radiated power. This is easily understood in 3-dimensional spherical coordinates: https://www.khanacademy.org/math/multivariable-calculus/integrating-multivar iable-functions/triple-integrals-a/a/triple-integrals-in-spherical-coordinat es. 73, John W1FV -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of n...@n4is.com <mailto:n...@n4is.com> Sent: Tuesday, November 27, 2018 6:58 AM To: jkaufm...@alum.mit.edu <mailto:jkaufm...@alum.mit.edu> ; topband@contesting.com <mailto:topband@contesting.com> Subject: Re: Topband: Vertical antennas aren't always best for DX Sorry , but all antenna's on 160m are close to the ground and it is the case, you can check by yourself using EZENEC if you don't know how to calculate the fields. There is no misleading here. 73 JC N4IS -----Original Message----- From: Topband <topband-boun...@contesting.com <mailto:topband-boun...@contesting.com> > On Behalf Of John Kaufmann Sent: Monday, November 26, 2018 8:53 PM To: topband@contesting.com <mailto:topband@contesting.com> Subject: Re: Topband: Vertical antennas aren't always best for DX The statement that the half of a horizontal dipole's radiation is vertically polarized is misleading and needs qualification. There is a vertically polarized component off the ends of the dipole but it is only of consequence at takeoff angles approaching 90 degrees, in other words straight overhead. I would argue that these takeoff angles are of little interest for long distance propagation. At takeoff angles lower than 60 degrees or so, the total radiation pattern of a dipole at any reasonable height becomes dominated by the horizontally polarized component that is broadside to the dipole. The lower the angle or the higher the dipole, the more insignificant the vertical component becomes. This is all verifiable in EZNEC. If this were not true, you would not see the well-defined radiation patterns that are produced by HF Yagi's at higher frequencies were the radiation is horizontally polarized for virtually all signals of interest. 73, John W1FV -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of n...@n4is.com <mailto:n...@n4is.com> Sent: Monday, November 26, 2018 11:06 AM To: 'Roger Kennedy'; topband@contesting.com <mailto:topband@contesting.com> Subject: Re: Topband: Vertical antennas aren't always best for DX Roger Every dipole or inverted V irradiate 50% of the power horizontal polarized broadside with the wire and 50% of the power vertical polarized along the wire. After the first refraction it does not matter. This is an electro-magnetic wave law. You can check that on EZENEC, it is not a anecdote. The advantage over vertical 1/4 wave antenna is efficiency. The vertical efficiency depends on the ground plane resistance, it is common to see invert L with only 50 % irradiated power, the other 50% is dissipated on the ground. "In Theory, we know everything, but nothing works" "In Practice, everything works, but we don't know why" We never will fully understand the 160m band. 73's JC N4IS _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector