Can a mobile antenna question fit into TOWERTALK? Would a top hat attached to a mobile screwdriver antenna be a beneficial addition even if used only when stationary? Just wondering if it would make
be a beneficial wondering if it would make make it possible without it? http://www.w8ji.com/mobile_antenna_fs_comparisons.htm and related links from that page... 73 Tom _____________________________
loading coil 23-33% the number resistance = Sometimes, but not always. As a general rule the hat has to be near the top of the radiator. Under some conditions when the hat is installed close to the
Tom Rauch wrote........ Message: 1 Date: Tue, 27 Sep 2005 11:11:36 -0400 From: "Tom Rauch" <w8ji@contesting.com> Subject: Re: [TowerTalk] Top hat on mobile usefull? To: <towertalk@contesting.com> Mes
I have a W6HIQ mobile antenna, the 4 inch, 160 meter version. Because of tooling limitations, the coil is limited to something like 12 inches. With the wire size W6HIQ chose, there isn't quite enoug
A lot of people are under the impression that the higher the current in a particular part of the antenna the greater the radiation from that part. That is not the case. In the instance of a quarter w
Gary, Thanks for the clarification. I forgot that when the energy becomes a detached EM wave, that that magnetic and electric fields become "mutually causal". So given that, then, is a few more feet
energy becomes a become "mutually effective height on 40m words, if one some height, would Dudley, I'm not sure what all that means, but radiation is a product of current over linear distance. In ot
Hi Gary, the current in from that I'm under that impression, as are all the textbooks and modelling programs I have. length at the open of that little in the Sorry, but I strongly disagree. It is a w
on 40m CW. I coil by using a that in order to coil. In your mitigate the possible I'm not sure what you are describing. Of course if you removed the electrical connection the hat wouldn't do much of
Radiation resistance increases along the length of an antenna. Higher radiation resistance means less current for a given amount of power. 73 Gary K4FMX ______________________________________________
antenna. Higher of power. Not so Gary. Radiation resistance associated with any particular antenna is a single value based solely on the radiation from the antenna system and the net or effective cu
Tom Rauch wrote.... Tom, Yes, the capacity hat was connected to the top of the coil with a wire. The extra delrin rod was merely to put some distance between the coil and the capacity hat in order to
coil with a wire. between the coil and coupling between the two. of the coil Q, I understand now. I don't think it would have a large effect either way. The capacitance of the hat should dominate th
Hi Tom, I agree with you on the definition of radiation resistance as being the equivalent resistance that a given amount of current passed through it causes an amount of power to be radiated. I squa
One interesting point is that the definition of radiation resistance has varied between countries and over time. It certainly was just 'the real part of the feed impedance' here about 50 years ago. P
wave antenna line. Just compared to the see any power Behind every EM field is an accelerating charge. Physics texts descibe radiation as being produced by charge acceleration. point then a half EM