On 7 Feb 2004 01:23:13 -0800, (Mark Keith) wrote:

Cecil Moore wrote in message

I do think it's quite normal to have a slight taper, ....

Then you disagree with the guys who say it has no taper. Guess what,
Mark? That puts you on my and Yuri's side of the argument.

Maybe so, but I place much less importance on this than he does. To
me, it means very little, if anything. It surely will not effect how I
will design mobile antennas. After all, as Wes pointed out on his web
page, the change in radiation resistance is what really improves the
efficiency of a short loaded antenna. Not the current distribution in
itself. The improved current distibution is just a method used to
change the radiation resistance. Taper or no taper, in the usually
short 1 ft or so space a coil would occupy, "1/8 the length of a 8 ft
whip" the difference either way is not worth worrying about. And the
worrysome taper is only in the upper section of the coil, so really
it's less than 1/8 of the total antenna length. Most of the plots I
see are more bow shaped than a gradual taper due to the peak in
current. I'm glad Wes commented on the current peak...This was
something I had seen previously in modeling the antennas/coils a few
weeks ago, and had wondered about..
If we could do away with the high ground losses, we wouldn't need to
elevate the coils, or use hats. That's why often a base load 10-11m
vertical on a large car roof is about as good as a center load. Less
ground loss due to the better psuedo ground plane under the antenna.
MK

You show that nothing has changed in three months:

Hi Mark,

I offered an EZNEC analysis that supported (circumspectly) Yuri's
position, but he blew it off chasing rainbows. Using the protocol
(already published by Yuri) for emulating a solenoid (and not just the
contentious one point load), that solenoid is found residing on
segments 50 to 59 (spanning 10 inches):
1 W2E1 1 0.00
2 .95623 0.00
3 .9205 0.00
4 .88976 0.00
5 .86122 0.00
6 .83415 0.00
7 .80815 0.00
8 .78296 0.00
9 .75843 0.00
10 .73443 0.00
11 .71088 0.00
12 .68771 0.00
13 .66486 -0.01
14 .64229 -0.01
15 .61997 -0.01
16 .59787 -0.01
17 .57596 -0.01
18 .55421 -0.01
19 .53261 -0.02
20 .51115 -0.02
21 .48979 -0.02
22 .46853 -0.02
23 .44736 -0.02
24 .42627 -0.02
25 .40523 -0.02
26 .38424 -0.02
27 .36329 -0.02
28 .34238 -0.03
29 .32148 -0.03
30 .30059 -0.03
31 .27969 -0.03
32 .25878 -0.03
33 .23785 -0.03
34 .21688 -0.04
35 .19585 -0.04
36 .17477 -0.04
37 .1536 -0.05
38 .13234 -0.05
39 .11095 -0.06
40 .08941 -0.07
41 .06769 -0.08
42 .04576 -0.12
43 .02355 -0.21
44 .001 -4.38
45 .02202 -179.8
46 .04579 180.00
47 .0707 180.00
48 .09404 180.00
49 .11529 180.00
50 .13404 180.00
51 .14984 180.00
52 .16235 180.00
53 .17155 180.00
54 .17718 180.00
55 .17057 180.00
56 .15943 180.00
57 .15069 180.00
58 .1433 180.00
59 .13668 180.00
60 .1306 180.00
61 .12495 180.00
62 .11962 180.00
63 .11457 180.00
64 .10975 180.00
65 .10512 180.00
66 .10066 180.00
67 .09634 180.00
68 .09216 180.00
69 .08809 180.00
70 .08413 180.00
71 .08025 180.00
72 .07646 180.00
73 .07274 180.00
74 .06908 180.00
75 .06549 180.00
76 .06194 180.00
77 .05845 180.00
78 .05499 180.00
79 .05158 180.00
80 .04819 180.00
81 .04484 180.00
82 .0415 180.00
83 .03819 180.00
84 .03488 180.00
85 .03159 180.00
86 .02829 180.00
87 .02499 180.00
88 .02167 180.00
89 .01831 180.00
90 .01491 180.00
91 .01141 180.00
92 .00777 180.00
93 Open .00363 180.00


I will not hesitate to point out that the variation in signal strength
between the point load and the distributed load varied by
one-quarter dB
Which represents ALL the steam in the claim of outrageous losses due
to EZNEC's (pilot error) inability to model correctly.

73's
Richard Clark, KB7QHC