[Antennas] Krazy Antenna Idea

2002年5月01日 17:59:09 -0700

OK, most seemmto say that elevating the antenna on the carport with the 
radials all over is a bad idea. So I should mount the antenna on the N 
side of the lot, near to the power line, run the radials in the lawn 
towards the W, E, & S.
Now the antenna. I would like it to be 33ft of Al irrigation tubing, in 
the new lacation guying will be less problem but, i think, near feild 
absorption will be, ie fences, carport, house, power, phone, and CATV lines 
to the N.
The tube would be insulated from the ground (maybe not if using some sort 
of a better match). Anyway, 33ft up, then the tube connected to the braid 
of coax (what type?), the coax about 66ft long, the braid on the end 
attqached to the centre, looped down the tube. The centre of the coax on 
the end attached to the tube attached to a whip as long as I can get it, or 
a wire running towards the carport to a pole mounted on the carport to the 
south.
I need to figure out the matching, preferable one that includes the gound 
for lighting and static electricity, to go to a 50ohm coax to the rig.
Am I the Emporer with out cloths or just the jsdter?
Comments please.
Chris opr VE7HCB
At 04:37 PM 2002年05月01日 -0500, you wrote:
>Radials that are in contact with the ground are detuned by the ground and
>need not be resonant. They are there to collect return currents within
>about 1/4-wavelength of the base of the antenna. Length is not critical -
>the more the better.
>>Radials that are elevated need to be resonant to be effective. That means
>that their length is critical as are their surroundings. They cannot lay on
>something like a carport roof that would detune them. They cannot be
>connected to ground or anything except an insulator at the far end. Snow
>will probably detune the radials, perhaps substantially.
>>A radial that starts out in the air, runs along a roof and then dives down
>to be connected to ground is not really a radial but an extended "ground"
>wire that is too long to have much effect.
>>I see little need to elevate the antenna for 160. Put it on the ground and
>put out as many radials as you can of whatever lengths you can fit into the
>property. More shorter radials are better than fewer longer radials. Snow
>will have little effect.
>>I would forget about the carport . . .
>>73/72/oo, George W5YR - the Yellow Rose of Texas
>Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
>Amateur Radio W5YR, in the 56th year and it just keeps getting better!
>QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
>Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
>>>Chris BONDE wrote:
> >
> > I have been planning on being on 160m. The upper portion, say 1850 to 
> 1975.
> > I have a carport that runs E-W, that is the length, the mountain to the N
> > fairly well prohibits propagation that way.
> >
> > If I mount a vertical on the N side of the carport, run the radials E-W on
> > the N edge, S-E and S-W to the diagonal corners, and, S on the width, with
> > possibly, the radials from the N wrapping along the edge to join the
> > diagonals which could go to the ground and be grounded, along with the
> > width N-S going to ground over the edge. This is the first question how
> > would that work for the radial system? How would the snow on the roof of
> > the car port, up to 4ft deep, dry and wet, influence the radials plus the
> > antenna. Now that is something else.
> >
> > __________________O________________________
> > ! / |
> > \ |
> > | / | \
> > |
> > etc
> > Any comments on this radial system?
> >
> > Chris opr VE7HCB