On 28 Jun 2004 23:26:37 -0700, (The Eternal
Squire) wrote:

Hi,

In my continual search for a halfway decent DX antenna situation for
20, 30, or 40 meters, I noticed that I have a carport approximately
120 feet long and 7 feet high and 15 feet wide. My car is at the very
end of the carport, right across from my apartment, and my apartment
is located on the lower floor.

Hi Andrew,

Unless this a continuation of your concern for stealth, I would
suggest a GAP vertical antenna. However, the remaining discussion
will presume your former interest.

The carport has florescent lights underneath every few cars, but is
stuck in the asphalt and is therefore not connected to any ground! I
am wondering if there is anything I can do with this?

Suffer comes to mind. There is a ground (code demands it), however,
it is a safety ground that in this case will probably not offer much
RF relief. However, this presumes the lights are noisy which is not
always the case. Most of this noise is through conduction and sharing
of power circuits. To determine how much is over-the-air, simply
scout the area with a small SW receiver with a whip antenna. Choose a
set of frequencies to monitor (the ones you want to work would be
suitable) and build a map of noise vs. frequency vs. position along
this carport. There is no more successful answer to your query than
direct experience.

1) Load up as is and work against a cold water pipe right underneath
my apartment. Long wire?

This will probably do just as well as any more elaborate design
(including my already mentioned GAP).

2) Lay one insulated wire on top of the carport, terminate the wire
at the far end with a resistor connected to the entire carport as
artificial ground, and load up the local end. Classic single wire
Beverage? Maybe two wires steerable Beverage?

A Beverage is typically a very low sensitivity and low efficiency
antenna that has the advantage of directional selectivity (AKA receive
antenna). It would have to be several wavelengths long to achieve its
vaunted attributes.

3) Because florescent lights cause RFI across the entire band, lay a
loop of very thin coax on top of the carport, interrupt the shield at
the near end in order to connect with my tuner, and connect the shield
to the carport and the water pipe for ground. Very long magnetic
loop antenna with vertical lobes?

Uhm, "magnetic" antennas will work quite well in picking up noise,
especially the way you have described it.

How good would any of these ideas be, or do you have any other ways to
exploit a carport?

You are in a far better position to simply try and report back here
how it went - anything else is conjecture of the first water and would
save you nothing in effort.

Another alternative is to find about 100 to 200 feet of coax. Add a
choke to the far end. Build a simple 1 Meter loop and attach it to
the choke. Connect the other end to your rig. Get a buddy and two
HTs so data can be accumulated. Walk the area and map out the
interference levels over several bands (a variation of the mapping
described above). A bigger loop, such as you anticipate, will only
suggest more noise introduced - if you can't live with a small loop's
worth, you certainly won't find any relief with a bigger one. As a
cautionary note, making it a small dipole won't bring any more relief
either. Noise, such as you anticipate, is noise - indistinguishable
from DX.

73's
Richard Clark, KB7QHC