Just a few comments..

- When receiving only the important part is to have a good signal to
noise ratio. HF is always pretty noisy and pretty well never below the
receiver noise floor. Antenna design for HF RX needs to consider
reducing noise as well as increasing signal.

- A dipole has a maximum response at right angles to the wire. This ONLY
applies if the dipole is a half wavelength long and is centre fed. (Some
pattern skewing will normally be evident with an end fed dipole in the
direction away from the feedpoint) A piece of wire one wavelength long
will tend to exhibit maximum responses at about 45 degrees to the wire.
ie there will be 4 lobes in the horizontal plane. You see then that it
isnt simple to give a straight answer on this. Whatever frequency you
choose for the particular wire length you will get varying patterns. You
can of course cut the antenna for the band of interest.

- Vertical antennas tend to be noisier than horizontal antennas. (ie
they pick up more local man made noise)

- There is no reason why you cant mount a dipole vertically or even
diagonally. It is important though to have the feed line at right angles
to the wire for some length. The pattern is of course affected by this
orientation. When it is vertical it will tend to radiate equally in all
(horiz) directions. You should also consider the ground as a kind of
lossy reflector.

- You might like to look at a folded dipole antenna. I have heard the
claim that they are less noisy than a single wire dipole. Suggest you
have a look at Mr Cebik's TFDP on http://www.cebik.com/wire/wbfd.html

- Two parallel elements will generally speaking look like a continuation
of the transmission line and not radiate/receive as effectively. It
depends on the spacing though. You can tune the distance apart so that
some gain in a particular direction/directions will occur. I would
suggest you keep away from this for general HF use.

- A right angled dipole (lookup "Inverted V") with the feedpoint at the
highest point is a valid design. I'll admit I havent researched it but
anecdotal comments to me in the past say it works much better than a
dipole with a lower feedpoint but same average height.

- Yes a long wire can be bent. It is surprising (to me) how much it
doesnt affect directivity. (Assuming the bends arent too great!) You may
wish to model this kind of thing (and other antenna designs) using
Eznec/4NEC2 etc. Its all very fascinating.

- A wire in a horizontal V shape will tend to radiate/receive more in
the direction of the open end of the V. Once again though for varying
frequencies/lengths this behaviour will be variable.

- Yes you can connect more than one wire to the RX at one time. There
will of course be interaction depending on their length and usage
frequency. You may get a useful directive pattern or something that is
useless.

- If you want to monitor a specific spot frequency on HF I would suggest
a single quad loop.

- If you really want to fiddle with a sharply tuned low noise antenna
have a look at magnetic loops. They can usually be made to cover a 2:1
(or more) freq range and maybe what you are after for RX only purposes.
The signal strength will be lower than (say) a dipole but the signal to
noise will be much greater. (anecdotal knowledge)

- Make sure your station grounding is good. For noise reduction as well
as safety. You may also want to check your house appliances for noise
creation and suppress them. Keep in mind that at the distance you
currently have to ground that looks like a 1/4 wave on about 7Mhz, 3/4
on 21Mhz etc and thus a high impedence path. ie the noise volts in the
system (at those freqs) wont flow well to ground through this path. In
fact any other noise that exists on the water pipe ground from other
sources may interfere. Whether running a separate piece of braid/wire
will help is an unknown. It depends on a number of variables, but it
cant however hurt to try. Also ensure that power and other boxes
connected (eg a computer for digi modes) are single point earthed and
isolated accordingly. (eg if you are using a soundcard to demodulate
digi signals make sure there is (say) transformer coupling between the
radio and computer)

Hope this is helpful. My suggestion would be a WBFB as big as will fit
in your yard, maybe bending some of it to fit. Also keep the feedpoint
high (ie inverted V construction) Also run a thick braid earth from your
station to a seperate ground stake. Read up on this espcially in the
area of grounding RF rather than just safety issues. Then bond that
stake to your electrical ground as well (ie outside the house)

Cheers Bob W5/VK2YQA East Texas

Birderman wrote:
Hi,

Being a Newbie, in West London, to this hobby of SWL, I am seeking advice on
best antenna to use.