I wish amateur radio wasn't quite so complex!...
Well, it is by nature, and it doesn't have to be in practice.
A simple dipole antenna will get you on one band quickly with a minimum of effort.
You can make it yourself with a bit of wire.
You can add a dipole for a second band to the original antenna so it works two
bands - say 20m and 15m. By starting with the wires a bit long and trimming the
ends you can get the SWR down to where you don't need a tuner.
Where things tend to get complicated is when someone wants a single antenna
that has good performance on all the bands their radio covers - such as 160m to 6m.
That sounds convenient, but the radiation pattern likely won't be optimum for all
the bands. That, and other tradeoffs, is why there are so many multi-band options,
and they all have their pros and cons.
But you aren't limited to one antenna - often it makes more sense to have several
that are optimized for different bands or paths rather than try to make one do all
jobs.
And anyway, I've never put up an antenna before!
Let's start there. Every ham starts out not having put up an antenna. Then most of them
do. There is a lot of practical knowledge involved, but it is mostly a matter of mechanics.
A good way to start is to join the local radio club and ask for assistance. The "antenna
party" used to be a great ham tradition: you get several hams together to help put up
your antennas (or you go along to help others) and then have lunch or drinks afterwards.
You make some friends and learn a lot, your antenna gets put up and you get some help
on how to operate the rig, tuner, etc. You may even find a local with a pile of scrap
wire for building antennas.
Not that you can't get started all by yourself - many of use did that. But if there is a
local club it makes life easier.
...would like to make some DX contacts using a simple antenna..., firstly which bands would be best to focus on for long distance contacts...
I'd start with 20m. It is THE band for DX. Not that other bands aren't often as good, or better,
at times, but if you only had one band, that probably is the best choice.
Conditions change over time. We've just come out of an extended dip with low sunspot numbers,
where propagation was nearly non-existant on the higher bands. But things are getting much
better, and we're even seeing openings on 10m. The higher bands -when they are open - give
better signal strengths for DX. So 15m and 10m are good second choices, as well as 17m
(which has less activity, and isn't as full of contests), though just a year ago there wouldn't
have been nearly as much activity. A single antenna that you can use on 20m through 10m
isn't difficult.
40m is different in Europe than on this side of the Pond, where the band is 300kHz wide and
we don't have to contend with nearby SW BC stations. You'll have to try it and see if it is
to your liking. 80m provides a lot of local contacts. DX is possible on both bands, but takes
more work. The same goes for Top Band (even more work.)
and then what kind of wire antenna would be best?
There are two basic approaches to wire antennas.
The first is to tune the antenna to give a good match to common coax cable. The dipole
antenna I recommended above is an example. Once you've done that, the antenna will
work without a tuner on the design band, and sometimes the 3rd harmonic (typically
using a 40m dipole on 15m.) You can add additional wires to the feedpoint to give you
coverage of more bands - I've often set up my portable antenna kit to cover 80, 40, 20,
15 and 10m at the same time. This approach is convenient because you don't have
to bother with the antenna when you change bands. There are several different ways
you can make an antenna work on multiple bands, such as adding traps, etc.
The other approach is to put up a wire antenna and use a tuner to match it on all
bands of interest. This requires a tuner, but simplifies antenna construction. The
most common example is to put up a dipole of any convenient length fed with
ladder line or twin lead to the tuner in the shack. That allows you to use a simple
antenna on multiple bands, with the added cost of a tuner. (Which you can also
build yourself if you want.)
Both approaches work. Some people find one more convenient for their preferred
operating style than the other. The main problem comes when people try to combine
the two methods by feeding an untuned antenna with a tuner through a coax line - the
line losses can be very high. Not that you won't still make some contacts, but you may
be losing 50% to 90% of your power in the feedline before it reaches the antenna.
That's why the untuned antenna uses ladder line - it can operate over a wide range
of impedances with low losses.
Unfortunately, many antennas sold as working "all bands" don't necessarily do so very well.
You'll get a lot of different responses on this matter. The standard (31m) G5RV with coax feed to
a section of twinlead should work reasonably well on 80m, 40m, 20m and 12m. It will tuner on
some other bands, but losses may be higher, depending on your choice of feedline and the length.
There are variants of the Off-Center Fed Dipole ("OCFD", sometimes mistakenly called a "Windom")
that are also advertised to cover all bands. They may do a good job on several of them. With both
of these you most likely will need a tuner.
Another option is a horizontal loop - one for 40m and up will be 10m on a side. This makes a nice
all-band antenna, though it requires more support points than a simple dipole. When fed with a
4 : 1 balun at the feedpoint you can get 40, 20, 15 and 10m with usable SWR, or you can use
open wire line to a tuner in the shack for all-band coverage.
But I'd still recommend starting simple to get on the air while you read more about other options
and plan your next antenna.
One other thing to remember is that, with horizontal antennas for working DX, they will work
better the higher in the air you can install them. So give some thought to what you have
available for antenna supports. A good target would be to get your antenna up 10m, but
if you can't manage that, just do the best you can.
Verticals are interesting, but seem more complex to erect in a very windy area (and my area is exceptionally windy!), and to tune.
Not necessarily any worse than other antennas. They can be self-supporting, which comes
in handy if you have no local trees to string wires from. They typically require a good earth
radial system for high efficiency, but you can use some lengths of dural tubing or a wire hanging
from a fishing pole or tree branch. Much of the discussion you have read about tuning them
is related to the multi-band versions with traps, but again you can put up your own simple
vertical for one or two bands with much less effort.
I can only apologise for my ignorance, but at least I'm trying to do something about it by learning from others, rather than reinventing the wheel as a square!
Not a problem - we all started from that point at some point in our lives. (And some have
never moved on from there.) Once you get a feel for the mechanics of putting up an antenna
(such as throwing a rope over a tree branch, or installing a mast of some sort, tying knots, etc.)
then putting up an antenna doesn't need to be a lot of work. If you use halyards at each end
it becomes simple to take one antenna down and try another to see which works better.
