In reply to M6HBS:
The only problem with asking your original question about what antennas do people use and find best is that it will be almost impossible to find a consensus. Ask 100 people and get 100 differing opinions and experiences.
Portable antennas, by their very nature, have to be a compromise between efficiency, durability and practicality; so a very wide set of variables to contend with.
What I have found is it can be quite difficult to replicate some designs you find on the web. Often it is down to simply not being able to find exactly the same wire, cable or co-ax as the original design; these can have significant effect on performance; all this means is that you have to do quite a bit of experimenting.
Personally I don’t like using tuners if I can help it, especially portable. Tuners are just another piece of equipment to fail, get wet or just not do what you want. So All of my antennas are simple (ish) and resonate where I want.
From my experience, low slung inverted V dipoles (with an apex about 5m) are fine for the lower bands like 80, 60 and 40m during the autumn, winter and early spring. 60 and 40m low dipoles are ok during the summer when there is plenty of sporadic E about. 80 metres is just too unreliable during the summer, sometimes it works very well but I tend to not bother too much with that band unless it is first thing in the morning or late in the afternoon. For 20m and up I just feel they are too compromised in their radiation patterns, not saying you cannot get contacts on those bands because people do.
40 metres is my crossover band I have both dipoles and verticals for this band (the band can sometimes be unreliable during summer); below I only use diploes above only verticals. My reasoning is, for bands like 80, 60 and 40m low dipoles give an omni-directional pattern with the maximum amount of energy going straight up to take advantage of NVIS propagation. On 40m and upwards I want my signals to have a much lower take off angle for maximum coverage; ground mounted verticals appear to provide this better than low dipoles.
During the summer my main antenna is a vertical 9.5m (ish) piece of wire (with 3 9.5m radials) supported by a 10m fishing pole. This simple arrangement performs very well on 40m. I use the same piece of wire and load it with a length of 450 ohm ribbon to turn it into a ½ wave at 20m, again very simple with no tuner. I also load the same piece of wire (with a co-axial stub) to get a 5/8 wave vertical on 17m, this configuration gave me and Robert (G0BEB) possibly the greatest distance S2S, so far, when I was on a summit in Germany and Robert was on The Falklands.
I have been experimenting (with some success) with a combined 15, 10 and 6m ground plane antenna with raised radials (15 and 10m ¼ wave and 6m 5/8 wave). The only problem with these bands is that you have to be in the right place at the right time to get contacts, propagation is often very unreliable; but when they are open DX can be very easy.
So going back to the beginning, for the bands you want to use and from my experience; no tuners, verticals and try to choose the right band for the right time of year/time and experiment loads.
Another thought (something I do), check the data base for what contacts people make on which bands at which time of year and time of day. Find who has the most reliable contacts then find out what they are using in the way of modes, antennas and power levels (most of mine are in the 10 to 30 watt range, using Li-Po batteries and only use ssb).
Have fun/frustration (delete as appropriate)