End Fed Antennas
A very simple antenna to make, deploy and use is an end fed wire antenna. The number of variations are endless. Probably the most familiar is the end fed half wave antenna (EFHW) But random length or non-resonant end fed antennas are also popular and effective, especially for portable use. Both can be used on multiple bands though the random length one may have a slight advantage there if you have a tuner. Just a note, as with most antennas, you will find more opinions about end fed's than there are people to have them. My advice is, try them. What works for you in a particular situation is what is important.
As most authors note, random length doesn't generally mean just any length with the issue being that the wire shouldn't be resonant on any desired frequency. Some often used lengths are 29ft, 35.5 ft, 51 ft and 84 ft.. Most include 4:1, 9:1, 49:1 or other transformer, balun or unun attached between the antenna and a coax feedline which in turn goes to a tuner or directly to the radio. However, depending on the capability of your tuner you may be able to attach the radiator and counterpoise directly to the tuner and avoid the unun. Except for the EFHW a counterpoise is always necessary. The length of the counterpoise is not critical. I have found that a 17 ft counterpoise works well with a 29 ft radiator. An end fed antennas whether random or resonant can be set up in various configurations such as a sloper, a vertical, inverted L, etc. making them very convenient and attractive. They are particularly suited for use in portable situations.
A special case of the end fed antenna is the end fed half wave antenna. It is essentially a half wave length of wire fed at one end rather than in the middle as would be the case with a dipole. Its radiation characteristics are similar to a half wave dipole. They have to main attractions: 1) ease of setting up and feeding since only one support for the far end is essential. The driven end can literally be just inches or feet off the ground. 2) they can be used without a tuner on all harmonically related bands above the design band. So one cut for 40 meters can be used with no tuner on 40, 20, 15 and 10 meters. A negative is that they generally require a transformer, typically a 49:1 transformer to bring the approximately 2500 ohms impedance at the feed end down to 50 ohms. My experience is that transformer is a small price to pay for a very convenient and effective antenna. I currently use an mfj 1984MP, 40-10 efhw as my primary home station antenna. It replaces a G5RV which has served me very well for many years and may go back up again.