HORIZONTAL DIPOLE ANTENNA (SKIP / DX USE ONLY)
This is the most simple and inexpensive antenna for CB radio use. It is often underestimated, specifically because it is a skip / DX only antenna. It's local performance is relatively poor, while it's skip / DX performance can be quite surprising.
In the past I installed a 1/4 wave ground plane antenna and half wave horizontal dipole antenna at the same height. I connected both antennas to an antenna switch box that was connected to the CB radio. When skip conditions were active I switched back and forth between the two antennas to compare signals. Quite often the flat-side dipole antenna received signals that the vertical antenna could not receive. When both antennas received the same signal, the horizontal dipole was nearly always the clear winner.
Vertical antennas are inherently noisy, as most 'local noise' (interference) is vertically polarized. In instances where vertical and horizontal antennas are receiving the same signal at the same signal strength, the audio is often more clearly received by the horizontal antenna, simply because the noise floor is much lower on the horizontal antenna.
Considering transmit ability, in many instances the horizontal dipole antenna will outperform a half wave vertical base station antenna, simply because the horizontal dipole is directional. The antenna transmits in two directions off the side of the wire. For example, if the sides of the wire antenna are facing north and south, most of your transmit power will be directed north and south. Setting up two horizontal dipole antennas with an antenna switch-box would be quite powerful, allowing you to switch between north/south and east/west.
Any 50 ohm coaxial cable will work. RG-58, RG-8X, RG-213 etc. You can use any type of wire for the actual antenna. It does not matter how thin or thick the wire is. It does not matter if the wire is stranded or solid. It does not matter if the wire is copper or steel. The difference between these types of wire is trivial on HF frequencies. (27MHz CB Radio)
The insulators should be made out of something that does not conduct electricity. Rubber, plastic or even wood. It's also acceptable to tie the rope or fishing line directly to the wire.
One of the 105 inch wires connects to the center wire of the coax. The other wire connects to the shield / braid of the coax. You must insulate these connections to ensure that they do not touch each other. Electrical tape will do nicely.
Ideally you want to mount this antenna at least one wavelength above the ground. At 27MHz CB radio this is 34 feet. However, you will obtain ample results with the antenna mounted at least a quarter wavelength above the ground. (105 inches)
To obtain the most optimum VSWR (voltage standing wave ratio) while transmitting with this antenna, you can start by making both pieces of wire 108 inches long, and then trim one inch off of each wire until the best SWR is achieved. After making several of these antennas, 105 inches was most often the magic number.
If you are interested in making a more advanced dipole, and / or if you plan to run a significant amount of power through this antenna, you may want to install a 'one to one balun'. (1:1 balun) The coax connects to the base of the 1:1 balun and each antenna wire connects to the two connections on the side of the balun.
FLAT-SIDE HALF WAVE DIPOLE ANTENNA
HORIZONTAL DIPOLE CB RADIO ANTENNA
FLAT-TOP DIPOLE ANTENNA FOR DX CB RADIO
The 1:1 balun isolates the antenna from the coaxial cable, preventing the coax from radiating part of the transmitted signal. The 1:1 balun is also called an 'RF Choke'.
In my personal opinion the 1:1 balun is not needed in this cheap and easy antenna project, because if you are going to run more power and get more technical about an antenna, you might as well invest in an antenna that is proven to provide good local and DX performance.