The questions in this section were unchanged.
Another type of directional antenna is the log-periodic antenna. It is called this because for a log periodic antenna, the length and spacing of the elements increases logarithmically from one end of the boom to the other. (G9D07) The gain of a log periodic antenna is less than that of a Yagi, but an advantage of a log periodic antenna is wide bandwidth. (G9D06)
The term “NVIS” means Near Vertical Incidence Sky wave when related to antennas. (G9D01) An NVIS antenna is typically installed between 1/10 and 1/4 wavelength above ground. (G9D03) An advantage of an NVIS antenna is high vertical angle radiation for working stations within a radius of a few hundred kilometers. (G9D02)
A Beverage antenna is a very long and low directional receiving antenna. (G9D10) An application for a Beverage antenna is as a directional receiving for low HF bands. (G9D09) A Beverage antenna is not used for transmitting because it has high losses compared to other antennas. (G9D08)
Many antennas are designed for a single band, but in many cases, putting up an antenna for each band you want to operate is impractical. So, many amateurs put up antennas that will work on more than one band. These are called multiband antennas. A disadvantage of multiband antennas is that they have poor harmonic rejection. (G9D11)
One type of multiband antenna is the trap vertical. Antenna traps block RF energy in a certain frequency band. This makes the antenna look shorter than it really is at that frequency. The primary purpose of antenna traps is to permit multiband operation. (G9D04)