text: Chapter 6
  HIGH FREQUENCY, DIRECTIONAL, FIELD-EXPEDIENT
  ANTENNAS
  6-127. The long-wire (Figure 6-21) and vertical half-rhombic (Figure 6-22) are two field-expedient,
  directional antennas. These antennas consist of a single wire, preferably two or more wavelengths long,
  supported on poles at a height of 3 to 7 meters (10 to 20 feet) above the ground. The antennas will,
  however, operate satisfactorily at less than 1 meter (about 3 feet) aboveground. The far end of the wire
  connects to ground through a noninductive resistor of 500 to 600 ohms. The resistor should have a rating
  of at least one-half the wattage output of the transmitter. This ensures that the output power of the
  transmitter does not burn out the resistor. A reasonably good ground, such as a number of ground rods or a
  counterpoise, should be used at each end of the antenna. The radiation pattern is directional. The antennas
  are used primarily to transmit or receive HF signals. The "V" antenna is another field-expedient, directional
  antenna (Figure 6-23). It consists of two wires forming a "V" with the open area of the "V" pointing toward
  the desired direction of transmission or reception. To make construction easier, the legs may slope
  downward from the apex of the "V." This is called a sloping "V" antenna (Figure 6-24). The angle between
  the legs varies with the length of the legs in order to achieve maximum performance. To make the antenna
  radiate in only one direction, add noninductive terminating resistors from the end of each leg (not at the
  apex) to ground. The resistors should be approximately 500 ohms and have a power rating at least one-half
  that of the output power of the transmitter being used. Without the resistors, the antenna radiates
  bidirectionally, both front and back. The antenna must be fed by a balanced transmission line.
  Figure 6-21. High frequency antenna, long-wire type.
  Figure 6-22. High frequency antenna, half-rhombic type.