ANTENTOP- 02- 2010, # 014

Grounded and Underground Antennas

Figure 147 Diagram of Directivity in the horizon plane of the Cable Underground Antenna

A For "Low" frequencies

B For "High" frequencies

(Note I.G.: At the article no explaining the "Low" and "High" frequencies)

Two Cable Underground Antennas may make a Zenith Underground Antenna. The antenna made similar to symmetrical spreading antenna shown on Figure 133 A.

Note I.G.: Zenith Antenna is common known as NVIS (Near Vertical Incidence Skywave) Antenna.

Underground Cable Antenna has length of the radiation part (L2 at Figure 146) approximately 10 meters. The length was found by practice. There is no sense to use radiation part with length more the 10 meters because far parts of the Underground Cable Antenna do not radiate efficiently.

To increase efficiency of the Underground Cable Antenna (Figure 146) the radiation parts L2 placed into the trench above dry sticks or straw. Then the same dry sticks or straw put on above the parts L2. So, antenna wire is placed inside dielectric sleeve. Ground is placed above the dielectric sleeve. Such design allows easy remove the Underground Cable Antenna from the trench.

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