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Amateur Station A was located in a multi-story condominium townhouse. Three antenna systems were surveyed at this station. Measurements were also made at the location normally occupied by the operator during transmission, which was in the first floor garage of the townhouse.

(1) Half-sloper Antenna

The first antenna system studied was a bottom-fed quarter-wave wire antenna of the type referred to as a "half-sloper." This type of antenna consists basically of a wire strung between the ground and some higher point so that the wire has a particular slope with respect to vertical and is essentially one-half of a dipole operated against ground. The antenna studied was separated into sections by "traps" to allow quarter-wave, resonant operation at four different frequencies: 7, 14, 21, and 28 MHz. The total length of the antenna was about 14 meters (m). The upper end of the antenna was supported by trees near the condominium building with the lower end attached to a ground rod. Six ground radials extended about 8 m from the ground rod in a soil strip between a masonry wall and parking lot pavement. The parking lot separated the building from the antenna and trees. The results of electric and magnetic field measurements at various distances along three radial lines at 1 meter above ground are given in Tables 5 and 6.

(2) Attic-mounted Dipole Antennas

A second antenna system at Station A consisted of dipole antennas located in the attic of the townhouse above a top-floor bedroom and stairway. Three different horizontal, half-wave, resonant, dipole antennas met at their centers where they were fed. The three antennas were resonant for 14, 21, and 28 MHz, respectively. Electric and magnetic fields measured in the rooms below the dipole antennas are given in Tables 7 and 8.

(3) Attic-mounted Discone Antenna

A VHF/UHF "discone" antenna was mounted in the attic, near the dipole antennas. This antenna was designed for transmitting at frequencies between 50 and 1300 MHz. At Station A it was primarily used for transmitting at 50, 144, 220, and 440 MHz. Field measurements results using the discone antenna are given in Table 9.


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