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Tests done by J.S. Belrose (1994) [7] showed that though the conventional T²FD length is close to a full-size 80 meter (3.5–4.0 MHz) antenna, the antenna starts to suffer serious signal loss both on transmit and receive below 10 MHz (30 m), with the 80 meter band signals −10 dB down (90% power loss) from a reference dipole at 10 MHz.
German physicist Heinrich Hertz first demonstrated the existence of radio waves in 1887 using what we now know as a dipole antenna (with capacitative end-loading). On the other hand, Guglielmo Marconi empirically found that he could just ground the transmitter (or one side of a transmission line, if used) dispensing with one half of the antenna, thus realizing the vertical or monopole antenna.
If the several dipole pairs are near the same length, the antenna will show a continuous range of matched-impedance frequencies wider than any one dipole. If the dipole pairs' lengths have wider size differences, the fan dipole will show multiple distinct resonant frequencies, at least one resonance for each pair.
(The term "linear" is not strict: End-sections of a linear antenna far from its center can be bent away from a straight line with only slight or unnoticeable loss in performance.) Dipole Two-armed antennas, like "rabbit ears". For resonance, each arm is slightly under a quarter-wave base to end, which makes the whole antenna nearly a half-wave ...
As can be seen in the above table, for linear antennas shorter than their fundamental resonant length (shorter than 1 / 2 λ for a dipole antenna, 1 / 4 λ for a monopole) the radiation resistance decreases with the square of their length; [24] for loop antennas the change is even more extreme, with sub-resonant loops ...
Loop antenna, receiver, and accessories used in amateur radio direction finding at 80-meter (260-foot) wavelength (3.5 MHz). As long as the loop perimeter is kept below about 1 / 4 wave, the directional response of small loop antennas includes a sharp null in the direction normal to the plane of the loop, so small loops are favored as ...
US Postal Service employees work inside the Los Angeles Mail Processing & Distribution Center on December 3. The facility is currently processing 1 million packages per day.
This simplified arrangement has several advantages, including a shorter ground distance between the ends. For example, a dipole antenna for the 80 meter band requires a ground length of about 140 feet (43 m) from end to end. An inverted vee with a 40-foot (12 m) apex elevation requires only 115 feet (35 m).