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A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. [1] [2] The current from the transmitter is applied, or for receiving antennas the output signal voltage to the receiver is taken, between the monopole and the ...
A whip antenna is an antenna consisting of a straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter. A whip antenna is a form of monopole antenna. The antenna is designed to be flexible so that it does not break easily, and the name is derived from the whip-like motion that it exhibits when ...
Although these antennas are enormous compared to a human, at 15 kHz the antenna height is still only about 0.015 wavelength, so paradoxically, huge VLF antennas are electrically short. From the table above, a 0.015 λ monopole antenna has a radiation resistance of about 0.09 Ohm.
It is shaped like the Greek letter Π or an upside-down capital letter U, and is the loop antenna analog of a ground-mounted monopole antenna. Similar to how a vertical monopole uses its ground system to produce a "phantom" image of the rest of a dipole, the missing lower half of the half-loop is replaced by its image in the ground-plane. If ...
A 1 / 4 λ monopole antenna and its ground image together form a 1 / 2 λ dipole that radiates only in the upper half of space. The vertical, Marconi, or monopole antenna is a single-element antenna usually fed at the bottom (with the shield side of its unbalanced transmission line connected to ground). It behaves essentially ...
The vertical antenna is a monopole antenna, not balanced with respect to ground. The ground (or any large conductive surface) plays the role of the second conductor of a monopole. Since monopole antennas rely on a conductive surface, they may be mounted with a ground plane to approximate the effect of being mounted on the Earth's surface.
The folded unipole antenna is a type of monopole mast radiator antenna used as a transmitting antenna mainly in the medium wave band for AM radio broadcasting stations. It consists of a vertical metal rod or mast mounted over and connected at its base to a grounding system consisting of buried wires.
It is the most efficient antenna design found so far for this frequency range, achieving efficiencies of 70-80% where other VLF antenna designs have efficiency of 15-30% due to the low radiation resistance of the very electrically short monopole. [8] The antenna was invented by Boynton Hagaman of Development Engineering Co. (DECO) and first ...