All of us are familiar with various types of dipole antennas like inverted V and horizontal dipole antennas. What about monopole antenna? It is the original antenna invented by none other than Marconi way back in 1895! But Marconi himself had made changes from his original description. Monopole antenna is also called Marconi antenna. Tall monopole antennas are used by broadcast stations where the tower is the radiating element connected to the transmitter and the ground plane is formed by a system of cables buried under the ground.
Ham radio operators are familiar with two types of monopole antennas. One is the universal Rubber Ducky seen on most hand held radios. Rubber ducky is an electrically shortened antenna with a helical wire inside which gives a distributed inductance to cancel the capacitance of an electrically short antenna. Second is a ground plane vertical antenna with radials which serve as the ground plane. Usually ground plane antennas are of quarter wavelength of the operating frequency. 5/8 wavelength vetical antenna radiates maximum power in the horizontal direction and is useful for local contacts on VHF and UHF.
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