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Arnold B. Bailey was granted the US patent 2,184,729 Antenna System on December 26, 1939, after filing in 1937 for a vertical antenna providing coaxial element sleeve structures.
Folded dipole Double-wire dipole whose characteristic impedance in free space is around 300 Ω. Dipole Although the center impedance at resonance is approximately 73 Ω in free space, in actual use it varies between 30 and 100 Ω, depending on height above ground, so with high-impedance feedline a T-match or Y-match feed will probably be necessary.
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
The HB9XBG antenna is a vertical dipole antenna for short wave radio amateurs. It was developed by the Swiss radio amateur Walter Kägi, whose call sign HB9XBG is also the designation of the antenna. [1] During the test phase in 2020, HB9XBG built two vertical dipoles – one for the 20-metre amateur radio band and another for the 40-metre band.
Moore describes his antenna as "a pulled-open folded dipole". While the main point of Moore's patent was the two-turn single loop design, which is not the antenna termed "quad" today, the patent does include a mention and illustration of a two-element unidirectional "quad", and describes the time when the full wave loop concept was developed:
The 1972 Doubled Die cent is worth a pretty penny,” said Pearlman, sharing that the Numismatic Guaranty Company Price Guide “estimates the current retail value at $175 in Extremely Fine ...
The coil is added at the base of the whip (called a base-loaded whip) or occasionally in the middle (center-loaded whip). In the most widely used form, the rubber ducky antenna, the loading coil is integrated with the antenna itself by making the whip out of a narrow helix of springy wire. The helix distributes the inductance along the antenna ...
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).