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A HB9XBG Full Size Vertical Antenna for the 40m-band on Simplon Pass with view to Mount Fletschhorn. The 40-meter or 7-MHz band is an amateur radio frequency band, spanning 7.000-7.300 MHz in ITU Region 2, and 7.000-7.200 MHz in Regions 1 & 3. It is allocated to radio amateurs worldwide on a primary basis; however, only 7.000-7.200 MHz is ...
Moxon antenna for the 20-meter band.The antenna is the faint rectangle of wires held in tension by the bent X-shaped support frame. Moxon antenna for the 2-meter band. The Moxon antenna or Moxon rectangle is a simple and mechanically rugged two-element parasitic array, single-frequency antenna. [1]
AT&T 2 wire rhombic in Dixon, California, in 1937, used for telephone service to Shanghai, China. The rhombic antenna was designed in 1931 by Edmond Bruce [1] and Harald Friis, [2] [3] It was mostly commonly used in the high frequency (HF) or shortwave band as a broadband directional antenna.
A quad antenna is a self-resonant loop in a square shape; this one also includes a parasitic element.. Loop antennas may be in the shape of a circle, a square, or any other closed geometric shape that allows the total perimeter to be slightly more than one wavelength.
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.
In electromagnetism, an eddy current (also called Foucault's current) is a loop of electric current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes ...
Orr (1996) [13] shows a 10, 15, and 20 meter, 2 element quad with boom length of 6′10″. Internally stackable Interaction between antennas of a multiband quad are quite low, even when fed with a single feed line, [ 14 ] so higher frequency (smaller) quad loops can be nested in lower frequency (bigger) quad loops, allowing operation on as ...
A small loop antenna, on the other hand, has lower radiation resistance [b] and is not self-resonant; it requires some form of impedance matching to counter the loop's reactance – in practice, this usually consists of a variable capacitor bridging the point corresponding to the gap of a halo. Connection diagram for a gamma matched halo antenna.