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The biconical antenna has a broad bandwidth because it is an example of a traveling wave structure; the analysis for a theoretical infinite antenna resembles that of a transmission line. For an infinite antenna, the characteristic impedance at the point of connection is a function of the cone angle only and is independent of the frequency.
The antenna is fed power between the bottom of the mast and ground so it requires a grounding (Earthing) system under the antenna to make contact with the soil to collect the return current. One side of the feedline from the helix house is attached to the mast, and the other side to the ground system.
Channel Master's original product was a prefabricated television aerial with hinged elements which would unfold and snap into place; this patented design greatly reduced installation time as existing antenna designs at the time had to be bolted together from multiple pieces by rooftop installers. [17]
The station's current antenna was built in 1972; it consists of two guyed masts, each 458.11 metres (1503 feet) tall, which are configured as umbrella antennas. They are fed by an overhead cable, fixed to a tall mast at one end, and at the opposite end to a smaller grounded mast near the helix building via an insulator.
The addition of parasitic elements gives a diminishing improvement in the antenna's gain. [2] Adding a reflector to a dipole, to make a 2 element Yagi, increases the gain by about 5 dB over the dipole. Adding a director to this, to give a 3 element Yagi, gives a gain of about 7 dB over a dipole.
A turnstile antenna, or crossed-dipole antenna, [1] is a radio antenna consisting of a set of two identical dipole antennas mounted at right angles to each other and fed in phase quadrature; the two currents applied to the dipoles are 90° out of phase. [2] [3] The name reflects the notion the antenna looks like a turnstile when mounted ...
The AN/FLR-9 is a type of very large circularly disposed antenna array, built at eight locations during the Cold War for HF/DF direction finding of high priority targets. The worldwide network, known collectively as "Iron Horse", could locate HF communications almost anywhere on Earth.
More common is electrical beam tilt, where the phasing between antenna elements is tweaked to make the signal go down (usually) in all directions. [1] This is extremely useful when the antenna is at a very high point, and the edge of the signal is likely to miss the target (broadcast audience, cellphone users, etc.) entirely.