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A 20-meter-long T²FD antenna, covering the 5-30 MHz band. The Tilted Terminated Folded Dipole (T²FD, T2FD, or TTFD) or Balanced Termination, Folded Dipole (BTFD) - also known as W3HH antenna - is a general-purpose shortwave antenna developed in the late 1940s by the United States Navy.
It is a two element Yagi-Uda antenna with folded dipole elements, and no director(s). Because of the folded ends, the element lengths are approximately 70% of the equivalent dipole length. The two-element design gives modest directivity (about 2.0 dB ) with a null towards the rear of the antenna, yielding a high front-to-back ratio : Gain up to ...
This shape-indifference allows otherwise prohibitively long dipoles to have their far ends bent sideways, folded over, or zig-zagged, in order to shorten the antenna to fit inside an available space. (The use of fold here is not the same as "fold" in "folded dipole" or "folded unipole".) This apparent mangling has very little affect on the ...
terminated coaxial cage monopole The TC²M is a vertical polarized broadband shortwave antenna. The antenna can be characterized by being a vertical traveling-wave coaxially caged monopole over a ground plane, or alternatively described as a folded unipole with a terminating resistor. [5] off-center fed dipole antennas
Curtain arrays were originally developed during the 1920s and 1930s when there was a lot of experimentation with long distance shortwave broadcasting. The underlying concept was to achieve improvements in gain and/or directionality over the simple dipole antenna, possibly by folding one or more dipoles into a smaller physical space, or to arrange multiple dipoles such that their radiation ...
A "folded dipole" type of halo, similar to the original halo patent. [1] Gain along Y axis 1.2 dBi, gain along Z axis −10 dBi, gain along X axis −1.7 dBi. Fed at the center of the bottom conductor (at the red mark; feed-line not shown), supported at the center of the top conductor which is at ground potential for RF.
When a well-made folded-unipole replaces a decrepit antenna, or one with a poor original design, there will of course be an improvement in performance; the sudden improvement may be cause for mistakenly inferred superiority in the design. Experiments show that folded-unipole performance is the same as other monopole designs: Direct comparisons ...
It consists of 175 folded dipole antennas. An early phased array , the antenna radiated a vertical fan-shaped beam which could be swept horizontally across the airspace in front of the antenna. An antenna array (or array antenna ) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves .