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When so loaded the antenna presents a pure resistance to the transmission line, preventing energy from being reflected. The loading coil is often placed at the base of the antenna, between it and the transmission line (base loading), but for more efficient radiation, it is sometimes inserted near the midpoint of the antenna element (center ...
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.
An antenna such as the one described above is usable for both local and medium-long-distance communication across a frequency range of about 1:6 . For example, an antenna for the lower portion of shortwave (say, 3–18 MHz) will be roughly 33 m (110 feet) long, with conductors spaced 1 m (3.3 feet). For the higher portion of shortwave (5–30 ...
A competing third criterion is the number and bandwidth of the frequenc(y/ies) that a single antenna intercepts or emits. A fourth design goal is to make the antenna directional: To project or intercept radio waves from only one vertical and / or horizontal direction as exclusively as possible. Simple antennas
NEC is widely used for modeling antenna designs, particularly for common designs like television and radio antennas, shortwave and ham radio, and similar examples. Examples of practically any common antenna type can be found in NEC format on the internet.
The discone antenna has a useful frequency range of at least 10 to 1. [2] [3] When employed as a transmitting antenna, a properly constructed discone is just as efficient as an antenna designed for a more limited frequency range. The extra bandwidth comes from the controlled taper and large termination radius of the cone.
In this circumstance, a ‘T’-antenna is a capacitively top-loaded, electrically short, vertical monopole. [4]: 578–579 Despite its improvements over a short vertical, the typical ‘T’-antenna is still not as efficient as a full-height 1 / 4 λ [c] vertical monopole, [5] and has a higher Q and thus a narrower bandwidth.
The gain and input impedance of the antenna is dependent on the length of the whip element, compared to a wavelength, but also on the size and shape of the ground plane used (if any). A quarter wave vertical antenna working against a perfectly conducting, infinite ground will have a gain of 5.19 dBi and a radiation resistance of about 36.8 ohms.