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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.
A folded dipole is, technically, a folded full-wave loop antenna, where the loop has been bent at opposing ends and squashed into two parallel wires in a flat line. Although the broad bandwidth, high feedpoint impedance, and high efficiency are characteristics more similar to a full loop antenna, the folded dipole's radiation pattern is more ...
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal nĚ‚, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
The standard way to calculate the T-matrix is the null-field method, which relies on the Stratton–Chu equations. [6] They basically state that the electromagnetic fields outside a given volume can be expressed as integrals over the surface enclosing the volume involving only the tangential components of the fields on the surface.
The source free equations can be written by the action of the exterior derivative on this 2-form. But for the equations with source terms (Gauss's law and the Ampère-Maxwell equation), the Hodge dual of this 2-form is needed. The Hodge star operator takes a p-form to a (n − p)-form, where n is the number of dimensions.
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.
In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]
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 ...