Search results
Results from the WOW.Com Content Network
Neglecting electrical inefficiency, the antenna gain is equal to the directive gain, which is 1.50 (1.76 dBi or -0.39 dBd) for a short dipole, increasing to 1.64 (2.15 dBi or 0 dBd) for a half-wave dipole. For a 5 / 4 wave dipole the gain further increases to about 5.2 dBi, making this length desirable for that reason even though the ...
A halo antenna, or halo, is a center-fed 1 / 2 wavelength dipole antenna, which has been bent into a circle, with a break directly opposite the feed point. The dipole's ends are close, but do not touch, and the ends on either side of the gap may be flared out to form a larger air gap capacitor , whose spacing is used to fine-adjust the ...
Since all of the equivalent dipole's radiation is concentrated in a half-space, the antenna has twice the gain (+3 dB) of a similar dipole, neglecting power lost in the ground plane. [2] Quarter-wave monopole The most common monopole is a vertical, 1 / 4 wave tall, which is the minimum size for it to self-resonate.
The electric field strength at a specific point can be determined from the power delivered to the transmitting antenna, its geometry and radiation resistance. Consider the case of a center-fed half-wave dipole antenna in free space, where the total length L is equal to one half wavelength (λ/2). If constructed from thin conductors, the current ...
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. As a rule of thumb, each additional parasitic element beyond this adds about 1 dB of gain. [2]
The ordinary half-wave dipole is probably the most widely used antenna design. This consists of two 1 / 4 wavelength elements arranged end-to-end, and lying along essentially the same axis (or collinear), each feeding one side of a two-conductor transmission wire. The physical arrangement of the two elements places them 180 degrees out ...
[1] [2] [3] Particularly in the fields of fiber optics, lasers, and integrated optics, the term radiation pattern may also be used as a synonym for the near-field pattern or Fresnel pattern. [4] This refers to the positional dependence of the electromagnetic field in the near field, or Fresnel region of the source. The near-field pattern is ...
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 ...