half-wave dipole

half-wave dipole

See dipole.

Half-Wave Dipole

 

a radiator of electromagnetic waves that consists of a straight thin conductor or of a slot in the metal wall of a wave guide. The length of the conductor or slot is equal to approximately half the radiator’s operating wavelength. Half-wave dipoles are used, for example, as simple antennas for radio communication and as receiving antennas for television (Figure 1). They are also used as radiating elements of antenna arrays in communication and radar systems.

To the gap in the center of the dipole there is connected a feeder, or transmission line, which is either a balanced line or an unbalanced line with a balancing unit. The feeder connects the

Figure 1. Simple television antenna: (1) half-wave dipole, (2) feeder, (3) support, (λ) operating wavelength; the broken line shows the distribution of the current / along the dipole

dipole to the transmitter or receiver. The radiation pattern of a half-wave dipole is a circle in a plane perpendicular to the axis of the dipole and a symmetrical figure eight in a plane containing the axis. The front-to-rear ratio of a half -wave dipole is 1.64. The radiation resistance is ~ 73 ohms.

half-wave dipole

[′haf ¦wāv ′dī‚pōl]
(electromagnetism)
References in periodicals archive ?
Since the wire antenna is similar to a half-wave dipole and the cable in a typical setup usually much longer than the board size, the effective length of the wire antenna can be approximated as the cable length, [l.
Two half-wave dipole antennas 900 MHz and 1800 MHz were used as the exposure sources for this study.
Each of them can be simply model by a half-wave dipole connected to the different positions in feed line.
The first example considers a half-wave dipole placed directly on the lossy ground, Fig.
The large effect of directivity is easily seen when comparing a horn antenna with as much as 30- dBi gain--dBi means dB relative to isotropic--and a much less directional half-wave dipole with 2.
A half-wave dipole antenna is used as a standard of comparison.
The multi-band bridge is enclosed in an aluminum housing and includes two half-wave dipole antennas.
A standard half-wave dipole antenna was used as the exposure source for this study.
In formula (2), the dipole element can be equivalent to a half-wave dipole and the array-element function can take cos[([pi]/2) sin[delta]]/cos[delta].
The capacitively-loaded structure makes the antenna have a smaller size in comparison with the conventional half-wave dipole antennas at a given operating frequency.
A half-wave dipole one-quarter wavelength above a ground plane has an effective area of 0.
Early research during World War II determined the ideal form for a radar reflective countermeasure material should be a thin filament cut in length at just under half the wavelength of the radar to be countered, now known as a half-wave dipole.