Compact helical antenna with a sinusoidal profile modulating a fractal pattern
The invention concerns a helical antenna comprising a shape of revolution and a plurality of radiating strands helically wound around the shape of revolution, characterized in that each radiating strand is defined by a repetition of a fractal pattern comprising segments formed by a sinusoidal curve.
1. A helical type antenna having a rotational shape and a plurality of radiating strands coiled in a helix around the rotational shape, wherein each radiating strand is defined by a repetition of a fractal pattern comprising a sequence of segments, a sinusoidal curve having been applied on each segment of the sequence of the fractal pattern, so that each segment of each radiating strand corresponds to a half-period of a sinusoidal curve having a direction defined by the corresponding segment of the fractal pattern.
2. The helical type antenna according to claim 1 , wherein each segment corresponds to a half-period of a sinusoidal curve defined by
y
(
x
)
=
S
·
k
·
L
′
·
sin
(
π
L
′
·
x
)
,
where: S is an integer with a value within {−1; +1}, k is the ratio of the amplitude of the sinusoid and its half-wavelength, L′ is the horizontal width of the pattern.
3. The helical type antenna according to claim 1 , wherein each segment of the fractal pattern has an identical length.
4. The helical type antenna according claim 1 , wherein the fractal is of the von Koch type, each straight line whereof being replaced by a sinusoidal segment.
5. The antenna according claim 1 , wherein each of the radiating strands consist of a specified metal-clad zone, coiled in a helix on the lateral surface of a sleeve, such that the director axis of each strand is separated from the axis of the following strand by a specified distance, defined along any perpendicular to any director line of the sleeve as the distance between two points, each defined by an intersection between the axis of a strand and a perpendicular to any director line of the sleeve.
6. The antenna according to claim 1 , wherein the rotational shape is cylindrical or conical.
7. The antenna according to claim 1 , wherein the antenna includes four identical radiating strands.