JP3334134B2 - Helical antenna system - Google Patents

Description

The present invention relates to an antenna system having a helical feeder.

A helical feed antenna includes a single conductor or a multi-wire conductor provided in a helical configuration. Compared to some other possible modes, helical antennas are usually used in so-called axial or normal modes. The axial mode provides maximum radiation along the ihelical axis that occurs when the helix circumference is at a value of one wavelength. Normal mode results in radiation directed toward the helix axis, which occurs when the helix diameter is small relative to wavelength. The axis mode is of special interest in the proposal according to the invention.

The use of helical antennas in antenna systems is widely known. For example, U.S. Pat.
No. 747 discloses a coaxial-fed helical antenna with a feeder board providing endfire radiation towards the disk and a director board between the helical. In this US patent, the helix size in such an antenna system is given.

U.S. Pat. No. 4,742,359 discloses an antenna system using a helical antenna having two ends with a first end connected to a feed line. The purpose of the following description is to make it possible to understand that the feed lines are connected in a row to the axis of the helical antenna. Such a helical antenna is assembled as a so-called end-fire helical antenna and flows under the maximum received power conditions at the first end, where the direction of the signal power is in the same direction as the received radiation. Also, such helical antennas are assembled as so-called backfire helical antennas, which flow under the maximum received power conditions to the first end, where the direction of the signal power is opposite to the direction of the received radiation. In said U.S. patent, an antenna system consisting of a reflector, a main helical antenna having a coil with a pair of ends is proposed. The coil is located at the focal point of the reflector. Since the axis of the helical antenna essentially coincides with the axis of the reflector. A feed line is connected to the antenna system with the external circuit. Because the main helical antenna is a backfire helical antenna coupled to the feed line at the end near the reflector, and the other end of the helical antenna is a free end, and This is because the power supply line is a coaxial cable.

Furthermore, the use of one or more helical antennas with a dielectric lens is also known from international application WO 92/13373. Signals from several directions can be received simultaneously.

In the axial mode, a helix provided in a clockwise helix receives a clockwise rotation of polarization, while a helix provided in a counterclockwise helix receives a counterclockwise rotation of polarization.

If both polarization directions were received at the same time, at least two helices would be needed. If these helicals are a set of antenna systems using focusing means, it is important that two feeders be simultaneously at the focus of the focusing means. The unacceptable loss drop is complicated for at least one polarization direction. Furthermore, if they are placed as close together as possible, the necessary defocusing and / or crosstalk caused by strong coupling between the helices will result.

It is an object of the present invention to provide an antenna system having a focusing means and a helical feeder in which at least two different circularly polarized radiations can be received simultaneously without loss loss compared to known systems.

In the present invention, there is not one helical feeder provided in each polarization direction but two or more. These helical feeders preferably operate in an axial backfire mode.

 The following considerations are in accordance with the principles of the present invention.

As a means for focusing, for example, a parabolic reflector, a dielectric lens, a Luneberg-type lens, or the like, is a focal point for focusing incident radiation. If 2
When radiation with two opposite polarizations is received, two helical feeds must be provided near the focal point. The implication is that the two helices cannot be co-located at the focal point. Two or more helices in each polarization direction provided according to the invention were provided to compensate for the loss drop.

Further, features, effects and detailed description of the present invention will be made in the following embodiments based on the drawings.

 FIG. 1 is a side view of the preferred embodiment.

 FIG. 2 is a front view of the preferred embodiment.

 FIG. 3 shows a preferred embodiment of the power combiner.

In FIG. 1, a parabolic reflector 10 functions as a focusing means and has a reflector axis 10a and a focal point 11. This focus 1
Around 1 are two helical feeders 12a, having the same winding direction and receiving the main radiation with the same annular polarization.
There is 12b. Each of the helical feeders 12 has a respective director board 13a, 13b. The signal received by the feeder 12 is contained within a housing 15 and is mounted on a circuit board (not shown in FIG. 1), which includes a coaxial cable, a semi-rigid cable, or the like, respectively, a feeder line 14a, Guided through 14b. Furthermore, there is a second set of helical feeders 22a, 22b configured in the opposite winding direction as compared to feeder 12. These feeders 22 are not shown in FIG. 1 but are shown in FIG. 2 which shows a front view of this embodiment. Each of the feeders 22 has a respective director board 23a, 23b.

The diameter d1 of the waveguide boards 13 and 23 is about 0.25 × La, and this L
a is the wavelength of the received radiation. In a preferred embodiment, the diameter d2 of the helical 12,22 is about 0.3 × La. The length d3 between the centers of the same pair of two helicals 12a, 12b or 22a, 22b is about 0.7 × La.

In the present embodiment, the housing 15 has a shape like a tube based on an annular shape having a diameter d4 of about 0.8 × La.

Focus 11 on each set of helical 12 or 22
It is relatively arranged between the two. Line segment FF 'or f
Each center of −f ′ coincides with the focal point 11 of the focusing means 10.

The input power in each direction of the polarization is
Is added inside. A preferred embodiment of such a power combiner is shown in FIG. 3 for one waveguide direction. The inner conductor of the feed line 14 has microstrip lines 16a, 16b, respectively, having a common coupling point 17. Output line 18 leads to the next stage (not shown) of the low noise converter (LNC).
If the received signal is a television broadcast signal, the information in the signal can be displayed by the television.

In other waveguide directions, other power combiners are provided of the same type as shown in FIG.

To process the signals received by the feeders 12, 22, two LNC circuit boards may be provided orthogonal to each other. Since they are assembled into crossing, "T" or similar shapes, they are housed in a housing 15 which is shaped like a tube based on a cylinder, triangle, square, or the like.

The variant of this embodiment includes at least one of the following modifications.

-It is possible to provide more than one helical feeder for reception in each waveguide direction. In such a case, the phase centers F, f are assembled into a triangle, a quadrangle, or the like.
The helical feeder is preferably arranged such that the center of a triangle, square or similar shape coincides with the focal point 11.

-Instead of the reflector 10, any other focusing means can use reflection, refraction and / or diffraction functions.
Other preferred focusing means are Luneberg-type lenses which are spherical, hemispherical, quadrant or similar.

-By connecting the second set (22) of helical feeders to the first set (12) of helical feeders, a linear guided signal may be received. The linear waveguide direction can be selected by the phase shift means.

The antenna system can be used to receive broadcast signals, similar television signals, audio broadcast signals or the like, which can be transmitted directly or indirectly from satellites; Also, the antenna system can be used for the reception of any other radio frequency signal with different waveguides.

Continuation of front page (56) References JP-A-4-200104 (JP, A) JP-A-3-141707 (JP, A) JP-A-56-93402 (JP, A) JP-A-60-191502 (JP) JP-A-5-191142 (JP, A) JP-A-60-210012 (JP, A) JP-A-63-172502 (JP, A) JP-A-54-38745 (JP, A) 5-191139 (JP, A) Japanese Utility Model 57-1912 (JP, U) Japanese Patent Publication No. 39-15157 (JP, B1) Japanese Patent Publication No. 4-502697 (JP, A) International Publication 92/13373 (WO, A1) US Patent 3,487,413 (US, A) US Patent 3,184,747 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 19/17 H01Q 11/08 H01Q 21/24

Claims (2)

(57) [Claims] 1. An antenna system having a helical feed (11) and a focusing means (10) driven in an axial backfire mode, wherein a first group of two or more helical feeds (12) is a first group. A second group of two or more helical feeders (22) provided for reception in the guided direction and provided for reception in the second guided direction; 22) A helical antenna system wherein the center point of the phase center (F; f) of each group coincides with the focal point (11) of the focusing means (10). 2. The antenna system according to claim 1, wherein a circuit board is provided for processing each of the received waveguide signals, and the circuit boards are orthogonal to each other.