JP2549240Y2 - 4-segment helical antenna with lightning rod - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a countermeasure against lightning strikes of a four-segment helical antenna mounted on an aircraft, and relates to a four-segment helical antenna device capable of effectively obtaining a lightning arrester without disturbing the radiation pattern of the antenna. .

[0002]

2. Description of the Related Art As an antenna used in a communication system using a geostationary satellite or an orbiting satellite, etc., a four-segment helical antenna has been attracting attention and has been widely used as an antenna for mounting on an aircraft or a land mobile vehicle. .

FIG. 2 is a sectional view showing an example of a conventional four-segment helical antenna used in such a system.

The four-segment helical antenna shown in FIG. 1 is arranged in a radome 102 attached to a base 101, and a balun 103 attached on the base 101.
And an antenna body 10 provided on the balun 103.
4 and the balun 10 provided below the base 101.
3 is connected to the hybrid circuit (HYB) 105.

As shown in FIG. 3, the antenna body has an insulating member 106 such as a mylar member (hereinafter, referred to as a mylar member) formed in a cylindrical shape, and two sets of antennas spirally wound around the outer periphery of the mylar member 106. Element 107, 1
08, and each of these antenna elements 10
7 and 108 are connected to four terminals of the balun 103, respectively.

[0008] The balun 103 is connected to the hybrid circuit 10.
5 is a portion for adjusting the balance / unbalance between the antenna element 107 and each of the antenna elements 107 and 108.
01 is connected to the hybrid circuit 105 through a coaxial cable or the like.

The hybrid circuit 105 converts a signal output from a transmitter disposed in an aircraft or the like into two signals whose phases are shifted from each other by a predetermined angle and supplies the two signals to the antenna via the balun 103. A process of combining two received signals which arrive at the main body and are output via the balun 103 and shifted by a predetermined angular phase, and supply the combined signals to the receiver.

However, in the four-segment helical antenna described above, a high voltage current due to lightning strikes easily enters a hybrid circuit, a phase shifter or a transceiver (not shown), and the high voltage current is generated by these components. Breaking into the hotline of equipment can lead to destruction.

From such a point, the conventional radome 10
2 Conductor line or conductor band 110 such as copper wire or copper foil along the inner wall
Was wired, and the lower end of the fuselage was grounded to obtain a lightning arrester effect.However, when a conductor was placed close to an omnidirectional antenna such as a four-segment helical antenna,
There is a problem that the radiation pattern is disturbed.

FIG. 4 shows a conventional LIGHTNIN.
FIG. 4 is a cross-sectional view of a lightning arrester called G PROTECTION, in which conductive particles 111 sufficiently small in comparison with the wavelength of a radio wave radiated from an antenna are buried within the thickness of the radome 102 at a small interval, thereby obtaining conductive particles. This LIGHTNING is to secure the ground to the aircraft through the stray capacitance between them.
PROTECTION has a problem that although the conductive particles 111 are very small in comparison with the wavelength of the radio wave, the adverse effect on the radiation pattern of the antenna is relatively small, but it is expensive because it requires extremely fine processing.

[0011]

The object of the present invention is to realize effective lightning arresters by eliminating the disturbance of the radiation pattern and the increase in cost, which have been problems in the above-mentioned conventional lightning strike countermeasures for a four-segment helical antenna. It is an object of the present invention to provide a four-segment helical antenna with a lightning rod.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a four-segment helical antenna having an antenna body that is erected on a mounting surface of the antenna via a balun for adjusting balance / unbalance. The antenna body includes a cylindrical mylar member, and at least four band-shaped antenna elements spirally wound around the outer peripheral surface of the mylar member, and the upper end of each antenna element is led out to the upper end surface of the mylar member. The upper ends of the antenna elements are electrically connected to each other, the lower ends of the antenna elements are grounded to the antenna mounting surface before the balun, and the upper ends of the antenna elements located at the tops of the mylar members. And a lightning rod is erected on the upper end surface of the antenna body and connected to the upper end of the antenna element. It is intended.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIGS. 1 (a) and 1 (b) are a schematic perspective view and a perspective view, respectively, showing a first embodiment of a four-segment winding helical antenna according to the present invention.

The four-segment helical antenna 1 includes a base 2 fixed on a body (antenna mounting surface) of an aircraft or the like.
A case 3 containing a hybrid circuit and an antenna main body 6 are erected through a balun 5 on the top, and project upward from the top of the antenna main body 6, and the tip of the antenna 3 extends from the top of the radome 7 to the outside. And a conductor lightning rod (lightning rod) 8 arranged to protrude. The antenna body 1 includes a mylar member 10 formed of a resin or the like in a cylindrical shape as described with reference to FIG. 3, and four antenna elements 11 spirally wound around the outer periphery of the mylar member 10. The respective lower ends of the antenna elements 11 are connected to four terminals of the balun 5.

In practice, the connection between each lower end of each of the antenna elements 11 and the four terminals of the balun 5 is made by connecting the lower end of the four-segment helical antenna, which is a balanced line, to two unbalanced coaxial cables. This is for matching and is connected as shown in FIG.
Is grounded with respect to the body in terms of direct current, so that the lightning rod 8 is grounded. Note that the upper end surface of the antenna main body to which the lightning rod 8 is joined (mylar member 10)
A pattern 13 which is the upper end of the antenna element 11 is located at the top of the antenna element 11.
3 is connected. The pattern 13 is a portion where the current distribution is zero.

The hybrid circuit in Case 3 derives two signals whose phases are shifted from each other by a predetermined angle with respect to signals input / output from a transmitter / receiver arranged in the aircraft, and supplies the signals to the balun 5; A process of combining two received signals received by the main body and output via the balun 5 and supplying the combined signals to the transceiver. The case 3 may be arranged below the base, that is, inside the body.

The upper ends of the four antenna elements 11 extend on the upper end surface of the antenna main body 6, and electrically connect a pair of the four ends facing each other. In this embodiment, a pair of opposite ends are connected as an extension of the antenna pattern, while the other pair of ends are connected by a wire 12. Since the lightning rod 8 is erected on the top pattern 13 by welding or the like and the upper part thereof is supported and fixed by the radome 7, sufficient mechanical strength can be secured.

Since the current distribution is zero at the pattern 13 located at the top of the mylar member 10, even if the lightning rod 8 is erected on this portion, the characteristics of the antenna are not significantly affected, In the case of application to an application where even an insignificant effect cannot be neglected, the necessary adjustments to the antenna element length and the components such as the balun 5 are made so that a desired radiation pattern can be obtained in consideration of the effect of the lightning rod in advance. You only need to give it.

In the above configuration, during the operation of the aircraft,
If a lightning strike occurs on the shunt wound helical antenna 1, the lower part of the antenna element is DC-grounded to the body (ground) in front of the balun. It is possible to avoid a situation in which a hybrid circuit or the like is broken by entering the hot line from the element.

Further, since the lightning rod 8 is supported by the radome, sufficient mechanical strength can be secured.
In addition, the number of parts and the number of assembling steps are not significantly increased, which is advantageous in cost.

[0022]

[Effects of the Invention] As described above, according to the present invention, it is possible to realize effective lightning arresters by eliminating the disturbance of the radiation pattern and the cost increase, which have been a problem in the lightning strike countermeasures of a four-wire helical antenna. Can be.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a perspective external view and a main part perspective view showing a first embodiment of a four-segment winding helical antenna according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional four-segment helical antenna.

FIG. 3 is a diagram illustrating the configuration of a conventional 4-segment helical antenna.

FIG. 4 is a sectional view showing a conventional lightning arrester structure.

[Explanation of symbols]

1 ... 4 line segment helical antenna, 2 ... base,
3 case, 6 antenna body, 7 radome, 8 lightning rod (lightning rod), 10 mylar member, 11 antenna element,

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-74906 (JP, A) JP-A-3-3822 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A 4 line number helical antenna with an antenna body to be erected via the balun for balanced / unbalanced adjusted on the antenna mounting surface, the antenna body is a cylindrical mylar member, the At least four strip-shaped antenna elements spirally wound on the outer peripheral surface of the mylar member. The upper ends of the antenna elements are respectively led out to the upper end surface of the mylar member and electrically connected to each other. And the lower end of each antenna element is grounded to the antenna mounting surface in front of the balun, and positioned at the top of the mylar member.
Current distribution at the upper end of the antenna element
And the upper end of the antenna body
A lightning rod is erected and connected to the upper end of the antenna element.
A four-segment helical antenna provided with a lightning rod.