JPH05206719A - Helical antenna - Google Patents

Abstract

PURPOSE:To obtain the helical antenna whose feeding loss is small and whose distortion of directivity is small in which the structure is simple and which has immunity to vibration and shock and whose directivity and band width are broad. CONSTITUTION:A 1st hybrid H1 dividing a received high frequency signal into equally two signals whose phase differs from each other and 2nd and 3rd hybrids H2, H3 connecting to two output terminals of the 1st hybrid H1 via two connection lines whose length differs by 1/4 wavelength of the said high frequency signal are formed to a board 3. Furthermore, the 2nd and 3rd hybrids H2, H3 and matching circuits M1-M4 taking matching with an exciting impedance of the radiation element 11 provided a film element 11 are provided to a board 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical antenna used in a mobile station of a mobile satellite communication system.

[0002]

2. Description of the Related Art An antenna used for a mobile station of a mobile satellite communication system is required to have a wide directivity and a structure suitable for mounting on a mobile body.

The microstrip antenna has a wide directivity, can be easily miniaturized, and is strong against vibration and shock, and is suitable for this type of application. However, this microstrip antenna has the major drawback of having a narrow bandwidth. For this reason, a mobile station of a mobile satellite communication system has the advantages of wide directivity and wide bandwidth, and a BackfireQuadrifir Helical Antenna.
A helical antenna that is said to be used in some cases.

FIG. 5 shows the conventional backfire described above.
FIG. 6 is a perspective view showing an example of a quadratic helical antenna, and FIG. 6 is a block diagram thereof.

The reflector 20 is a disk-shaped member made of metal, and a tube 21 is erected on the reflector 20. Further, the input terminal I and the hybrid H4 are provided on the back surface of the reflection plate 20, and coaxial lines L7 and L8 are provided. Further, inside the pipe 21, the balun B1,
B2 is provided.

The cylindrical dielectric member 22 is supported by a support member led out from the tube 21, and the peripheral surface thereof has a diameter of 4 mm.
The two radiating elements 23 are spirally arranged.

Next, the operation of this backfire quadrifier helical antenna will be described.

The high frequency signal input to the input terminal I is generated by the hybrid H4 arranged on the back surface of the reflection plate 20.
It is divided into two high-frequency signals whose phases differ from each other by π / 2. The high frequency signals divided into two equal parts are respectively fed to the coaxial line L.
Balun B placed inside the pipe 21 through 7, L8
1, led to B2. The baluns B1 and B2 equally divide the input high frequency signal into two signals having mutually opposite phases, and excite two radiating elements 23 facing each other by these signals. As a result, circularly polarized waves are radiated from the radiating element 23 in a wide direction.

[0009]

However, in the above-mentioned conventional helical antenna, the dielectric member 22 is connected to the tube 21.
Since the baluns B1 and B2 are arranged inside the tube 21, the structure is complicated and it is weak against vibration and impact. In addition, since the distance from the input terminal I arranged on the back surface of the reflection plate 20 to the excitation point of each radiating element 23 located at the upper end of the dielectric member 22 is long, there is a drawback that the power feeding loss is large. Furthermore, baluns B1 and B2
Are three-dimensionally configured, and variations in impedance characteristics due to the formation error of each balun, and each radiating element 23.
Since the variation of the excitation amplitude and the excitation phase difference is large, there is also a drawback that the directional distortion is large.

The present invention has been made in view of the above problems, and has a simple structure, is resistant to vibration and shock, has a wide directivity and a wide bandwidth, and has a small power feeding loss and a small directivity distortion. The purpose is to provide a helical antenna.

[0011]

A helical antenna according to the present invention has four output terminals provided at positions of four equal points on the circumference of a predetermined circle by dividing a high frequency signal input from an input terminal into four equal parts. A power distributor having a planar structure for sequentially outputting π / 2 different phases, and spirally arranged on the peripheral surface of a cylindrical dielectric member aligned with the circumference of the predetermined circle. The end on the power distributor side has four radiating elements electrically connected to the four output ends of the power distributor.

[0012]

The helical antenna according to the present invention comprises a power distributor having a planar structure and four radiating elements spirally arranged on the peripheral surface of a cylindrical dielectric member. The ends on the side of the power distributor are connected to the output ends of the power distributors provided at predetermined positions. That is, the helical antenna according to the present invention does not have the tube for supporting the dielectric member and the balun arranged in this tube as in the conventional case, and therefore has a simple structure and is resistant to vibration and shock. Further, the power distributor and the radiating element can be connected in a short distance, and the power feeding loss can be reduced. Furthermore, the advantage of the helical antenna that the directivity and the bandwidth are wide is maintained.

The dielectric member and the radiating element can be easily manufactured, for example, by joining both ends of a dielectric sheet provided with a strip-shaped metal thin film to be the radiating element to form a cylindrical shape. However, since the strength of the dielectric member supporting the radiating element is insufficient as it is, the inside of the dielectric member is filled with the foaming resin. As a result, the weight of the dielectric member that supports the radiating element can be reduced and the strength can be improved.

In the power distributor, for example, a high frequency signal input from an input terminal is converted into two signals having mutually different phases.
It is composed of a first hybrid that is equally divided, and second and third hybrids that are connected to two output terminals of the first hybrid via connection lines. The connection line connecting the first hybrid and the second hybrid and the connection line connecting the first hybrid and the third hybrid differ by ¼ of the wavelength of the high frequency signal. .. By this, π / 2
Signals having different phases can be supplied to the four radiating elements, respectively.

In this case, a matching circuit having a planar structure is interposed between the second and third hybrids and the output end,
It is preferable to match the output impedance of the second and third hybrids with the excitation impedance of each radiating element.

[0016]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a side view showing a helical antenna according to an embodiment of the present invention, and FIG. 2 is a bottom view of the same.

On one surface side (lower surface side) of the mounting plate 1 made of metal, a dielectric plate 2, a substrate 3 and a restraining plate 4 are arranged in this order and screwed to the mounting plate 1. There is. On the other surface side of the mounting plate 1, a dielectric plate 9 and a substrate 10 are arranged in this order and screwed to the mounting plate 1.

FIG. 3 is a plan view showing the substrate 3. Board 3
Is composed of a dielectric plate 31 and metal thin films adhered to both surfaces of the dielectric plate 31, and the metal thin film on one surface (the surface on the side in contact with the dielectric plate 2) has a predetermined shape. Are etched (ie, the conductor pattern 32). The metal thin film on the other surface of the substrate 3 and the mounting plate 1 serve as an outer conductor, and the conductor pattern 32 serves as an inner conductor to form a stripline circuit.

The conductor pattern 32 includes the patterns of the hybrids H1, H2 and H3, the connection conductor L1 for connecting the hybrid H1 and the coaxial connector 5, and the connection between the hybrid H1 and the hybrids H2 and H3. Connection conductors L2, L3 and hybrids H1, H2
It is composed of connection conductors L4, L5, and L6 for connecting H3 and the terminating resistors 6, 7, and 8. Further, through holes TH1 to TH4 are provided at each two output ends of the hybrids H2 and H3. These through holes TH1 to TH4 are provided at positions that divide the circumference of a predetermined circle into four equal parts. Furthermore, the coaxial connector 5 of the connection conductor L1
A through hole TH5 is provided at the end portion on the side.

The coaxial connector 5 is screwed to the holding plate 4. The center conductor of the coaxial connector 5 is soldered to the connection conductor L1 through the through hole TH5. The non-grounded terminals of the terminating resistors 6, 7 and 8 are soldered to the ends of the connection conductors L4, L5 and L6, respectively. The ground side terminals of these terminating resistors 6, 7 and 8 are screwed to the mounting plate 1.

Like the substrate 3, the substrate 10 is also composed of a dielectric plate and metal thin films deposited on both surfaces of the dielectric plate, and the metal thin film on the surface in contact with the dielectric plate 9 is etched. Is patterned as a conductor pattern of the matching circuits M1 to M4. These matching circuits M1 to M4
Are all stripline stubs with open ends. The conductor patterns, which are the inner conductors of these stripline stubs, have through holes TH1 to TH4 of the substrate 3.
Are connected to the respective through holes provided on the substrate 10 so as to be concentric with. Then, metal pins 15 are inserted into these through holes, and these pins 15 are led out on the substrate 10.

The film element 11 comprises a cylindrical dielectric film and four radiating elements 111 spirally formed on the outer peripheral surface of the dielectric film at equal intervals. The film element 11 is formed into a cylindrical shape by adhering a dielectric sheet having a metal thin film etched into a predetermined shape on one surface thereof at an adhesion margin 112. The outer diameter of the film element 11 is set so as to match the diameter of the circle circumscribing the through holes TH1 to TH4 of the substrate 3. In addition, the film element 11 includes the mounting plate 1
It is arranged with the rod 12 screwed to the central axis as
It is held down and fixed by the lid 14 attached to the distal end of the No. 2. The ends of the radiating elements 111 are electrically connected to the matching circuits M1 to M4 via the pins 15, respectively. Furthermore, in order to increase the rigidity of the film element 11, the foamable resin 1 is provided inside the film element 11.
3 is filled.

Next, the operation of the helical antenna according to this embodiment will be described with reference to the block diagram shown in FIG.

The high frequency signal input to the coaxial connector 5 is equally divided into two high frequency signals having different phases by the hybrid H1. Hybrid H1 to connection conductor L
The phase of the high frequency signal output to 2 is the hybrid H1
From the phase of the high-frequency signal output to the connecting conductor L3 by π / 2. Since the length of the connection conductor L2 is shorter than the length of the connection conductor L3 by ¼ of the wavelength of the high frequency signal, the phase of the high frequency signal input to the hybrid H2 through the connection conductor L2 passes through the connection conductor L3. The phase of the high frequency signal input to the hybrid H3 advances by π. The high-frequency signals input to the hybrids H2 and H3 are two high-frequency signals whose mutual phase difference is π / 2.
Through hole TH1, TH2, TH3, TH
4 is output. These through holes TH1, TH
The amplitudes of the high frequency signals output to 2, 2, TH3 and TH4 are equal to each other, and the phases are sequentially delayed by π / 2 in this order.
Each of these high frequency signals excites each radiating element 111 via each pin 15.

For the convenience of design, the hybrid H1 to
Each H3 is designed to have an input / output impedance of 50Ω. On the other hand, since the excitation impedance of the radiating element 111 is different from 50Ω, the hybrid circuits H2 and H2 are matched by the matching circuits M1 to M4 including stripline stubs.
Impedance matching between each output terminal of H3 and each radiating element 111 is performed.

4 which are rotationally symmetrically arranged at 90 ° intervals from each other
Since the one spiral radiating element 111 is excited by a high-frequency signal of equal amplitude whose phase is sequentially different by π / 2 along a predetermined rotation direction, circularly polarized waves are radiated in space.

In the above description, the case where the antenna is used as the transmitting antenna is described, but when the antenna is used as the receiving antenna, the present embodiment receives circularly polarized waves and outputs them from the coaxial connector 5.

The helical antenna according to this embodiment has an advantage common to helical antennas in that both directivity and bandwidth are wide. Further, the helical antenna according to the present embodiment has impedance characteristics of hybrid H1 to H1.
It is determined by the impedance characteristics of H3 and the matching circuits M1 to M4, and these impedance characteristics are mainly determined by the formation error of the conductor pattern of the substrates 3 and 10. Since the formation error of the substrates 3 and 10 can be easily reduced, the impedance characteristic can be easily improved. Further, since each output end of the hybrids H2 and H3 and each radiating element 111 are connected by the pin 15 in a very short distance, the power feeding loss is extremely small. Further, the variations in the excitation amplitude ratio and the excitation phase difference of each radiating element 111 are mainly determined by the formation error of the conductor pattern of the substrates 3 and 10. Therefore, these formation errors are reduced to reduce the variations in the excitation amplitude ratio and the excitation phase difference. It is possible to easily reduce the distortion and the directional distortion.

[0030]

As described above, the helical antenna according to the present invention includes a power distributor having a planar structure that divides a high frequency signal into four equal parts, and a cylindrical dielectric body connected to the four output terminals of the power distributor. Since the radiating element is provided with four radiating elements spirally arranged on the peripheral surface of the member, and the radiating element can be supported with high rigidity by a simple structure, it is resistant to vibration and shock. Further, the helical antenna according to the present invention can shorten the distance from the output end of the power distributor to the excitation point of each radiating element, and since this power distributor has a planar structure and good impedance characteristics, it reduces power feeding loss. it can.
Furthermore, since the power distributor having a planar structure can accurately control the power division ratio and the phase difference between the divided powers, it is possible to suppress directivity distortion. Furthermore, if a matching element is provided at the connection point between the power distributor and each radiating element, good impedance characteristics can be obtained in a wide frequency range, and the effect of reducing matching loss can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing a helical antenna according to an embodiment of the present invention.

FIG. 2 is a bottom view of the same.

FIG. 3 is a plan view showing the same substrate.

FIG. 4 is a block diagram of the same.

FIG. 5 is a perspective view showing an example of a conventional backfire quadrifier helical antenna.

FIG. 6 is a block diagram of the same.

[Explanation of symbols]

 1; Mounting plate 2, 9, 31; Dielectric plate 3, 10; Substrate 4; Suppression plate 5; Coaxial connector 6, 7, 8; Termination resistor 11; Film element 22; Dielectric member 23, 111; Radiating element

Front Page Continuation (72) Inventor Hiromasa Kato 3-50-1, Kamiishihara, Chofu City, Tokyo Anten Co., Ltd. (72) Inventor Kazuo Sekiya 3-50-1, Ueishihara, Chofu City, Tokyo Anten Co., Ltd.

Claims (4)

[Claims] 1. A plane that divides a high frequency signal input from an input terminal into four equal parts and outputs them to four output terminals provided at positions of four equal parts of the circumference of a predetermined circle in order of sequentially different phases by π / 2. The power distributor having a structure and a cylindrical dielectric member arranged in alignment with the circumference of the predetermined circle are spirally arranged on the peripheral surface of the power distributor, and the end on the power distributor side is the power distributor. Antenna having four radiating elements electrically connected to four output terminals of the container, respectively. 2. The dielectric member and the radiating element are formed by laminating both ends of a dielectric sheet provided with four strip-shaped metal thin films arranged in parallel with each other. The helical antenna according to claim 1, wherein a foaming resin is filled inside the body member. 3. The power distributor divides a high frequency signal input from the input terminal into two signals having mutually different phases.
A first hybrid that divides into equal parts and two output terminals of the first hybrid have a length of 1 / wavelength of the high frequency signal.
The helical antenna according to claim 1 or 2, wherein the helical antenna is composed of a second hybrid and a third hybrid that are respectively connected via two connection lines that differ by four. 4. The helical antenna according to claim 3, wherein a matching circuit having a planar structure is interposed between the second and third hybrids and the output end.