JP2806670B2 - Helical antenna - Google Patents

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.

[0003] The microstrip antenna has advantages that it has a wide directivity, is easy to miniaturize, and is resistant to vibration and shock, and is suitable for this type of application. However, this microstrip antenna has a major drawback of narrow bandwidth. For this reason, a mobile station of a mobile satellite communication system is provided with a backfire / quadrature helical antenna having advantages of a wide directivity and a wide bandwidth.
A helical antenna is sometimes used.

FIG. 5 shows the above-described conventional backfire system.
FIG. 6 is a perspective view showing an example of a quadrifilar helical antenna, and FIG.

The reflection plate 20 is a disk-shaped member made of metal, and a tube 21 is erected on the reflection plate 20. 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, a balun B1,
B2 is provided.

A cylindrical dielectric member 22 is supported by a support member led out of a tube 21 and has a peripheral surface on which a dielectric member 4 is formed.
Two radiating elements 23 are spirally arranged.

Next, the operation of the backfire / quadrature helical antenna will be described.

The high-frequency signal input to the input terminal I is transmitted by the hybrid H4 disposed on the back surface of the reflection plate 20.
The signal is divided into two high-frequency signals having phases different from each other by π / 2. Each of the two high-frequency signals is divided into coaxial lines L
7, a balun B disposed inside the pipe 21 via L8
1, B2. The baluns B1 and B2 divide the input high-frequency signal into two signals having phases opposite to each other, and excite the two radiating elements 23 facing each other with 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, there are drawbacks in that the structure is complicated and the tube is susceptible to vibration and impact. Further, since the distance from the input terminal I provided 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 also a disadvantage that power supply loss is large. Furthermore, baluns B1, B2
Are formed in a three-dimensional manner, and variations in impedance characteristics due to the formation error of each balun,
Since the dispersion of the excitation amplitude and the excitation phase difference is large, there is also a disadvantage that the directivity is greatly distorted.

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 bandwidth, has a small power supply loss, and has a small distortion of directivity. It is an object to provide a helical antenna.

[0011]

A helical antenna according to the present invention has four output terminals provided at four quadrants of a predetermined circle by dividing a high-frequency signal input from an input terminal into four equal parts. And a power distributor having a planar structure that sequentially outputs a phase different by π / 2 from each other, and spirally disposed on a peripheral surface of a cylindrical dielectric member arranged in alignment with the circumference of the predetermined circle. have a four radiating elements ends of the power divider terminal connected respectively electrically to the four output terminals of the power divider, wherein
The power distributor consists of a metal mounting plate and the front and back of this mounting plate.
A pair of dielectric plates superposed on the surface and the outside of each dielectric plate
A pair of superimposed substrates, said substrates being dielectric
A metal thin film is applied to both sides of the plate,
The metal thin film on the side is a conductor forming a strip line circuit.
It is characterized by being formed into a body pattern .

[0012]

The helical antenna according to the present invention comprises a power distributor having a planar structure and four radiating elements spirally disposed on the peripheral surface of a cylindrical dielectric member. Are connected to the output terminals of the power distributors provided at predetermined positions, respectively. In other words, the helical antenna according to the present invention does not have a tube for supporting the dielectric member and a balun disposed in the tube unlike the related art, and therefore has a simple structure and is resistant to vibration and impact. Further, the power distributor and the radiating element can be connected to each other at a short distance, and the power supply loss can be reduced. Further, the advantages of the helical antenna, such as directivity and wide bandwidth, are 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 serving as a radiating element to form a cylindrical shape. However, since the strength of the dielectric member supporting the radiating element is insufficient if this state is maintained, the foamable resin is filled inside the dielectric member. Thereby, the weight of the dielectric member supporting the radiating element can be reduced, and the strength can be improved.

The power splitter converts a high-frequency signal input from, for example, an input terminal into two signals having mutually different phases.
The first hybrid is divided into equal parts, and the second and third hybrids are connected to two output terminals of the first hybrid via connection lines. The connection line connecting the first hybrid and the second hybrid differs from the connection line connecting the first hybrid and the third hybrid by １ ／ of the wavelength of the high-frequency signal. . As a result, π / 2
Only signals having phases different from each other can be supplied to the four radiating elements.

In this case, a planar matching circuit 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]

Next, an embodiment of the present invention will 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 thereof.

On one surface side (lower surface side) of the metal mounting plate 1, a dielectric plate 2, a substrate 3 and a holding plate 4 are arranged in this order, and are screwed to the mounting plate 1. I have. A dielectric plate 9 and a substrate 10 are arranged on the other surface of the mounting plate 1 in this order, and are screwed to the mounting plate 1.

FIG. 3 is a plan view showing the substrate 3. Substrate 3
Is composed of a dielectric plate 31 and a metal thin film adhered to both surfaces of the dielectric plate 31. The metal thin film on one surface (the surface in contact with the dielectric plate 2) has a predetermined shape. (That is, 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, thereby forming a strip line circuit.

The conductor pattern 32 includes a pattern of the hybrids H1, H2, and H3, a connection conductor L1 for connecting the hybrid H1 and the coaxial connector 5, and a connection conductor L1 for connecting 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, L6 for connecting H3 to the terminating resistors 6, 7, 8. The two output terminals of the hybrids H2 and H3 are provided with through holes TH1 to TH4. 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 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 via the through hole TH5. The non-ground terminals of the terminating resistors 6, 7, 8 are soldered to the ends of the connection conductors L4, L5, L6, respectively. The ground terminals of the terminating resistors 6, 7, 8 are screwed to the mounting plate 1.

Similarly to the substrate 3, the substrate 10 is composed of a dielectric plate and a metal thin film adhered to both sides of the dielectric plate. The metal thin film on the surface in contact with the dielectric plate 9 is etched. Are patterned as conductor patterns of the matching circuits M1 to M4. These matching circuits M1 to M4
Are strip line stubs each having an open end. Each conductor pattern, which is an inner conductor of these strip line stubs, is formed in the through holes TH1 to TH4 of the substrate 3.
Are connected to the respective through-holes provided in the substrate 10 so as to be concentric. Metal pins 15 are inserted into these through holes, and these pins 15 are led out onto the substrate 10.

The film element 11 is composed of a cylindrical dielectric film and four radiating elements 111 spirally formed at equal intervals on the outer peripheral surface of the dielectric film. The film element 11 is formed by bonding a dielectric sheet having a metal thin film etched into a predetermined shape on one surface thereof at a bonding margin 112 to form a cylindrical shape. The outer diameter of the film element 11 is set to match the diameter of a circle circumscribing the through holes TH1 to TH4 of the substrate 3. The film element 11 is mounted on the mounting plate 1.
The rod 12 is arranged with the rod 12 screwed to
2 and is held down and fixed by the lid 14 attached to the tip end. The ends of the radiating elements 111 are electrically connected to the matching circuits M1 to M4 via the pins 15, respectively. Further, inside the film element 11, foamable resin 1 is added to increase the rigidity of the film element 11.
3 are 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 split into two high-frequency signals having different phases by the hybrid H1. Connection conductor L from hybrid H1
The phase of the high-frequency signal output to the hybrid H2 is
Is advanced by π / 2 as compared with the phase of the high-frequency signal output to the connection conductor L3 from the terminal. Since the length of the connection conductor L2 is shorter than the length of the connection conductor L3 by １ ／ 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 is advanced by π. The high-frequency signals input to the hybrids H2 and H3 are converted into two high-frequency signals having a phase difference of π / 2.
Equally divided through holes TH1, TH2, TH3, TH
4 is output. These through holes TH1, TH
2, TH3, and TH4 have the same amplitude, 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 convenience of design, the hybrids H1 to H1 are usually
H3 is designed so that the input / output impedance becomes 50Ω. On the other hand, the excitation impedance of the radiating element 111 is different from 50Ω, so that the matching circuits M1 to M4 composed of stripline stubs allow the hybrid H2,
The impedance between each output terminal of H3 and each radiating element 111 is matched.

4 are arranged rotationally symmetrically at 90 ° intervals from each other.
The two helical radiating elements 111 are excited by high-frequency signals having the same amplitude which are sequentially different in phase by π / 2 along a predetermined rotation direction, so that circularly polarized waves are radiated into space.

In the above description, the case where the antenna is used as a transmitting antenna has been described. However, when the antenna is used as a receiving antenna, this embodiment receives a circularly polarized wave and outputs it from the coaxial connector 5.

The helical antenna according to this embodiment has an advantage common to the helical antenna in that both the directivity and the bandwidth are wide. Further, the helical antenna according to the present embodiment has the impedance characteristics of the hybrids 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 patterns of the substrates 3 and 10. Since the formation error of the substrates 3 and 10 can be easily reduced, the impedance characteristics can be easily improved. In addition, since each output terminal of the hybrids H2 and H3 and each radiating element 111 are connected to each other at a very short distance by each pin 15, a power supply loss is extremely small. Further, the variation of the excitation amplitude ratio and the excitation phase difference of each radiating element 111 is also determined mainly by the formation error of the conductor pattern of the substrates 3 and 10. Therefore, these formation errors are reduced to reduce the variation of the excitation amplitude ratio and the excitation phase difference. It is easy to reduce the distortion and directivity distortion.

[0030]

As described above, the helical antenna according to the present invention comprises a planar power divider for dividing a high-frequency signal into four equal parts, and a cylindrical dielectric connected to four output terminals of the power divider. and a four radiating elements arranged in a spiral shape on the peripheral surface of the member, it is possible and supporting child can have a high rigidity radiating elements with a simple structure, strong vibration and shock. In addition, the helical antenna according to the present invention can reduce the distance from the output end of the power divider to the excitation point of each radiating element, and the power divider has a planar structure and good impedance characteristics, thereby reducing feed loss. it can. Further, since the power divider having the planar structure can accurately control the power division ratio and the phase difference between the divided powers, the directivity distortion can be controlled. 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, so that the effect of reducing matching loss can be obtained.

[Brief description of the 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 / quadrature helical antenna.

FIG. 6 is a block diagram of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1: Mounting plate 2, 9, 31; Dielectric plate 3, 10; Substrate 4: Holding plate 5; Coaxial connector 6, 7, 8; Terminating resistance 11; Film element 22; Dielectric member 23, 111;

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromasa Kato 3-50-1 Ueishihara, Chofu-shi, Tokyo Anten Co., Ltd. (72) Inventor Kazuo Sekiya 3-50-1 Ueishihara, Chofu-shi, Tokyo Ante (56) References JP-A-61-25301 (JP, A) JP-A-1-264003 (JP, A) JP-A-3-74906 (JP, A) JP-A-62-43906 (JP, A) JP-A-60-214607 (JP, A) JP-A-54-102942 (JP, A) JP-A-4-26203 (JP, A) Japanese Utility Model Laid-open No. 58-114608 (JP, U) (58) Surveyed fields (Int.Cl. ⁶ , DB name) H01Q 11/08 H01Q 21/24

Claims (4)

(57) [Claims] 1. A plane which divides a high-frequency signal input from an input terminal into four equal parts and sequentially outputs the signals at four output terminals provided at four equally-divided points of a predetermined circle at different phases by π / 2. A power distributor having a structure and a cylindrical dielectric member arranged in alignment with the circumference of the predetermined circle and spirally disposed on a peripheral surface of the dielectric member. have a four radiating elements which are electrically connected respectively to the four output terminals of the vessel,
The power distributor includes a metal mounting plate and a surface and a surface of the mounting plate.
And a pair of dielectric plates stacked on the back and back of each dielectric plate
A pair of substrates superposed on the sides, said substrate being a dielectric
A metal thin film on both sides of a conductive plate,
The metal thin film on the body plate side constitutes a strip line circuit.
A helical antenna characterized by being formed into a conductor pattern . 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 foamable resin is filled inside the body member. 3. The conductor on one substrate of the power distributor.
The pattern includes a first hybrid that bisects a high-frequency signal input from the input terminal into two signals having mutually different phases, and two output terminals of the first hybrid having a length equal to the wavelength of the high-frequency signal. ¼ two different helical antenna according to claim 1 or 2, characterized by being composed of the second and third hybrids which are respectively connected via connecting lines. 4. A planar matching circuit is interposed between the second and third hybrids and the output terminal .
The conductor pattern on the other substrate of the power distributor is
4. The device according to claim 3, wherein said matching circuit is formed.
The helical antenna according to 1.