JP6052344B2 - 3 frequency antenna - Google Patents

Description

  The present invention is used in a base station for mobile communication such as a mobile phone, a PHS (Personal Handy-phone System), or a portable information terminal, for example, and can emit radio waves in three different frequency bands. It relates to a frequency sharing antenna.

  Conventionally, as a base station antenna used for mobile communication such as a cellular phone, an omnidirectional antenna that can be shared in a plurality of frequency bands and has a circular area centered on the base station is known. (For example, refer to Patent Document 1).

  The frequency sharing omnidirectional antenna described in Patent Document 1 includes a cylindrical reflector made of a conductor, a pair of first half-wave dipole antenna elements arranged with the reflector interposed therebetween, and a pair of first antennas. A pair of second half-wavelength dipole antenna elements are disposed so as to sandwich the reflector so as not to overlap with the half-wavelength dipole antenna elements. The use center frequency of the radiated wave radiated from the pair of first half-wavelength dipole antenna elements is different from the use center frequency of the radiated wave radiated from the pair of second half-wavelength dipole antenna elements. Communication in a plurality of frequency bands is possible.

  In addition, the present applicant has proposed a dual-frequency omnidirectional antenna described in Patent Document 2 for the main purpose of reducing the installation space. This dual-frequency omnidirectional antenna has a plurality of dual-frequency shared antenna elements, and two dual-frequency shared antenna elements adjacent in the vertical direction are provided point-symmetrically. Each dual-frequency antenna element is provided on the dielectric substrate and the surface of the dielectric substrate, and is provided on the surface of the dielectric substrate so as to be parallel to the dipole antenna that resonates at the frequency F1. And a parasitic element that resonates at a frequency F2 that is higher than the frequency F1. The arrangement positions of the parasitic elements with respect to the dipole antenna are different from each other between the dual-frequency antenna elements adjacent in the vertical direction.

JP 2002-198731 A JP 2010-10990 A

  By the way, in recent years, portable information terminals that receive a lot of information such as so-called smartphones have become widespread, and there is a movement to allocate a new frequency band for mobile communication because a sufficient communication speed cannot be secured in the existing frequency band. . In this case, the antenna for the base station needs to support more frequency bands.

  According to the dual-frequency omnidirectional antenna described in Patent Document 2, it is possible to reduce the installation space compared to the one described in Patent Document 1, but to increase the frequency band of the radiated radio wave. For example, when adding a parasitic element as shown in FIG. 4B described later, it is necessary to increase the width of the dielectric substrate. For this reason, the installation space of an antenna will increase.

  Therefore, the present invention provides a three-frequency shared antenna capable of reducing the installation space as compared with the case where two parasitic elements are arranged in parallel with a dipole antenna on one surface of a dielectric substrate. Objective.

  In order to solve the above-mentioned problems, the present invention provides a three-frequency shared antenna in which a plurality of three-frequency shared antenna elements provided on a dielectric substrate are provided in parallel in the longitudinal direction of the dielectric substrate. The three-frequency shared antenna element is provided on the dielectric substrate along the longitudinal direction, resonates in a first frequency band, and is provided on the dielectric substrate in parallel with the dipole antenna, A first parasitic element that resonates in a second frequency band different from the first frequency band; and provided on the dielectric substrate in parallel with the dipole antenna; and the first frequency band and the second frequency band, Comprising: a second parasitic element that resonates in a different third frequency band; and a feed line that supplies a feed signal in the first to third frequency bands to the dipole antenna. The antenna has a pair of radiating elements formed only on the surface of the dielectric substrate, and the feed line is formed only on the back surface of the dielectric substrate, and the pair of radiating elements, the first radiating element, The coupling element is formed in parallel with the parasitic element and the second parasitic element and capacitively couples with the pair of radiating elements, and the coupling section is more dielectric than the second parasitic element. Provided is a three-frequency shared antenna formed at a position far from an end portion where the second parasitic element is provided in the width direction of a body substrate.

  The dipole antenna is connected to a grounding portion provided on the dielectric substrate so as to extend in the longitudinal direction, and two of the three frequency sharing antenna elements adjacent in the longitudinal direction are connected to the grounding portion. The position of the antenna and the positions of the first and second parasitic elements with respect to the dipole antenna may be opposite to each other.

  The center frequency of the second and third frequency bands is higher than the center frequency of the first frequency band and less than twice the center frequency of the first frequency band, and the longitudinal direction It is preferable that an interval between the center positions in the longitudinal direction of the two three-frequency shared antenna elements adjacent to each other is less than the wavelength of the center frequency of the second and third frequency bands.

  The width of the dielectric substrate in the short direction may be less than a quarter of the wavelength of the center frequency of the first frequency band.

  The feeding line is provided between a distributor that distributes the feeding signal to two of the three frequency sharing antenna elements adjacent in the longitudinal direction, and one of the three frequency sharing antenna elements and the distributor. It is preferable to have a phase delay unit.

  According to the three-frequency shared antenna according to the present invention, the installation space can be reduced as compared with the case where two parasitic elements are arranged in parallel with the dipole antenna on one surface of the dielectric substrate.

The principal part of the 3 frequency sharing antenna which concerns on this Embodiment is shown, (a) shows the surface, (b) shows the back surface on the opposite side, respectively. (A) is the sectional view on the AA line of Fig.1 (a), (b) is the sectional view on the BB line of Fig.1 (a). It is a graph which shows VSWR of a 3 frequency shared antenna. It is explanatory drawing for demonstrating the effect of this Embodiment, (a) shows the 3 frequency shared antenna which concerns on this Embodiment, (b) shows the 3 frequency shared antenna as a comparative example.

  FIG. 1 shows the main part of a three-frequency shared antenna according to the present embodiment, where (a) shows the front (front) surface and (b) shows the opposite back surface. In (b), the shape of the antenna element or the like on the surface is indicated by a broken line. 2A is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 2B is a cross-sectional view taken along line BB of FIG. In FIGS. 2A and 2B, the thickness dimension of each part is exaggerated for the sake of explanation.

  The three-frequency shared antenna 100 includes a first antenna element 1 and a second antenna element 2 as a three-frequency shared antenna element, and a dielectric substrate 3. The dielectric substrate 3 is made of a dielectric material such as fluororesin (PTFE) or polyphenylene ether (PPE), and has a long plate shape. The first antenna element 1 and the second antenna element 2 are provided on the dielectric substrate 3 in parallel in the longitudinal direction. The dielectric substrate 3 is provided with a grounding portion 4 and a feed line 5 extending in the longitudinal direction.

  The first antenna element 1 includes a dipole antenna 10, a first parasitic element 11, and a second parasitic element 12. The dipole antenna 10 and the first parasitic element 11 are provided on the surface 3 a of the dielectric substrate 3. The second parasitic element 12 is provided on the back surface 3 b of the dielectric substrate 3.

  The dipole antenna 10 includes a pair of radiating elements 10a and 10b. The radiating element 10a and the radiating element 10b are formed so as to extend along the longitudinal direction of the dielectric substrate 3 with the gap 10c interposed therebetween. One end of the radiating element 10 a on the gap portion 10 c side is connected to the ground portion 4 by a connection portion 10 d extending along the short direction of the dielectric substrate 3. In addition, one end of the radiating element 10 b on the gap 10 c side is connected to the grounding portion 4 by a connection portion 10 e extending along the short direction of the dielectric substrate 3.

  The first parasitic element 11 is provided in a straight line parallel to the pair of radiating elements 10 a and 10 b of the dipole antenna 10. The first parasitic element 11 is provided at a position between the pair of radiating elements 10 a and 10 b between the first parasitic element 11 and the grounding portion 4 in the short direction of the dielectric substrate 3. The length of the first parasitic element 11 in the longitudinal direction of the dielectric substrate 3 is the length of the dipole antenna 10 (the length of the pair of radiating elements 10a and 10b and the gap portion 10c in the longitudinal direction of the dielectric substrate 3). Is also shorter than one half of the length of the dipole antenna 10.

  The second parasitic element 12 is linearly provided in parallel with the pair of radiating elements 10 a and 10 b and the first parasitic element 11 of the dipole antenna 10. As shown in FIGS. 1B and 2A, the second parasitic element 12 is provided at a position facing the first parasitic element 11 with the dielectric substrate 3 interposed therebetween. In the example shown in FIG. 1, the entire second parasitic element 12 faces the first parasitic element 11 with the dielectric substrate 3 interposed therebetween, but a part of the second parasitic element 12 is the dielectric substrate 3. May be opposed to the first parasitic element 11. The length of the second parasitic element 12 in the longitudinal direction of the dielectric substrate 3 is shorter than the length of the first parasitic element 11.

  The second antenna element 2 has a configuration similar to that of the first antenna element 1. That is, the second antenna element 2 has a dipole antenna 20, a first parasitic element 21, and a second parasitic element 22, and the dipole antenna 20 is congruent with the dipole antenna 10 and has the first parasitic element. The element 21 is congruent with the first parasitic element 11, and the second parasitic element 22 is congruent with the second parasitic element 12. The dipole antenna 20 and the first parasitic element 21 are provided on the surface 3 a of the dielectric substrate 3. The second parasitic element 22 is provided on the back surface 3 b of the dielectric substrate 3 so as to face the first parasitic element 21 and the dielectric substrate 3.

  However, the first antenna element 1 and the second antenna element 2 are the positions of the dipole antennas 10 and 20 with respect to the ground portion 4, and the first parasitic elements 11 and 21 and the second parasitic elements with respect to the dipole antennas 10 and 20. The positions of 12 and 22 are opposite to each other. That is, as shown in FIG. 1A, when viewed from the surface 3a side, the dipole antenna 10 of the first antenna element 1 is provided on the right side of the ground portion 4, and the first parasitic element 11 and the second parasitic element 11 The parasitic element 12 is provided on the further right side of the dipole antenna 10. On the other hand, the dipole antenna 20 of the second antenna element 2 is provided on the left side of the ground portion 4, and the first parasitic element 21 and the second parasitic element 22 are provided on the further left side of the dipole antenna 20.

  In the present embodiment, the first antenna element 1 and the second antenna element 2 are provided point-symmetrically around one point (indicated by the symmetry center point P in FIG. 1 (a)) of the three-frequency shared antenna 100. It has been. In other words, when the first antenna element 1 is rotated 180 ° about the symmetry center point P, it overlaps the second antenna element 2.

Further, as described above, the length of the first parasitic elements 11 and 21 is shorter than the length of the dipole antennas 10 and 20, and the length of the second parasitic elements 12 and 22 is the length of the first parasitic elements 11 and 21. Since it is shorter than the length, the dipole antennas 10 and 20 resonate in the _first frequency band B ₁ , the first parasitic elements 11 and 21 resonate in the second frequency band B ₂ , and the second parasitic element 12 , 22 resonate in the third frequency band B ₃ , the first frequency band B ₁ , the second frequency band B ₂ , and the third frequency band B ₃ are different from each other, and the second frequency band B ₂ is a frequency higher than the first frequency band B _1, the third frequency band B ₃ is a higher frequency than the second frequency band B _2.

The center frequency of the second and third frequency band B _2, B ₃ is a frequency higher than the first center frequency of the frequency band B _1, and less than 2 times the first center frequency of the frequency band B ₁ It is. The first to third frequency bands B ₁ , B ₂ , and B ₃ are, for example, a 1.9 GHz band, a 2.1 GHz band, and a 2.5 GHz band. The first to third frequency bands B ₁ , B ₂ , and B ₃ are 1.5 GHz band, 1.9 GHz band, 2.1 GHz band, or 1.7 GHz band, 1.9 GHz band, 2.1 GHz band. May be assigned.

In the present embodiment, the distance between the center position of the first antenna element 1 and the center position of the second antenna element 2 in the longitudinal direction of the dielectric substrate 3 (distance D shown in FIG. 1A) is set. , Less than the wavelength of the center frequency of the second and third frequency bands B ₂ and B ₃ . The width W _{1 in} the short direction of the dielectric substrate 3 is less than a quarter of the wavelength of the center frequency of the first frequency band B ₁ .

  The grounding portion 4 has a zigzag shape so as to avoid a region where the first antenna element 1 and the second antenna element 2 are provided. That is, in a region adjacent to the first antenna element 1 and the dielectric substrate 3 in the lateral direction, the grounding portion 4 is provided close to one side of the dielectric substrate 3 (left side in FIG. 1A). . Further, in a region adjacent to the second antenna element 2 and the dielectric substrate 3 in the short direction, the ground portion 4 is provided close to the other side of the dielectric substrate 3 (right side in FIG. 1A). It has been.

  In addition, a through hole 30 that penetrates the ground portion 4 and the dielectric substrate 3 in the thickness direction is formed at one place in the region where the ground portion 4 is provided. An outer conductor of a coaxial cable (not shown) connected to the wireless device is connected to the ground portion 4 in the peripheral portion of the through hole 30, and the ground portion 4 is grounded via the outer conductor.

  A feed point 50 to which the central conductor of the coaxial cable is connected is formed on the feed line 5. In addition, the feed line 5 includes a broadband two distributor 51 that distributes the feed signal supplied from the feed point 50 to the first antenna element 1 and the second antenna element 2, and a coupling portion on the first antenna element 1 side. 5a and the second antenna element 2 side coupling section 5b, and a broadband delay divider 51 and a phase delay section 52 provided between the coupling section 5b.

The feed point 50 is fed with feed signals of the first to third frequency bands B ₁ , B ₂ , and B ₃ . That is, the feed point 50 includes a signal in the first frequency band B ₁ radiated from the dipole antennas 10 and 20, a signal in the second frequency band B ₂ radiated from the first parasitic elements 11 and 21, and third supply signal a signal of a frequency band B ₃ is superimposed emitted is fed from the second parasitic element 12, 22.

  The coupling portion 5a is formed linearly along the longitudinal direction of the dielectric substrate 3 on the back surface 3b side of the pair of radiating elements 10a and 10b, and is capacitively coupled to the pair of radiating elements 10a and 10b of the dipole antenna 10. The coupling portion 5b is formed linearly along the longitudinal direction of the dielectric substrate 3 on the back surface 3b side of the pair of radiating elements 20a and 20b of the dipole antenna 20, and is capacitively coupled to the pair of radiating elements 20a and 20b.

The first parasitic elements 11 and 21 are fed with a signal in the second frequency band B ₂ by electromagnetic coupling with the dipole antennas 10 and 20. The second parasitic elements 12 and 22 are fed with a signal in the third frequency band B ₃ by electromagnetic coupling with the dipole antennas 10 and 20.

  The phase delay unit 52 is obtained by bending a part of the feed line 5 a plurality of times to increase the line length, and the phase of the signal supplied to the second antenna element 2 by the phase delay unit 52 is the first. The phase of the signal supplied to the antenna element 1 is delayed. Accordingly, when the three-frequency shared antenna 100 is installed in the base station so that the first antenna element 1 is positioned above the second antenna element 2 in the vertical direction, the vertical plane directivity of the three-frequency shared antenna 100 is set. Becomes downward from the horizontal direction.

  Dipole antennas 10, 20, first parasitic elements 11, 21, second parasitic elements 12, 22, ground portion 4, and feed line 5 are metal films formed on the front surface 3 a and the back surface 3 b of the dielectric substrate 3. It is provided as. That is, the first antenna element 1, the second antenna element 2, the ground portion 4, and the feed line 5 are formed by etching the metal film formed on the front surface 3 a and the back surface 3 b of the dielectric substrate 3. .

FIG. 3 shows a VSWR (Voltage Standing Wave) of the three-frequency shared antenna 100 when the first to third frequency bands B ₁ , B ₂ and B ₃ are 1.9 GHz band, 2.1 GHz band and 2.5 GHz band. Ratio is a graph showing a voltage standing wave ratio). In this graph, the horizontal axis represents frequency and the vertical axis represents VSWR. VSWR is an index of power efficiency. The smaller this value, the higher the power efficiency. When VSWR is 1.5, the power loss is about 4%. From this graph, it can be seen that radio waves are efficiently radiated in the first to third frequency bands B ₁ , B ₂ , and B ₃ .

  4A and 4B are explanatory diagrams for explaining the effect of the three-frequency shared antenna 100 according to the present embodiment. FIG. 4A shows the three-frequency shared antenna 100, and FIG. 4B shows the three-frequency shared antenna as a comparative example. An antenna 100A is shown. In FIG. 4A, the second parasitic elements 12 and 22 are indicated by solid lines and the other elements and the like are indicated by broken lines for the sake of explanation. Although not shown, the three-frequency shared antenna 100 </ b> A is also provided with the same feed line 5 as the three-frequency shared antenna 100.

  In the three-frequency shared antenna 100A, the second parasitic elements 12A and 22A of the first antenna element 1A and the second antenna element 2A are provided on the same surface as the dipole antennas 10 and 20 and the first parasitic elements 11 and 21. Accordingly, the configuration is the same as that of the three-frequency antenna 100 except that the width of the dielectric substrate 3A is larger than the width of the dielectric substrate 3. In the three-frequency shared antenna 100A, components common to the three-frequency shared antenna 100 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4B, the second parasitic element 12A of the three-frequency shared antenna 100A is provided on the right side (the side opposite to the dipole antenna 10) of the first parasitic element 11. That is, the dipole antenna 10, the first parasitic element 11, and the second parasitic element 12A are arranged in this order on the same surface of the dielectric substrate 3A. Further, the second parasitic element 22A of the three-frequency shared antenna 100A is provided on the left side of the first parasitic element 21 (on the side opposite to the dipole antenna 20). That is, the dipole antenna 20, the first parasitic element 21, and the second parasitic element 22A are arranged in this order on the same surface of the dielectric substrate 3A. The size and shape of the second parasitic elements 12A and 22A are the same as the second parasitic elements 12 and 22 of the three-frequency shared antenna 100.

Thus, the width W ₂ in the lateral direction of the dielectric substrate 3A is 3 than the width W ₁ in the lateral direction of the dielectric substrate 3 of the band antenna 100, the second parasitic elements 12A, in order to provide 22A It is getting bigger as needed.

Further, parallel to the longitudinal direction of the dielectric substrate 3, and the lateral direction (FIG. 4 (right direction in a)) to a second distance D ₁ from the parasitic element 12 spaced apart imaginary line linear dielectric substrate 3 and L _1, parallel to the longitudinal direction of the dielectric substrate 3A, and spaced from the second parasitic element 12A in the lateral direction of the dielectric substrate 3A (the right direction in FIG. 4 (b)) also a distance D ₁ linear when the imaginary line _{L 2} and the distance _{D 2} from the imaginary line _{L 1} to the second parasitic element 22 is shorter than the distance _{D 3} from the virtual line _{L 2} to the second parasitic element 22A _(D 1 < _{D 2} <D 3).

In the three-frequency antenna 100, the difference between the distance D ₁ and the distance D ₂ affects the phase difference Δp ₁ between the radio wave radiated from the second parasitic element 12 and the radio wave radiated from the second parasitic element 22. . Further, in the 3-frequency antenna 100A, the difference between the distance _{D 1} and the distance _{D 3} is radio wave to the phase difference Delta] p ₂ emitted from the radio wave radiated from the second parasitic element 12A and the second parasitic element 22A Affect. Since the distance _{D 3} is longer than the distance _{D 2,} the phase difference Delta] p ₁ in 3-frequency antenna 100, a difference between the phase difference Delta] p ₂ occurs in 3-band antenna 100A.

This is vertical when the three-frequency shared antennas 100 and 100A are installed in the base station along the vertical direction so that the first antenna elements 1 and 1A are positioned above the second antenna elements 2 and 2A. Affects surface directivity. That is, the phase difference between the signals of the first antenna elements 1 and 1A and the second antenna elements 2 and 2A is adjusted by the phase delay unit 52 (shown in FIG. 1B), but the distance D ₁ and the difference between the distance _{D 3,} the 3-frequency antenna 100A, with respect to the phase difference adjusted by the phase delay unit _52, the phase distance of D 1 -D ₃ is deviated. This phase shift is larger than the phase shift due to the difference between the distance D ₁ and the distance D ₂ in the case of the three-frequency shared antenna 100.

More specifically, in the case of FIG. 4, the phase difference Δp ₂ of the three-frequency shared antenna 100 A is larger than the phase difference Δp ₁ of the three-frequency shared antenna 100, thereby the vertical plane directivity of the frequency band B ₃ of 3, facing downward than the third vertical plane directivity of the frequency band B ₃ of 3 frequency antenna 100. Thereby, for example, when the three-frequency shared antenna 100A is installed at a high place such as a rooftop of a building such as a building or a radio tower, a range (communication range) where radio waves reach the ground is narrowed. In addition, when the positions of the virtual lines L ₁ and L ₂ are on the left side of the respective antennas, it is obvious that the vertical plane directivity is upward, contrary to the above.

  As described above, in the three-frequency antenna 100, the second parasitic elements 12 and 22 are provided on the back surface 3b of the dielectric substrate 3, thereby suppressing an increase in the width of the dielectric substrate 3 and radiating radio waves. The vertical plane directivity of is optimized.

  Next, effects other than the above obtained by the three-frequency shared antenna 100 according to the present embodiment will be described.

(1) Since the second parasitic elements 12 and 22 are provided on the back surface 3 b of the dielectric substrate 3, the dipole antennas 10 and 20 do not cause physical interference with the first parasitic elements 11 and 21. And the second parasitic elements 12 and 22 can be set to dimensions suitable for electromagnetic coupling. That is, in the three-frequency shared antenna 100A mentioned as the comparative example, the first parasitic elements 11 and 21 are interposed between the dipole antennas 10 and 20 and the second parasitic elements 12A and 22A. And the second parasitic elements 12A and 22A are limited in distance, and electromagnetic coupling between the two may be weakened. In the three-frequency shared antenna 100 according to the present embodiment, there is no problem.

(2) The first antenna element 1 and the second antenna element 2 are the positions of the dipole antennas 10 and 20 with respect to the ground portion 4, and the first parasitic elements 11 and 21 and the second antenna elements with respect to the dipole antennas 10 and 20. Since the positions of the parasitic elements 12 and 22 are opposite to each other, the horizontal plane directivity of the three-frequency shared antenna 100 can be made nearly omnidirectional. That is, the grounding portion 4 provided on the side of the first antenna element 1 and the second antenna element 2 (one side in the short direction of the dielectric substrate 3) also acts as a radio wave reflector. Therefore, the directivity in the direction opposite to the grounding portion 4 is increased. That is, the first antenna element 1 has a strong directivity on the right side of FIG. 1A, and the second antenna element 2 has a strong directivity on the left side of FIG. Therefore, by arranging the dipole antennas 10 and 20, the first parasitic elements 11 and 21, and the second parasitic elements 12 and 22 as described above, the first antenna element 1 and the second antenna element 2 The directivity can be complemented with each other, and the horizontal plane directivity of the three-frequency shared antenna 100 can be brought close to omnidirectionality.

(3) Since the second parasitic elements 12 and 22 are opposed to the first parasitic elements 11 and 21 with the dielectric substrate 3 in between, the second parasitic elements 12 and 22 do not cause an increase in the width of the dielectric substrate 3. Parasitic elements 12 and 22 can be provided.

(4) The distance between the center position of the first antenna element 1 and the center position of the second antenna element 2 (distance D: see FIG. 1A) is the second and third frequency bands B ₂ , B since less than the wavelength of the _third center frequency, it is possible to suppress the occurrence of grating lobes in the second and third vertical plane directivity of the frequency band B _2, B _3. That is, when the distance D is equal to the wavelength of the center frequency of the second and third frequency bands B ₂ and B ₃ , the equiphase surface is in the longitudinal direction of the dielectric substrate 3 (vertical direction when installed in the base station). Even if unnecessary strong radiation is generated and the gain decreases, setting the distance D as described above suppresses the generation of grating lobes and suppresses the increase in the longitudinal dimension of the three-frequency antenna 100. can do.

(5) Since the width W ₁ of the dielectric substrate 3 in the short direction is less than a quarter of the wavelength of the center frequency of the first frequency band B ₁ , the first width in the short direction of the dielectric substrate 3 The dipole antenna 10, the first parasitic element 11, and the second parasitic element 12 of the antenna element 1, and the dipole antenna 20, the first parasitic element 21, and the second parasitic element 22 of the second antenna element 2. And the side lobe in the vertical plane directivity can be reduced.

(6) Since the phase delay unit 52 is provided in the feed line 5 between the broadband two divider 51 and the coupling unit 5a, the signal fed to the first antenna element 1 and the second antenna element The phase difference with the signal fed to 2 can be adjusted appropriately.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above-described embodiments, the second frequency band _{B 3} to the second parasitic element 12 and 22 resonates at a second frequency higher than the frequency band _{B 2} of the first parasitic elements 11 and 21 resonates has been described some cases for the second frequency band B ₃ may be a low frequency than the second frequency band B _2.

  In addition, the three-frequency shared antenna 100 may be provided with a plurality of sets of the first antenna element 1 and the second antenna element 2. Further, as the elements constituting the first antenna element 1 and the second antenna element 2, a further parasitic element may be provided on the front surface 3 a or the back surface 3 b of the dielectric substrate 3. That is, if at least one of the plurality of parasitic elements constituting the first antenna element 1 and the second antenna element 2 is provided on the back surface 3b, the same effect as described above can be obtained.

DESCRIPTION OF SYMBOLS 1,1A ... 1st antenna element (3 frequency sharing antenna element), 2, 2A ... 2nd antenna element (3 frequency sharing antenna element), 3, 3A ... Dielectric substrate, 3a ... Front surface, 3b ... Back surface, DESCRIPTION OF SYMBOLS 4 ... Ground part, 5 ... Feed line, 5a, 5b ... Coupling part, 10, 20 ... Dipole antenna, 10a, 10b, 20a, 20b ... Radiation element, 10c, 20c ... Gap part, 10d, 10e, 20d, 20e ... Connection part, 11, 21 ... 1st parasitic element, 12, 22, 12A, 22A ... 2nd parasitic element, 30 ... Through-hole, 50 ... Feeding point, 51 ... Broadband two divider, 52 ... Phase delay part, 100, 100A ... 3 frequency shared antenna, L ₁ , L ₂ ... virtual line, P ... symmetry center point

Claims (5)

A plurality of three-frequency shared antenna elements provided on a dielectric substrate is a three-frequency shared antenna provided in parallel in the longitudinal direction of the dielectric substrate,
The three-frequency shared antenna element is
A dipole antenna provided along the longitudinal direction on the dielectric substrate and resonating in a first frequency band;
A first parasitic element provided on the surface of the dielectric substrate in parallel with the dipole antenna and resonating in a second frequency band different from the first frequency band;
A second parasitic element provided on the back surface of the dielectric substrate in parallel with the dipole antenna and resonating in a third frequency band different from the first frequency band and the second frequency band;
A feed line for supplying feed signals of the first to third frequency bands to the dipole antenna;
With
The dipole antenna has a pair of radiating elements formed only on the surface of the dielectric substrate,
The feeder line is formed only on the back surface of the dielectric substrate, and is formed in parallel with the pair of radiating elements, the first parasitic element, and the second parasitic element, and the pair of radiating elements. And a coupling portion that capacitively couples with
The coupling portion is formed at a position farther from the end where the second parasitic element in the width direction of the dielectric substrate is provided than the second parasitic element ;
The first parasitic element and the second parasitic element are opposed to each other across the dielectric substrate,
The three-frequency shared antenna in which the distance between the center of the pair of radiating elements and the first parasitic element is different from the distance between the center of the pair of radiating elements and the second parasitic element . The dipole antenna is connected to a grounding portion provided on the dielectric substrate so as to extend in the longitudinal direction,
In the two three-frequency shared antenna elements adjacent to each other in the longitudinal direction, the position of the dipole antenna with respect to the ground portion and the positions of the first and second parasitic elements with respect to the dipole antenna are opposite to each other.
The three-frequency shared antenna according to claim 1. The center frequency of the second and third frequency bands is higher than the center frequency of the first frequency band and less than twice the center frequency of the first frequency band,
The distance between the longitudinal center positions of two of the three frequency sharing antenna elements adjacent in the longitudinal direction is less than the wavelength of the center frequency of the second and third frequency bands.
The three-frequency shared antenna according to claim 1 or 2. The width in the short direction of the dielectric substrate is less than a quarter of the wavelength of the center frequency of the first frequency band.
The three-frequency shared antenna according to any one of claims 1 to 3. The feed line is a distributor that distributes the feed signal to two of the three frequency sharing antenna elements adjacent in the longitudinal direction, and a phase provided between one of the three frequency sharing antenna elements and the distributor. Having a delay part,
The three-frequency shared antenna according to any one of claims 1 to 4.

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