JP2011009836A - Multi-frequency shared antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-frequency shared antenna capable of easily setting and adjusting a stop band zone.SOLUTION: The wavelength of frequencies fα, fβ, and fγ (fα<fβ<fγ) is referred to as λα, λβ, and λγ (λα>λβ>λγ). The element length of a crank-like linear antenna (first radiating element) composed of a first L-shaped individual part 121 and a common part 123 is set to λα/4. The element length of a crank-like linear antenna (second radiating element) composed of a second L-shaped individual part 122 and the common part 123 is set to λγ/4. The element length of a U-shaped part (ends opening element) composed of the first individual part 121 and the second individual part 122 is set to λβ/2. Thus, the first radiating element transmits and receives a signal of the frequency fα (wavelength λα), the second radiating element transmits and receives a signal of the frequency of fγ (wavelength λγ), and the ends opening element prevents transmission and reception of a signal of the frequency fβ (wavelength λβ).

Description

  The present invention relates to a multi-frequency shared antenna that covers a plurality of frequency bands.

Conventionally, a multi-frequency shared antenna having a single feeding point and resonating in a plurality of frequency bands is known.
As one of this type of antenna, Patent Document 1 discloses a first monopole antenna whose resonance frequency band is set to the first frequency band, and the same feeding point as that of the first monopole antenna. Two second monopole antennas having a frequency band set to a second frequency band different from the first frequency band, the second monopole antenna being parallel to and sandwiching the first monopole antenna, and There is disclosed a multi-frequency monopole antenna arranged so that the distance L between the first monopole antenna and the first monopole antenna is equal.

  Patent Document 2 and Non-Patent Document 1 describe a plate-like antenna element that operates in a wide band, and a plate-like resonator that conducts with the antenna element and resonates in a stop band set within the operation band of the antenna element. Are arranged so as to face each other (with a dielectric substrate in between), thereby disclosing an antenna device that operates outside the stop band.

JP 2008-79246 A JP 2006-340202 A

Toshihiro Nakamura, Hisao Iwasaki, "Planar monopole antenna for UWB with stopband" IEICE Transactions B, 2006/9 Vol.J89-B, No.9, pp.1624-1632

  By the way, from the viewpoint of interference, the multi-frequency shared antenna should not radiate radio waves as much as possible other than the desired frequency, that is, have a stop band, and it is easy to set and adjust the stop band. desirable.

  However, in the conventional devices described in Patent Document 2 and Non-Patent Document 1, it is necessary to change the shape and size of the resonator when changing the stop frequency, and the degree of freedom of change is high. There was a problem that it was difficult.

  Moreover, in the conventional apparatus described in Patent Document 1, it is shown that resonance is performed at three frequencies by changing the antenna interval L, and no consideration is given to arbitrarily changing the stop band. It has not been.

  In order to solve the above-described problems, an object of the present invention is to provide a multi-frequency antenna that can easily set and adjust a stop band.

  The multi-frequency shared antenna according to claim 1, which is an invention made to achieve the above object, has an element length extending from the feed end to the open end while one end is open and the other end is connected to the same feed point. Are each provided with a radiating element portion composed of N radiating elements different from each other (N is an integer of 2 or more), and any radiating element pair arranged adjacent to each other is shared by both radiating elements on the feeding end side. The two radiating elements having a part and an individual part other than the shared part on the open end side and constituting the radiating element pair have one element length so as to radiate signals of two different wavelengths λα and λγ. Is set to λα / 4, the other element length is set to λγ / 4, and the total element length of the individual portions excluding the shared portion is λβ / 2 (where λα> λβ> λγ). The common part and the length of the individual part are set. And features.

  In the multi-frequency shared antenna of the present invention thus configured, the length excluding the shared portion of the radiating element pair (the portion obtained by combining the individual portions of both radiating element pairs) has a length λβ / 2 where both ends are open. Since the current flowing through the open-ended element cancels out at the frequency of the wavelength λβ, the emission of the signal of that frequency (the signal having the wavelength λβ) is suppressed.

  Therefore, according to the multi-frequency shared antenna of the present invention, a stop band that is a frequency band having a smaller gain than the pass band is formed between the pass bands that are the frequency bands having the wavelengths λα and λγ. Unwanted emission of radio waves outside the passband can be suppressed.

In addition, according to the multi-frequency shared antenna of the present invention, the stop band can be easily adjusted only by changing the lengths of the shared part and the individual part.
By the way, as for the two radiating elements which comprise the said radiating element pair, the said separate site | part may mutually be connected via the reactance element, as described in Claim 2.

In this case, by adjusting the value of the reactance element, the stop band can be easily changed without changing the radiating element.
Note that there is a capacitance (that is, reactance) between the two radiating elements forming the radiating element pair, and the value varies depending on the relative positional relationship between the two radiating elements and the shape of the two radiating elements.

  Therefore, as for the two radiating elements constituting the radiating element pair, the reactance component generated between the two radiating elements may be adjusted according to the relative positional relationship between the two radiating elements as described in claim 3. However, as described in claim 4, the reactance component generated between the two radiating elements may be adjusted according to the shape of the two radiating elements.

The radiating element portion may be configured by a pattern formed on a dielectric substrate as described in claim 5.
In this case, the multi-frequency antenna according to the present invention can be easily manufactured, and the wavelength is shortened by the dielectric constant of the dielectric substrate, so that the radiating element and thus the entire antenna can be downsized.

  In addition, the multi-frequency antenna according to the present invention includes two radiating element portions as described in claim 6, and the radiating element portions are arranged symmetrically with respect to an axis passing through the feeding point. Also good.

1 is an overall configuration diagram of a multi-frequency antenna according to a first embodiment. Explanatory drawing which shows the size of a radiation | emission element part, and the graph which shows the simulation result of the characteristic (return loss) of an antenna. The whole block diagram of the modification of 1st Embodiment. The whole block diagram of the multi-frequency antenna according to the second embodiment. The graph which showed the simulation result for showing the influence which the reactance value has on the characteristic of an antenna. The whole block diagram of the modification of 2nd Embodiment. The whole block diagram of the modification of 2nd Embodiment. The whole block diagram of the multifrequency shared antenna of 3rd Embodiment. The whole block diagram of the modification of 3rd Embodiment. The whole block diagram of the modification of 3rd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
<Overall configuration>
FIG. 1 is an overall configuration diagram of a multi-frequency shared antenna (hereinafter simply referred to as “antenna”) 10 of the first embodiment.

  As shown in FIG. 1, an antenna 10 includes a power feeding unit 11 grounded to a ground plate G made of a flat metal and a metal wire, and radiates a radio wave by receiving power from the power feeding unit 11. Part 12.

<Configuration of radiation element>
Each of the radiating element portions 12 is formed in an L shape, and is perpendicular to the ground plane G and the first and second individual portions 121 and 122 formed in a U shape by connecting one end of each. A common structure in which one end (hereinafter also referred to as “power supply end”) is connected to the power supply unit 11 and the other end (hereinafter also referred to as “branch end”) is connected to the connection ends of the first and second individual parts 121 and 122. It consists of part 123.

  Of the two straight portions constituting the L-shape of the first and second individual parts 121 and 122, straight portions (hereinafter also referred to as “connecting portions”) 121a and 122a on the side having the connecting ends are aligned with each other. And it is installed so as to be parallel to the ground plane G. The other straight portions (hereinafter also referred to as “radiating portions”) 121 b and 122 b of both the individual parts 121 and 122 are installed so as to be parallel to each other and perpendicular to the ground plane G.

  Hereinafter, a crank-shaped linear antenna composed of the first individual part 121 and the common part 123 is referred to as a first radiating element, and a crank-shaped linear antenna composed of the second individual part 122 and the common part 123 is referred to as The U-shaped part composed of the second radiating element, the first individual part 121 and the second individual part 122 is also referred to as an open-ended element.

  Moreover, as shown to Fig.2 (a), each site | part length of the 1st individual site | part 121, the 2nd individual site | part 122, and the common site 123 is represented by A1, A2, B, and each site | part of connection part 121a, 122a The length is represented by C / 2, and the total length is represented by C.

  Then, assuming that the wavelengths of the frequencies fα, fβ, and fγ (where fα <fβ <fγ) are λα, λβ, and λγ (that is, λα> λβ> λγ), the element length R1 (= A1 + B) of the first radiating element is λα. / 4, the element length R2 (= A2 + B) of the second radiating element is set to λγ / 4, and the element length R3 (= A1 + A2) of the both-end open element is set to λβ / 2.

<Operation>
In the antenna 10 configured as described above, the first radiating element (the first individual portion 121 and the common portion 123) transmits and receives a signal having the frequency fα (wavelength λα), and the second radiating element (the second individual portion 122 and the common portion is shared). The part 123) transmits and receives a signal having the frequency fγ (wavelength λγ), and the open-ended elements (the first individual part 121 and the second individual part 122) block the transmission and reception of the signal having the frequency fβ (wavelength λβ).

  That is, in the both-end open element, the connecting portions 121a and 122a parallel to the ground plane G do not contribute to signal radiation, and the radiation portions 121b and 122b perpendicular to the ground plane G contribute to signal radiation. When a signal in the vicinity of the frequency fβ resonates with an open-ended element, the current flowing through the radiating portion 121b and the current flowing through the radiating portion 122b are in opposite directions, and the magnetic field generated by the current cancels out. Signal emission is blocked near fβ.

<Effect>
As described above, according to the antenna 10, a stop band that is a frequency band with a smaller gain than the pass band is formed between the pass bands that are the frequency bands having the wavelengths λα and λγ. Unwanted emission of radio waves outside the band can be suppressed.

  Here, FIG. 2B is a graph showing a result of obtaining the reflection loss (S-parameter reflection coefficient S11) of the antenna 10 by simulation. However, A1 = 102 mm, A2 = 87 mm, B = 2 mm, and C = 10 mm.

  From FIG. 2B, it can be seen that the vicinity of fα≈720 MHz and fγ≈850 MHz is the passband, the vicinity of fβ≈820 MHz is the stopband, and there is a difference of 15 dB or more between the passband and the stopband.

  Further, according to the antenna 10, the lengths of the individual parts A1, A2 and the common part B are adjusted as appropriate, and the length of the open-ended element length R3 (= A1 + A2) is changed to facilitate the stop band. Can be adjusted.

<Modification>
In the present embodiment, the radiating element portion 12 is made of a metal wire. However, as shown in FIG. 3A, the dielectric substrate is erected so that the pattern formation surface is perpendicular to the ground plane G. You may comprise by the pattern on P.

  In the present embodiment, the case where two radiating elements are included in the radiating element unit 12 has been described. However, as in the antenna 10a illustrated in FIG. It may exist above.

  In this case, assuming that there are N radiating elements, there are N-1 radiating element pairs having radiating portions adjacent to each other, and at least one of the radiating element pairs has the relationship shown in the present embodiment. As long as it has.

  However, when the two radiating parts constituting the radiating element pair are located on different sides across the branch end of the common part, the common part, that is, from the branch end to the feeding end, as in the antenna 10 described above, If the two radiation parts are located on the same side with respect to the branch end of the common part, the common part from the connection point between the radiation part near the branch end and the connection part to the feeding end, What is necessary is just to make another part into an individual part.

Further, the radiating element portion 12 of the antenna 10a may be configured by a pattern on the dielectric substrate P standing on the ground plane G, similarly to the case shown in FIG.
[Second Embodiment]
Next, a second embodiment will be described.

<Overall configuration>
FIG. 4 is an overall configuration diagram of the antenna 20 of the present embodiment.
As shown in FIG. 4, the antenna 20 includes a power feeding unit 21 and a radiating element unit 22 as with the antenna 10.

The power feeding unit 21 is configured in exactly the same way as the power feeding unit 11.
Similarly to the radiating element unit 12, the radiating element unit 22 includes first and second individual parts 221 and 222 including a connecting part 221a and 222a and radiating parts 221b and 222b, and a common part 223. A reactance element 224 for connecting the portions 221b and 222b is provided.

That is, the both-end open element composed of the first and second individual parts 221 and 222 and the reactance element 224 are connected in parallel (or in a loop).
<Reactance element>
The reactance element 224 includes a capacitor, an inductor, or a combination thereof, and may be a variable capacitor or a variable inductor.

  However, since the resistance component becomes a loss and causes a gain reduction, it is desirable that the resistance component is not included in the reactance element 224 as much as possible. Further, it is desirable that the connection point of the reactance element 224 is near the tips (open ends) of the first and second individual parts 221 and 222.

<Operation>
In the antenna 20 configured as described above, by changing the value of the reactance element 224, the resonance frequency of the open-ended element including the reactance element 224, that is, the blocking frequency at which signal transmission / reception is blocked is changed.

  However, when a capacitive element (for example, a capacitor) is used as the reactance element 224, the blocking frequency is low, and when an inductive element (for example, an inductor) is used, the blocking frequency is high.

  That is, there is a capacity (that is, reactance) between the individual parts 221 and 222, in particular, between the radiation parts 221b and 222b arranged in parallel even when the reactance element 224 is not connected. It is considered that the resonance frequency of the parallel circuit formed by the capacitance and the open-ended element becomes the blocking frequency. For this reason, when the reactance between the radiating portions 221b and 222b is changed by connecting the reactance element 224, the resonance state changes, and consequently, the blocking frequency changes.

  On the other hand, the current distribution on the first radiating element composed of the first individual part 221 and the common part 223 or the second radiating element composed of the second individual part 222 and the common part 223 is important for the passing frequency. Since the influence of the reactance between 221 and 222 is small, it is considered that even if the reactance element 224 is changed, it does not change greatly.

<Effect>
As described above, according to the antenna 20, not only the same effect as that of the antenna 10 of the first embodiment is obtained, but also the value of the reactance element 224 is changed as appropriate to change the first and second radiating elements. The stopband can be easily changed without adding.

  Here, FIG. 5 is a graph showing a result of obtaining the reflection loss (S-parameter reflection coefficient S11) of the antenna 20 by simulation. 5A shows a case where a capacitive element (−1000Ω) is connected as the reactance element 224, FIG. 5B shows a case where the reactance element 224 is not connected, and FIG. 5C shows an induction as the reactance element 224. This shows a case where a conductive element (+ 1000Ω) is connected.

  From FIG. 5, it can be seen that the stop frequency fβ is decreased by connecting the capacitive reactance element 224, and the stop frequency fβ is increased by connecting the inductive reactance element 224.

<Modification>
In the present embodiment, the radiating element portion 22 is made of a metal wire. However, as shown in FIG. 6A, the dielectric substrate is erected so that the pattern formation surface is perpendicular to the ground plane G. You may comprise by the pattern on P.

  In the present embodiment, the case where there are two radiating elements constituting the radiating element unit 22 has been described, but there are three radiating elements constituting the radiating element unit 22 as in the antenna 20a shown in FIG. It may exist above.

  In this case, assuming that there are N radiating elements, there are N-1 radiating element pairs having radiating portions adjacent to each other, and at least one of them (all in FIG. 6B) is radiated. A reactance element 224 may be connected between the element pair.

  In this embodiment, the reactance between the first and second individual parts 221 and 222 is adjusted by providing the reactance element 224. Instead of providing the reactance element 224, the antenna 20b shown in FIG. As described above, by reacting the radiating portions 221b and 222b of the first and second individual parts 221 and 222 from the vertical direction with respect to the ground plane G, the reactance (here, the capacity) between the radiating portions 221b and 222b is adjusted. You may comprise as follows.

  7B, the reactance between the radiating portions 221b and 222b (here, the radiating portions 221b and 222b is bent by bending the shapes of the radiating portions 221b and 222b of the first and second individual portions 221 and 222). The capacity may be adjusted.

  That is, in either case of the antennas 20b and 20c, the capacity can be increased by reducing the distance between the radiating portions of both individual parts, and the capacity can be decreased by moving away.

Further, the radiating element portion 22 of the antennas 20a, 20b, and 20c may be configured by a pattern on the dielectric substrate P erected on the ground plane G, similarly to the case shown in FIG.
[Third Embodiment]
Next, a third embodiment will be described.

<Overall configuration>
FIG. 8 is an overall configuration diagram of the antenna 30 of the present embodiment.
As shown in FIG. 8, the antenna 30 includes a power feeding unit 31 and first and second radiation element units 32 and 33 that are configured by a metal wire and radiate radio waves by receiving power from the power feeding unit 11. Become.

The power feeding unit 31 is configured in the same manner as the power feeding unit 11.
Further, like the radiating element part 12, one radiating element part 32 is configured by the first and second individual parts 321 and 322 and the common part 323, and the other radiating element part 33 is also the same as the radiating element part 12. In addition, the first and second individual parts 331 and 332 and the common part 333 are configured.

However, the first radiating element portion 32 and the second radiating element portion 33 are arranged at positions symmetrical with respect to an axis passing through the power feeding portion 31 (a position corresponding to the surface of the ground plane G in the first embodiment). .
<Effect>
According to the antenna 30 configured as described above, since the antenna 30 has the same characteristics as the antenna 10 of the first embodiment, the same effect can be obtained and the ground plane G cannot be secured. Can also be installed.

<Modification>
In the present embodiment, the radiating element portions 32 and 33 are configured by metal wires, but may be configured by a pattern on the dielectric substrate P as shown in FIG.

  In the present embodiment, the case where there are two radiating elements constituting the radiating element portions 32 and 33 has been described. However, as in the antenna 30a illustrated in FIG. 9B, the radiating elements constituting the radiating element portions 32 and 33 are provided. There may be more than two elements.

  Further, the radiating element portions 32 and 33 are similar to the radiating element portions 22 of the antennas 20, 20a, 20b, and 20c of the second embodiment, as in the antennas 30b to 30e shown in FIGS. It may be configured.

  Further, the antennas 30b to 30e may be configured by the pattern on the dielectric substrate P in the same manner as the radiation element portions 32 and 33 shown in FIG.

  10, 10 a, 20, 20 a to 20 c, 30, 30 a to 30 e... Multi-frequency shared antenna 11, 21, 31, feeding unit 12, 22, 32, 33, radiating element unit 121, 122, 221, 222, 321, 322 , 331, 332... Individual parts 121 a, 122 a, 221 a, 222 a... Connection part 121 b, 122 b, 221 b, 222 b ... radiation part 123, 223, 323, 333 ... common part 224 ... reactance element G ... ground plane P ... dielectric substrate

Claims (6)

One end is opened and the other end is connected to the same feeding point, and the radiating element unit is composed of N (N is an integer of 2 or more) radiating elements having different element lengths from the feeding end to the opening end.
Arbitrary radiating element pairs arranged adjacent to each other have a shared part shared by both radiating elements on the feeding end side, and an individual part other than the shared part on the open end side,
The two radiating elements constituting the radiating element pair have one element length set to λα / 4 and the other element length set to λγ / 4 so as to radiate signals of two different wavelengths λα and λγ, and The lengths of the common part and the individual part are set so that the total element length of the individual parts excluding the common part is λβ / 2 (where λα>λβ> λγ). Multi-frequency antenna.   2. The multi-frequency antenna according to claim 1, wherein the two radiating elements constituting the radiating element pair are connected to each other through a reactance element.   3. The reactance component generated between the two radiating elements is adjusted according to the relative positional relationship between the two radiating elements in the two radiating elements constituting the radiating element pair. Multi-frequency antenna as described.   3. The multi-frequency according to claim 1, wherein the two radiating elements constituting the radiating element pair have a reactance component generated between the two radiating elements adjusted according to a shape of the both radiating elements. Shared antenna.   The multi-frequency antenna according to any one of claims 1 to 4, wherein the radiating element section is configured by a pattern formed on a dielectric substrate.   6. The multi-frequency device according to claim 1, comprising two radiating element portions, the radiating element portions being arranged symmetrically with respect to an axis passing through the feeding point. Shared antenna.