JP2004096210A - Surface-mounted antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounted antenna which is small and lightweight, suppresses the variations in center frequency even if print slippage of an electrode pattern occurs, and reduces time and effort for frequency adjustment. <P>SOLUTION: The surface-mounted antenna 9 has a substrate 1 consisting of a dielectric or a magnetic material, a radiation electrode 2 formed on at least one surface of the substrate 1, a grounding electrode 3 directly connected to one end of the electrode 2 and formed on the substrate 1, and a feeder electrode 4 opposing the electrode 2 with an interval. In this antenna, at least one sides 22a-22h of the electrode 2 and ridge lines 10a-10h of the substrate 1 forms gaps (d), and a ratio d/W of each gap (d) to the width W of the substrate is 0.05-0.2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface-mounted antenna used for a mobile phone or the like having a built-in GPS (Global Positioning System) and Bluetooth (Bluetooth) function.
[0002]
[Prior art]
FIG. 8 shows a conventional surface mount antenna (for example, see Patent Document 1). On the lower surface of the base 1, a ground electrode 3 having a shape in which a part of one side facing the power supply electrode 4 is cut is formed to extend to the ridge lines 10 e to 10 h of the base 1. On the upper surface of the base 1, a U-shaped radiation electrode 2 is formed extending to the ridge lines 10 a to 10 d of the base 1. Short-circuit conductors 71 and 72 for short-circuiting the radiation electrode 2 and the ground electrode 3 are formed on the side surface of the base 1. A feed electrode 4 extending from the lower surface of the base 1 to the upper surface via the side surface is formed, and functions as a 1/4 wavelength short-circuit type microstrip surface mount antenna.
[0003]
FIG. 9 shows another conventional example (for example, see Patent Document 2). A ground electrode 3 is formed on the entire lower surface of the base 1, and a radiation electrode 2 is formed on the entire upper surface of the base 1 up to the ridge lines 10 a to 10 d of the base 1. A power supply electrode 4 is formed on a side surface of the base 1, and the radiation electrode 2 is excited by a transmission signal input from the power supply terminal electrode 4, and operates as a transmission antenna by radiating radio waves. Further, the radiation electrode 2 is excited by the received radio wave, and a reception signal is output from the power supply electrode 4 to operate as a reception antenna. At this time, the power supply electrode 4 has a length of 波長 wavelength at the center frequency.
[0004]
A conventional method of manufacturing the surface mount antenna 9 will be described (for example, see Patent Documents 3 and 4). It is often obtained by printing a plurality of surface mount antennas at once and cutting them from a large substrate as if individual chips were separated from chocolate blocks. This is because productivity is significantly improved. For example, 16 surface mount antennas are patterned and printed on a large substrate at a time and processed, and finally cut into individual surface mount antennas.
[0005]
[Patent Document 1]
Japanese Patent No. 362002 [Patent Document 2]
Japanese Patent No. 362002 [Patent Document 3]
Japanese Patent Application Laid-Open No. 10-107537 [Patent Document 4]
JP 2001-119224 A
[Problems to be solved by the invention]
However, the grounds of the conventional surface-mount antenna 9 will be described later together with data, but analysis by the present inventors has revealed that the miniaturization is insufficient.
[0007]
In addition, since the radiation electrode 2 extends to the ridge lines 10a to 10d of the base 1, there are the following problems in manufacturing.
[0008]
That is, when printing each electrode on the base 1 in the manufacturing process, a so-called printing shift in which the electrode pattern is shifted from a desired position may occur. This is because printing in alignment with the ridge lines 10a to 10d of the base 1 requires considerable care in alignment.
When the electrode pattern shifts, the capacitance generated between the open end of the radiation electrode 2 and the ground electrode 3 increases or decreases, and as a result, the center frequency (resonance frequency) shifts from a desired value.
In order to correct such variations in the center frequency, complicated frequency adjustment operations such as trimming and notching of the electrode pattern were required.
Furthermore, when a plurality of surface-mounted antennas 9 are obtained by cutting from a large-sized substrate, a large number of defective products are generated if a printing shift occurs in which an electrode pattern is shifted from a desired position.
[0009]
Accordingly, it is an object of the present invention to provide a surface mount antenna capable of suppressing the variation of the center frequency even when the printing displacement of the electrode pattern occurs, reducing the trouble of frequency adjustment, and further reducing the size.
[0010]
[Means for Solving the Problems]
The first means of the present invention comprises a substrate 1 made of a dielectric or magnetic material, a radiation electrode 2 formed on at least one surface of the substrate 1, and a radiation electrode 2 formed on the substrate 1 by being directly connected to one end of the radiation electrode 2. A surface-mounted antenna 9 having a ground electrode 3 provided and a feed electrode 4 spaced apart from and facing the radiation electrode 2, wherein at least one side 22 a to 22 h of the radiation electrode 2 and a ridge line 10 a to 10 10h forms the gap d, and the ratio d / W between the gap d and the width W of the base is 0.05 to 0.2, which is the surface-mounted antenna 9.
Here, the direct connection means that one end of the radiation electrode 2 and the ground electrode 3 are electrically directly connected by a transmission line, a strip line, a pattern, or the like.
[0011]
The second means of the present invention comprises a substrate 1 made of a dielectric or magnetic material, a radiation electrode 2 formed on at least one surface of the substrate, and a radiation electrode 2 formed on the substrate 1 so as to be capacitively coupled to one end of the radiation electrode 2. A surface-mounted antenna 9 having a ground electrode 3 provided and a feed electrode 4 spaced apart from and facing the open end of the radiation electrode 2, wherein at least one side 22 a to 22 h of the radiation electrode 2 and the base 1 Ridge lines 10a to 10h form a gap d, and the ratio d / W between the gap d and the width W of the base is 0.05 to 0.2.
Here, the term “capacitive coupling” means that one end of the radiation electrode 2 and the ground electrode 3 are formed apart from each other, and are electrically connected and coupled via a capacitance.
[0012]
The present inventor has made effective use of the edge (edge) effect in the surface mount antenna so that an electrode pattern is equivalently present even in a portion having no electrode pattern due to a leakage electromagnetic field in the vicinity of the ridge line 10a or the like of the base 1. I found that I can handle it as if I did it.
Also, by making effective use of this, it is better to form an appropriate gap d than to extend to at least one or more of the ridge lines 10a to 10h of the base 1, so that the absorption of the misalignment of the electrode pattern and the radiation efficiency can be reduced. Both were found to be good.
[0013]
According to the first means of the present invention, even if printing misalignment of the electrode pattern occurs, variation in the center frequency can be suppressed. This is because the edge (edge) effect works effectively, and even if there is no electrode pattern, it can be handled as if the electrode pattern is equivalent even in a portion where there is no electrode pattern due to the leakage electromagnetic field in the vicinity of the ridge line 10a or the like of the base 1.
[0014]
According to the second means of the present invention, even if the printing deviation of the electrode pattern occurs, not only the variation of the center frequency can be suppressed, but also the capacitive coupling is used. May be arranged to face each other.
In this case, since the capacitive coupling with the opposite ground electrode 3 is strong, even if the power supply electrode 4 is arranged in the vicinity, the influence is relatively small. Therefore, when the center frequency is largely adjusted, the main adjustment of the frequency is performed by adjusting the coupling degree between the radiation electrode 2 and the second ground electrode, and the coupling degree between the radiation electrode 2 and the feeding electrode 4 is adjusted. By doing so, the frequency can be finely adjusted.
[0015]
In the surface mount antenna according to the present invention, it is more preferable that the corners of the radiation electrode 2 and / or the feed electrode 4 have rounded corners. This is because a sudden change does not occur in the path of the electromagnetic field, so that the loss is reduced.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a perspective view showing a surface mount antenna 9 according to a first embodiment of the present invention. In FIG. 1, the radiation electrode 2 is disposed on the upper surface of the base 1 so as to form a gap d from the ridge lines 10 a and 10 d of the base 1. In the surface mount antenna 9 having the width W of the base 1 of 4 mm, the length L of 10 mm, the height H of 3 mm, and the relative permittivity εr = 8, the ratio d / W between the gap d and the width W of the base 1 is set to 0. FIG. 2A shows the results of measuring the shift amount Δf ₀ [%] of the center frequency f ₀ , the normalized bandwidth [%], and the radiation efficiency [%] while changing the center frequency f ₀ . 2 to (c).
Here, _{f 0} the resonance frequency (center frequency) when the d / W value = 0, when the resonance frequency is f in the d / W value otherwise, the shift amount of the center frequency _{f 0} Delta] f ₀ = ( f−f ₀ ) × 100 / f ₀ [%]. The normalized bandwidth [%] is defined as BW / f × 100, where BW is the bandwidth at each other d / W value. When the input power is Pin and the radiation power is Pout, the radiation efficiency is defined as Pout × 100 / Pin [%].
[0017]
From FIG. 2 (a), the shift amount Delta] f ₀ of the center frequency _{f 0} is a monotonically decreasing function with respect to the ratio d / W. That is, the center frequency f corresponding to increase the ratio d / W means can be made smaller than f _0. Here, when the wavelength of the radio wave is λ (= c / f, where c is a constant value at the speed of light), the length L is proportional to λ / √εr. Can be shortened. That is, there is an effect of reducing the size of the surface mount antenna.
On the other hand, when the ratio d / W is increased, the normalized bandwidth decreases from FIG. 2B and the radiation efficiency decreases from FIG. 2C, so that the ratio d / W = 0.05 to 0 as the optimum range. 2 satisfies both the normalized bandwidth and the radiation efficiency while miniaturizing the surface mount antenna.
[0018]
FIG. 3 is a perspective view showing a surface mount antenna 9 according to a second embodiment of the present invention. The surface-mounted antenna 9 includes a radiation electrode 2 disposed on the upper surface of a rectangular parallelepiped base 1, a ground electrode 3 connected to one end of the radiation electrode 2, and a radiation electrode 2 on a side surface with a gap 1 therebetween. And the formed power supply electrode 4.
The surface mount antenna 9 has a configuration similar to that of the inverted F-type antenna, but differs in that the power supply electrode 4 is provided with a gap.
No electrodes other than the electrodes for soldering are arranged on the bottom surface 1a of the base 1, and the surface mount antenna is also mounted in an area without a ground conductor on the circuit board. An omnidirectional property indicating a radiation electric field pattern is obtained.
The power supply electrode 4 has a gate-shaped (U-shaped) shape obtained by bending a band-shaped electrode at two places, and has a parallel portion 41 that faces the ridge line 10a of the radiation electrode 2 almost in parallel. The power supply electrode 4 has a power supply point 43 connected to a power supply line of a transmission / reception circuit (not shown) at a power supply section 43 at one end, and has a ground end 42 connected to a ground conductor at a ground section 44 at the other end. . The power supply part 43 and the ground part 44 of the power supply electrode 4 mainly generate inductance, and the radiation electrode 2 and the parallel part 41 mainly form capacitance (capacitance).
[0019]
The radiation electrode 2, the ground electrode 3, and the power supply electrode 4 are not limited to the structure illustrated in FIG. 3, but it is preferable that the power supply electrode 4 be formed on one side surface of the base 1. There is no misregistration at the time of print formation, and it is easy to manufacture and stable in characteristics.
[0020]
In the surface-mounted antenna 9 shown in FIG. 3, the other end of the radiation electrode 2 is an open end 20. Although the gap d is provided in parallel with the ridge line 10a of the base 1, it may be provided in parallel with the orthogonal ridge line 10b or a combination of both. In this case, the open end 20 of the radiation electrode 2 is disposed inside the ridge line 10b of the base 1.
[0021]
FIG. 4A is a perspective view showing a surface-mounted antenna according to a third embodiment, and FIG. 4B is an expanded view thereof. In accordance with the second aspect of the present invention, a radiation electrode 21 formed on one main surface of the base 1 and a ground formed on the base 1 so as to be capacitively coupled to one end of the radiation electrode 21 at a distance. An electrode 3 is provided.
This embodiment is characterized by the radiation electrode 21 and the feed electrode 4. The radiation electrode 21 is provided mainly on the upper surface 1 c of the base 1, and extends continuously and / or stepwise from the one end connected to the ground electrode 3 to the other end in the longitudinal direction while substantially reducing the width. It comprises a portion 21a and a radiation electrode portion 21b bent in a U-shape or U-shape at the left end.
[0022]
With such a radiating electrode 21, broadband resonance characteristics can be obtained with the trapezoidal radiating electrode portion 21a, and inductance can be supplemented with the bent radiating electrode portion 21b.
The electrode 6 is a soldering electrode for fixing the surface-mounted antenna to the circuit board, and is provided in a necessary minimum.
A gap is provided between the outer periphery of the radiation electrode 21 and the ridge line of the base 1. This gap facilitates electrode printing and makes printing less likely to occur. In addition, electrode peeling due to deformation or chipping of the ridge portion of the base 1 can be prevented.
By preventing printing misalignment and electrode peeling, variations in center frequency can be suppressed. In the configuration in which the radiation electrode 21 is provided only on the upper surface 1c of the base 1, compared with the configuration in which the radiation electrode is also provided on the side surface, the capacitive coupling with the ground conductor of the circuit board is reduced, so that a high gain can be obtained.
[0023]
In the surface-mounted antenna 9 shown in FIG. 4, the gap is provided in parallel with three ridge lines 10 a to 10 c of the four ridge lines of the base 1.
Further, the corners of the radiation electrode 21 and the power supply electrode 4 are rounded to reduce the loss. For example, the corner between one side 22a and 22b of the radiation electrode and the corner between one side 22b and 22c of the radiation electrode are rounded.
[0024]
FIG. 5A is a perspective view showing a surface mount antenna according to a fourth embodiment, and FIG. 5B is an expanded view thereof. The power supply electrode 4 has a power supply end 43 at one end, an L-shaped electrode portion 41 provided on the side surface 1b, an I-shaped electrode portion 42 provided on the end surface 1f, and a grounded end 44 at one end. And an L-shaped electrode portion 45 provided at 1d.
The portal-type feeding electrode 4 has a U-shaped parallel portion 41 including electrode portions 41, 42, and 45 provided over two side surfaces 1b and 1d and an end surface 1f, and the parallel portion 41 is a U-shaped radiation electrode. 21b. With such a feeding electrode 4, capacitive coupling can be performed over substantially the entire U-shaped portion of the radiation electrode 21, which is advantageous in reducing the size of the surface-mounted antenna. In addition, for the same capacitance value, the distance between the radiation electrode 21 and the radiation electrode 21 can be widened, and variation in the capacitance value and variation in the center frequency due to printing deviation or the like can be reduced.
[0025]
In the surface-mounted antenna 9 shown in FIG. 5, as in the second embodiment shown in FIG. 4, the gap is provided in parallel with three ridge lines 10a to 10c among the four ridge lines of the base 1.
[0026]
FIG. 6A is a perspective view showing a surface mount antenna according to a fifth embodiment, and FIG. 6B is a developed view thereof. The band-shaped radiation electrode 21 includes a crankshaft-shaped electrode portion 21d formed on the side surface 1d in the longitudinal direction and an L-shaped electrode portion 21c formed on the upper surface 1c. is there. As described above, since the radiation electrode 21 extends in a bent shape from the upper surface to the side surface of the base 1, the overall length can be increased. As a result, the dimensions of the surface mount antenna base 1 can be reduced for the same bandwidth.
The positional relationship between the power supply portion 43 and the grounding portion 44 of the power supply electrode 4 is opposite to that in the above-described embodiment, and the power supply point 40 is located substantially in the center of the base, and the power supply portion 43 is located near the open end of the radiation electrode 21. I am trying to do it. Further, when the L-shaped electrode portion 21c formed on the upper surface 1 is projected on the lower surface, it does not overlap with the ground electrode 3.
As a result, the bandwidth is improved, the omnidirectionality is good, and the surface mount antenna for GPS is well balanced.
The open end of the radiation electrode 21 and the parallel portion 41 of the feed electrode 4 are close to each other. The wide parallel portion 41 facilitates impedance matching and slightly improves the gain.
[0027]
In the present embodiment, the parallel portion 41 has a wide and nearly rectangular shape, but the shape of the power supply electrode 4 can be variously changed depending on the mounting position on the circuit board side, the arrangement of the conductor pattern, the radiation electrode structure, and the like. .
Even if the specifications of the circuit board and the radiation electrode 21 are changed, the inductance, the capacitance and the like can be appropriately adjusted by appropriately setting the arrangement, shape, size, and the like of the power supply electrode 4 between the power supply point 40 and the ground point 42. The impedance can be easily adjusted by adjusting.
[0028]
FIG. 7A is a perspective view showing a surface mount antenna according to a fourth embodiment, and FIG. 7B is an expanded view thereof. In this example, the configuration of the power supply electrode 4 is different from those of the other examples. That is, the power supply electrode 4 includes an F-shaped electrode portion 41 having a power supply end 43 and a ground end 44 provided on the side surface 1b of the base 1 and linear electrode portions 42 and 45 formed on the end surface 1f and the side surface 1d. Become. The power supply electrode of this embodiment can achieve a wide band using multiple resonance simultaneously with impedance matching.
[0029]
It should be noted that the present invention is not limited to the configuration of the surface mount antenna illustrated in each of the above embodiments, and it is possible to combine them, and various other embodiments are configured within the scope of the present invention. I can do it.
[0030]
In the surface-mounted antenna according to the present invention, the base 1 is not limited to a rectangular parallelepiped but has an appropriate shape. The material may be a magnetic body, a resin body, or a laminated substrate thereof. Also, it is effective to trim the parallel portion or the base formed at the open end of the ridge of the radiation electrode for widening the bandwidth or adjusting the frequency.
[0031]
The radiation electrode 2 may have various shapes such as a trapezoidal shape, a stepped shape, a curved shape, a meander shape, a partial meander shape, and a crank shape.
Further, it is not always necessary to form a ground electrode continuously on one end side of the radiation electrode 2, and it is sufficient that the ground electrode can be finally grounded without any discontinuous capacitive coupling.
In addition, the ground electrode only needs to cover at least its end face and be connected to the ground plane so that it can be grounded. However, in order to obtain the effect of suppressing the emission of electric field from the end face of the base body, the end face and its end face are required at the base end. It is good to form so that the surrounding four sides may be covered.
[0032]
When a dielectric is used as the substrate 1 in the present invention, the relative dielectric constant εr is preferably in the range of 6 to 50. The relative permittivity εr is determined in consideration of the temperature coefficient of the dielectric, the processing accuracy of the substrate, and the like. However, if the material, processing accuracy, and the like are improved, the upper limit value is naturally increased. A substrate having such a relative dielectric constant εr is, for example, a body composed of raw materials of 22.22% by weight of MgO, 63% by weight of CaCO3, 48.14% by weight of TiO2, and 24.6% by weight of ZnO. It can be formed by firing and using a dielectric ceramic (relative dielectric constant εr: 21) composed of 36.6 mol% MgO, 3.4 mol% CaO, 40 mol% TiO2, and 20 mol% ZnO as a firing substrate. it can.
[0033]
In the present invention, even if chamfering is performed on the ridge portion of the base, the performance of the surface mount antenna does not change, and cracks, chipping, and the like are less likely to occur at the ridge of the base chip due to handling of an automatic assembly line of a mobile phone. Can also be expected. Further, in the surface-mounted antenna according to the present invention, at least one side of the radiation electrode 2 and the ridge lines 10a to 10h of the base body 1 are arranged with a predetermined gap formed therebetween. The effect of reducing the influence of reliability deterioration due to cracks can also be expected.
[0034]
【The invention's effect】
According to the present invention, it is possible to provide a surface-mounted antenna in which the variation of the center frequency is suppressed even when the printing displacement of the electrode pattern occurs, and the trouble of frequency adjustment is reduced. In addition, a surface-mounted antenna that is small and lightweight, has high radiation efficiency, has a wide band, and has no directivity can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view of a surface mount antenna according to a first embodiment of the present invention.
In the surface mount antenna of the present invention; FIG, characteristic curve indicating a shift amount Delta] f 0 of the ratio d / W and the center frequency f ₀ of the width W of the gap d and the _substrate, the normalized bandwidth, a relationship between radiation efficiency FIG.
FIG. 3A is a perspective view of a surface mount antenna according to a second embodiment of the present invention, and FIG. 3B is a developed view thereof.
FIG. 4A is a perspective view of a surface mount antenna according to a third embodiment of the present invention, and FIG. 4B is a developed view thereof.
FIG. 5A is a perspective view of a surface mount antenna according to a fourth embodiment of the present invention, and FIG. 5B is a developed view thereof.
FIG. 6A is a perspective view of a surface mount antenna according to a fifth embodiment of the present invention, and FIG. 6B is a developed view thereof.
FIG. 7A is a perspective view of a surface mount antenna according to a sixth embodiment of the present invention, and FIG. 7B is a developed view thereof.
FIG. 8 is a perspective view showing an example of a conventional surface mount antenna.
FIG. 9 is a perspective view showing another example of a conventional surface mount antenna.
[Explanation of symbols]
1: bases 10a to 10h: ridge line 2 of base 1: radiation electrode 20: open end 21 of radiation electrode 2: radiation electrodes 22a to 22h: one side of radiation electrode 3: ground electrode 4: feeding electrode 40: feeding point 41: feeding. Parallel part 42 of electrode 4: ground point 43: leg part serving as a power supply end (power supply part)
44: Leg to be the grounding end (grounding part)
6: Fixing electrodes 71, 72: Short-circuit conductor 9: Surface mount antenna

Claims (2)

A substrate made of a dielectric or magnetic material;
A radiation electrode formed on at least one surface of the substrate,
A ground electrode formed on the base by directly connecting to one end of the radiation electrode;
A surface-mounted antenna having a feed electrode spaced apart from and facing the radiation electrode,
At least one side of the radiation electrode and a ridge line of the base form a gap,
A surface-mounted antenna, wherein the ratio of the gap to the width of the base is 0.05 to 0.2. A substrate made of a dielectric or magnetic material;
A radiation electrode formed on at least one surface of the substrate,
A ground electrode formed on the base so as to be capacitively coupled to one end of the radiation electrode;
A surface-mounted antenna having a feed electrode spaced apart from and facing the radiation electrode,
At least one side of the radiation electrode and a ridge line of the base form a gap,
A surface-mounted antenna, wherein the ratio of the gap to the width of the base is 0.05 to 0.2.

Images