KR100742098B1 - Antenna using slit skirt - Google Patents

Abstract

An antenna using a slit skirt is provided to maximize a moving effect to a low frequency by inserting a dielectric between the slit skirts. An antenna includes a first radiator(21), a second radiator(22), an empty space(41), a feeding unit, a first slit skirt(42), and a second slit skirt(43). The first radiator(21) is formed in a conductive pattern on an upper surface of a dielectric substrate. The second radiator(22) is connected with the first radiator(21) on the upper surface of the dielectric substrate, and is formed with a slit occupying a predetermined space at one side of a space in which the first radiator(21) is formed. The empty space(41) is formed by removing a part of the dielectric substrate area, which is occupied by the slit. The feeding unit is connected with one end of the first radiator(21) or the second radiator(22), and feeds the first radiator(21) and the second radiator(22). The first slit skirt(42) is extended from the first radiator(21) by dropping a slit skirt in the empty space(41). The second slit skirt(43) is extended from the second radiator(22) by dropping a slit skirt in the empty space(41).

Description

Antenna using Slit Skirt}

1 is a structural diagram of a typical PIFA antenna.

2 is a structural diagram of a general planar inverted-F antenna being developed and applied by the applicant.

3 is a side view of the PIFA shown in FIG.

4 is a structural diagram of a modified planar inverted-F antenna according to the present invention.

FIG. 5 is a side view of the PIFA shown in FIG. 4. FIG.

6 is a structural diagram of a planar inverted F antenna according to another embodiment of the present invention.

FIG. 7 is a side view of the PIFA shown in FIG. 6.

FIG. 8A is a graph of reflection coefficient results simulating the general PIFA structure of FIG. 2. FIG.

8B is a built-in antenna designed using a simulation program.

FIG. 8C is a graph showing simulation results of varying the length L1 of the first slit _ skirt 42 of the first radiator 21.

FIG. 8D is a graph showing simulation results of varying the length L2 of the second slit skirt 2 of the second radiator 22.

FIG. 8E is a graph of simulation results by simultaneously varying the lengths L1 and L2 of the first slit_skirt 42 and the second slit_skirt 43.

FIG. 8F shows a dielectric 61 inserted between the first slit skirt 42 and the second slit skirt 43, the first slit skirt 42, the second slit skirt 43 and the dielectric ( 61) Simultaneously vary the length of the graph is the result of the simulation.

9A to 9E are graphs of reflection coefficients measured by a network analyzer R3765CG manufactured by ADVANTEST, for a slit_skirt antenna manufactured according to the present invention.

9A is a reflection coefficient graph of a general PIFA described with reference to FIG. 2.

9B and 9C are graphs of the measurement results of a single application of the slit skirts 42 and 43 having a width of 10 mm and a length of 3 mm to the first radiator 21 and the second radiator 22, respectively.

FIG. 9D is a graph showing results obtained by simultaneously applying the slit skirts 42 and 43 to the first radiator 21 and the second radiator 22.

FIG. 9E is a graph showing the results obtained by inserting a dielectric 61 between the slit skirts 42 and 43 of the first radiator 21 and the second radiator 22.

10A to 10D show slits_skirts 42 and 43 respectively applied to the first radiator 21 and the second radiator 22, and each GSM900 (FIG. 10A) of an antenna having a dielectric 61 inserted therebetween. , DCS1800 (FIG. 10B), DCS1900 (FIG. 10C), and WCDMA band (FIG. 10D) are graphs showing 3D gain measurement results.

The present invention relates to an antenna structure, and more particularly, to an antenna for maximizing the efficiency of an antenna used as an antenna, such as a mobile communication terminal, a DMB terminal, a vehicle frequency antenna, a vehicle electronic key, and an RFID port antenna.

In the embodiments of the present invention, for convenience of description, the built-in planar inverted F antenna is described as an example. All antenna structures included are included.

At present, a variety of service providing functions are required while the mobile communication terminal and the DMB terminal are smaller and lighter. In order to satisfy these demands, embedded circuits and components employed in mobile communication terminals are gradually miniaturized, and antenna-related components are also miniaturized or embedded.

In general, antennas used in mobile terminals include a helical antenna and a planar inverted F antenna (hereinafter referred to as PIFA). The helical antenna is an external antenna fixed to the top of the terminal and used together with the monopole antenna. When the helical antenna and the monopole antenna are used together, the antenna is operated as a monopole antenna when the antenna is extended from the main body of the terminal, and when the antenna is extended, the antenna is operated as a λ / 4 helical antenna.

These antennas have the advantage of obtaining high gain, but due to their omni-directional, SAR characteristics, which are harmful to the human body of electromagnetic waves, are not good. In addition, since the helical antenna is configured to protrude outside the terminal, it is difficult to design an exterior suitable for the aesthetic appearance and the portable function of the terminal. Since the monopole antenna also needs to provide a sufficient space for its length inside the terminal, there is a problem in that the product design for miniaturization of the terminal is limited.

To overcome this disadvantage, there is a planar inverted F antenna (PIFA) having a low profile structure.

1 is a structural diagram of a typical PIFA antenna.

PIFA is an antenna that can be embedded in a mobile terminal, as shown in FIG. 1, basically a planar radiator 1, a shorting pin 3 connected to the radiator 1, a coaxial line 5, and a ground. It consists of the board 7. The radiator 1 is fed through the coaxial line 5, and is short-circuited with the ground plate 7 by the short circuit pin 3 to achieve impedance matching. The PIFA should be designed considering the length L of the radiator 2 and the height H of the antenna according to the width Wp of the shorting pin 3 and the width W of the radiator 1.

On the other hand, since the PIFA has a limited antenna volume, it is difficult to realize a low frequency band only by the area and length configurable therein. Therefore, there is a need for an improved planar inverse F antenna that can solve this problem and implement a low frequency band within the limited space of the antenna.

An object of the present invention is to implement an antenna capable of realizing a low frequency band by maximizing the limited space of the antenna and the efficiency of the antenna in a planar inverted F antenna (PIFA), which must be limited in area and length do.

In order to achieve the object of the present invention as described above, according to a feature of the present invention, a slit skirt antenna is connected to the first radiator formed in a conductive pattern on the upper surface of the dielectric substrate, the first radiator on one side of the dielectric substrate upper surface And a second radiator formed with a slit occupying a predetermined space on one side of the space where the first radiator is formed, an empty space formed by removing a portion of the dielectric substrate region occupied by the slit, the first radiator or the first agent. 2 a feeder connected to one end of the radiator and connected to feed the first radiator and the second radiator, a first slit_skirt formed by lowering a slit_skirt in the empty space and extending from the first radiator, and the bin And a second slit_skirt formed by lowering the slit_skirt into the space and extending from the second radiator.

In this case, the first radiator and the second radiator form a resonant frequency of a dual band by using the current flowing into the respective, and by the electromagnetic coupling between the first slit skirt and the second slit skirt Move the resonant frequency to the low frequency band.

Preferably, the first slit skirt and the second slit skirt are formed to face each other in parallel. The amount of movement to the low frequency band may be adjusted by adjusting the capacitance value by the coupling between the first slit skirt and the second slit skirt. In addition, the capacitance value may be adjusted by adjusting the length in the vertical direction of the first slit skirt and the second slit skirt.

More preferably, between the first slit skirt and the second slit skirt is filled with a dielectric.

The slit skirt antenna may be a multi-resonance built-in antenna, specifically a planar inverted F antenna. In this case, the first radiator is formed to be bent in a parallel direction along the circumference of the second radiator so as to surround the second radiator with a quadrangle having one side with the slit therebetween.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

2 is a structural diagram of a general planar inverted-F antenna being developed and applied by the applicant.

Referring to FIG. 2, a planar inverted F antenna 20 is formed on an upper surface of a dielectric substrate, and a first radiator 21 and a second radiator 22 constituting a radiator are formed with a single pass.

The first radiator 21 has a length sufficient to resonate with the frequency of the low frequency band by the slit 24 on the upper surface of the dielectric, the second radiator 22 is the first radiator with the slit 24 in between One side of the space in which the 21 is formed is formed to extend in parallel with the first radiator 21.

Meanwhile, the slit 24 may be formed by partially removing the inside of the first radiator 21. In addition, the shapes of the first radiator 21, the second radiator 22, and the slit 24 may be modified according to the grounding and radiating characteristics of the PIFA 20. In addition, the first radiator 21 and the second radiator 22 are electrically connected directly through the connecting portion 26. The connecting portion 26 is formed of a conductor.

The power supply unit 25 connects the first radiator 21 and the second radiator 22 and a power supply unit (not shown) to supply current to the first radiator 21 and the second radiator 22, and a ground part. 23 functions to ground the first radiator 21 and the second radiator 22.

3 is a side view of the PIFA shown in FIG.

Referring to FIG. 3, it can be seen that the first radiator 21, the second radiator 22, the slit 24, the ground 23, and the power supply 25 are formed on the dielectric substrate 31.

However, with the structure of the conventional PIFA shown in FIG. 2, a mobile small antenna capable of using DMB or a vehicle frequency, which is recently important, cannot be implemented.

4 is a structural diagram of a modified planar inverted-F antenna according to the present invention.

Referring to FIG. 4, the PIFA 40 according to the present invention removes a part of the space in which the slit 24 exists between the first radiator 21 and the second radiator 22 to create an empty space 41. In the meantime, a first slit_skirt 42 that is an extension of the first radiator 21 and a second slit_skirt 43 that is an extension of the second radiator 22 are formed.

Since the first slit _ skirt 42 and the second slit _ skirt 43 operate as stubs for extending the electrical length of the first radiator 21 and the second radiator 22, respectively, The resonance frequency of each of the second radiators 22 is moved to the low frequency band. Furthermore, due to the shape of the first slit skirt 42 and the second slit skirt 43 facing each other closely, the capacitance component generated between the slit skirts 42 and 43 is not limited to the first radiator 21 and the first radiator 21. In addition to lowering the resonance frequency of each of the two radiators 22, the bandwidth of each resonance band is extended.

One way to control the shift to the low frequency band may be achieved by adjusting capacitance due to mutual coupling between the slit_skirts, which is the distance between the slit_skirts, or the slit_. The shift in the low frequency band can be controlled by adjusting the width of the skirts and the vertical length of the slit skirt.

FIG. 5 is a side view of the PIFA shown in FIG. 4. FIG.

Referring to FIG. 5, the PIFA 40 according to the exemplary embodiment of the present invention moves the resonance at a low frequency in a shape in which the first slit_skirt 42 and the second slit_skirt 43 face each other. In addition, the amount of movement can be adjusted by changing the capacitance value by adjusting the lengths L1 and L2 of the first slit_skirt 42 and the second slit_skirt 43.

If the lengths L1 and L2 of the first slit skirt 42 and the second slit skirt 43 are small, the capacitance is small, so that the amount of movement to low frequency is small and the lengths of the slit skirts L1 and L2 are long. The larger the amount, the greater the amount of movement to the low frequency.

6 is a structural diagram of a planar inverted F antenna according to another embodiment of the present invention.

Referring to FIG. 6, the PIFA 60 according to another embodiment of the present invention has an empty space in which the slit 24 is removed between the first radiator 21 and the second radiator 22 of the PIFA 40 of FIG. 4. The dielectric 61 is inserted into the 41.

In the PIFA 60 according to another embodiment of the present invention, a dielectric 61 is inserted between the first slit skirt 2 and the second slit skirt 43 to maximize the coupling effect between the two slit skirts. Let's do it. Accordingly, in the case of the PIFA 60 shown in FIG. 6, it is possible to enhance the shift of the resonance frequency to the low frequency band by increasing the capacitance due to the insertion of the dielectric 61.

Even in this case, the slit skirts 42, 43 through adjustment of the distance between the slit skirts, or the width of the slit skirts, the vertical length of the slit skirts, or the use of a dielectric having a different dielectric constant. It is possible to adjust the capacitance due to the mutual coupling between the and the low frequency band.

FIG. 7 is a side view of the PIFA shown in FIG. 6.

Referring to FIG. 7, in the PIFA 60, a dielectric 61 is inserted between the first slit skirt 2 and the second slit skirt 43.

Hereinafter, the simulation experiment results for the characteristics of the slit skirt antenna according to the present invention will be introduced. The simulation program was CST Microwave Studio 5.1.

8A is a reflection coefficient result of simulating the general PIFA structure of FIG. 2. The following description of the graph of FIG. 8A refers to FIG. 2. In this case, the size of the ground plane to which the PIFA is connected was 68 × 40 × 1 mm, similar to a general mobile phone, and a radiator was formed on the dielectric substrate 31 (ε _r = 3.5). The size of the dielectric substrate 31 is 40 × 21 mm and the height is 6 mm. 8B is a built-in antenna designed using a simulation program according to the above conditions. The frequency band is designed to satisfy four service bands used in Europe: GSM900 (800 ~ 960MHz), DCS1800 (1710 ~ 1880MHz), DCS1900 (1850 ~ 1990MHz), and WCDMA (1920 ~ 2170MHz). As a result, an antenna resonating in the 950 MHz band and the 2,200 MHz band has been implemented. The bandwidths were 43MHz and 290MHz, respectively, with a return loss of -6 dB.

8C to 8E are graphs showing simulation results of the characteristics of the PIFA described with reference to FIG. 4 as the slit skirt antenna according to the present invention. The following description of the graph of FIGS. 8C-8E refers to FIG. 4.

FIG. 8C is a simulation result of varying the length L1 of the first slit_skirt 42 of the first radiator 21. FIG. 8D is a view of the second slit_skirt 43 of the second radiator 22. FIG. The simulation results are shown by varying the length L2. As a result of the simulation, the change of low frequency and high frequency characteristics is weak.

FIG. 8E shows a simulation result by simultaneously changing the lengths L1 and L2 of the first slit_skirt 42 and the second slit_skirt 43. As a result of the simulation, the resonant frequency of the low frequency band is moved about 150MHz to the low frequency band, but the amount of frequency shift is small, but the resonant frequency of the high frequency band is also moved to the low frequency band.

FIG. 8F is a graph showing a simulation experiment result for the characteristics of the PIFA described with reference to FIG. 6 as the slit skirt antenna according to the present invention. The following description of the graph of FIG. 8F refers to FIG. 6.

FIG. 8F shows a dielectric slit (epsilon _r = 3.5) is inserted between the first slit_skirt 42 and the second slit_skirt 43, the first slit_skirt 42, the second slit_skirt ( 43) and the length of the dielectric 61 are changed simultaneously, and the simulation result is shown. Simulation results show that the low frequency band is shifted to the 600MHz band and can be applied to the performance of low frequency band below 800MHz.

Hereinafter, experimental results on the characteristics of the slit skirt antenna manufactured according to the present invention will be introduced. Antenna characteristics were measured using ADVANTEST's Network Analyzer R3765CG.

FIG. 9A is a graph of reflection coefficient S ₁₁ of the general PIFA described with reference to FIG. 2. The low center frequency is 1086MHz, the bandwidth is 203MHz (18.7%) at S ₁₁ -6dB, the high frequency center frequency is 1569MHz, and the bandwidth is 739MHz (39.2%).

9B to 9D are graphs showing experimental results of the characteristics of the PIFA described with reference to FIG. 4 as the slit skirt antenna according to the present invention. The following description of the graphs of FIGS. 9B-9D refers to FIG. 4.

9B and 9C show the results obtained by applying the slit skirts 42 and 43 having a width of 10 mm and lengths of L1 and L2 to 3 mm to the first radiator 21 and the second radiator 22, respectively. As the electrical length of the radiators 21 and 22 is extended by the slit skirts 42 and 43 functioning as stubs, the resonance frequency shifting effect is observed, and the bandwidth of the high frequency band is increased by about 10%.

FIG. 9D is a result obtained by simultaneously applying the slit skirts 42 and 43 to the first radiator 21 and the second radiator 22. In the case of FIG. 9D, the resonant frequency shift is shown in the low frequency band by 178 MHz and the high frequency resonant band by 210 MHz in the low frequency resonant band than in FIGS. 9B and 9C, and the bandwidth of the high frequency band is increased by about 25%. This is because the slit skirts 42 and 43 not only function as stubs of the radiators 21 and 22, respectively, but also cause electromagnetic coupling between them. That is, the resonant frequency bands of the radiators 21 and 22 are further moved to the low frequency band, and even the broadband effect is exhibited.

FIG. 9E shows the measurement result of inserting the dielectric 61 between the slit skirts 42 and 43 of the first radiator 21 and the second radiator 22. The low frequency resonant band moved to the lower frequency band by 220MHz, the largest frequency shift occurred, and the high frequency band moved 147MHz. In addition, the bandwidth of the high frequency band is increased by about 10%.

Table 1 below shows the resonance frequency and the bandwidth change according to the length change of the slit_skirt of the antenna according to the present invention.

Resonant Frequency (Moving Frequency) [MHz] Bandwidth [MHz] L = 0 1086 1884 203 (18.7%) 739 (39.2%) L = 1 1008 (78) 1870 (14) 126 (12.6%) 938 (50.1%) L = 2 1067 (19) 1711 (173) 182 (17.1%) 844 (49.3%) L = 3 908 (178) 1674 (210) 103 (11.3%) 1076 (64.3%) L = 4 866 (220) 1737 (147) 110 (12.7%) 856 (49.5%)

10A to 10D show slit_skirts 42 and 43 respectively applied to the low frequency radiator 21 and the high frequency radiator 22, and respectively the GSM900 (FIG. 10A) and the DCS1800 of the antenna having the dielectric 61 inserted therebetween. Fig. 10B shows DCS1900 (Fig. 10C) and WCDMA band (Fig. 10D) 3D gain measurement results. As a result, it can be seen that the peak gain of the entire band has a high radiation efficiency of 1.16 to 3.21 dBi.

Table 2 below shows the band-specific peak gain and average gain of the slit skirt antenna according to the present invention prepared by inserting a dielectric.

Band Frequency [MHz] Peak gain [dBi] Average gain [dBi] GSM900 880 2.02 -3.33 960 1.16 -3.28 DCS1800 1710 2.71 -1.83 1880 2.51 -2.05 DCS1900 1850 2.40 -1.99 1990 3.21 -1.23 WCDMA 1920 3.01 -2.10 2170 2.83 -2.14

The slit_skirt antenna according to the present invention can solve the difficulty of implementing low frequency in a limited space when designing a mobile terminal embedded antenna. The antenna according to the present invention can obtain the effect of extending the electrical length by using the slit skirt between the low frequency band radiator and the high frequency band radiator. The capacitance component between the two slit skirts maximizes the effect of extending the electrical length and increases the bandwidth. The insertion of a dielectric between the slit skirts maximizes the resonant frequency shift into the low frequency band. . In particular, it is possible to implement an antenna of excellent performance in the low frequency band.

Therefore, the antenna according to the present invention receives a low frequency band 400MHz band vehicle electronic key, CDME in Eastern Europe, container management for 433MHz RFID port, 470MHz ~ 740MHz UHF band and DCS 1800, DCS 1900, UMTS A small antenna can be implemented.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the antenna structure according to the present invention, by forming a slit in the basic built-in antenna, the slit_skirt (skirt) between the slit to expand the area of the pattern and by using the capacitance component between the slit_skirt to move the resonance to a low frequency and band Secure wide. In particular, by inserting a dielectric between the slit skirt can maximize the effect of moving to low frequencies.

By using the antenna incorporating the slit_skirt according to the present invention, the antenna size can be greatly reduced and a wideband effect can be obtained. In addition, by applying the slit skirt antenna to a slim mobile terminal, it is possible to manufacture an antenna that can easily implement low frequency band resonance in a less space.

Claims (9)

A first radiator formed on a top surface of the dielectric substrate in a conductive pattern; A second radiator connected to one side of the first radiator on an upper surface of the dielectric substrate and formed with a slit occupying a predetermined space on one side of a space in which the first radiator is formed; An empty space formed by removing a portion of the dielectric substrate region occupied by the slit; A feeder connected to one end of the first radiator or the second radiator to be connected to feed the first radiator and the second radiator; A first slit _ skirt formed by extending a slit _ skirt into the empty space and extending from the first radiator; And A slit skirt antenna comprising: a second slit_skirt formed by lowering a slit_skirt into the empty space and extending from the second radiator. The method of claim 1, The first radiator and the second radiator form a resonant frequency of a dual band by using currents flowing into the respective radiators, and the resonance frequency is caused by electromagnetic coupling between the first slit skirt and the second slit skirt. The slit skirt antenna which moved to low frequency band. The method of claim 1, And the first slit skirt and the second slit skirt are formed to face each other in parallel. The method of claim 2, The amount of movement to the low frequency band is controlled by adjusting the capacitance value by the coupling between the first slit skirt and the second slit skirt. The method of claim 4, wherein The capacitance value is adjusted by the length adjustment in the vertical direction of the first slit skirt and the second slit skirt. The method of claim 1, The slit skirt antenna is a slit skirt antenna is a multi-resonance built-in antenna. The method of claim 6, And the slit skirt antenna is a planar inverted F antenna. The method of claim 7, wherein And the first radiator is bent in a parallel direction along the circumference of the second radiator to surround the second radiator in a quadrangle with one side between the slits. The method according to any one of claims 1 to 8, A slit skirt antenna filled with a dielectric between the first slit skirt and the second slit skirt.

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