KR200220784Y1 - A wideband helical antenna with dual coil - Google Patents

Abstract

The present invention relates to a helical antenna used in various mobile communication terminals, and more particularly, to a wideband helical antenna using a double coil configured to have a wide band characteristic by configuring two coils in a double.

Conventional helical antennas have a wide band characteristic by using a single wide band matching circuit to a single pitch coil to expand the bandwidth, or by configuring a single pitch of a coil to have a wide band characteristic. Helical antennas have a problem in that the structure is complicated and the design is not easy.

Accordingly, the present invention has been made to solve the above problems, the first radiator having a length of 1/4 wavelength electrically for the first frequency; and has a length of 1/4 wavelength for the second frequency electrically A second copy wound in a rotational direction opposite to a rotational direction of the first copy, the second copy being concentric with the first copy and inserted into the first copy; and the first copy for feeding the first copy and the second copy And a feeding means provided at a lower end of the second copy and electrically connected to an internal feeding circuit of the terminal. And a cover that protects the first copy and the second copy from an external environment.

Therefore, the wideband helical antenna using the double coil according to the present invention has a simple configuration and has the effect of improving mass production and reliability of the product.

Description

A wideband helical antenna with dual coil

The present invention relates to a helical antenna used in various mobile communication terminals, and more particularly, to a wideband helical antenna using a double coil configured to have a wide band characteristic by configuring two coils in a double.

Antennas that are conventionally used in various mobile communication terminals can be classified into a combination of a helical antenna and a monopole antenna, and a type using only a fixed helical antenna. The former can be divided into two types. One is a helical antenna mounted on the top of the terminal housing and penetrated therein, and a monopole antenna is inserted and used as a stretchable type, and the other is a monopole antenna. Helical antenna is mounted on the top to be used as a flexible type.

However, these types of antennas for terminals have a narrow bandwidth, so that broadband systems such as International Mobile Telecommunication (IMT-2000), which will be serviced in the future, or existing cellular cellular (DCS) bands and personal mobile phones are available. There is a problem in that it is difficult to apply to a multi-band system such as including a personal communication service (PCS) band.

Therefore, to solve this problem, the helical antenna is configured with a single pitch and a bandwidth is expanded by using a separate broadband matching circuit, or one coil is configured with a different pitch to have a broadband characteristic. However, this type of helical antenna has another problem that its structure is complicated and its design is not easy. For example, in one frequency band, there is a certain radiation efficiency and gain, but in another frequency band, the efficiency decreases and the gain falls.

The present invention was devised to overcome the above problems, and a wideband helical antenna using dual coils having dual characteristics of two coils having different resonance frequencies and opposite rotation directions and simultaneously feeding power has a wide band characteristic. It is a technical task to provide.

1 is an exploded perspective view showing an embodiment of a wideband helical antenna using a double coil according to the present invention.

Figure 2 is an assembled state of the embodiment of Figure 1 assembled.

3 is a reflection loss characteristic diagram according to the frequency of the embodiment of FIG.

Figure 4 is an exploded perspective view showing another embodiment of a wideband helical antenna using a double coil according to the present invention.

5 is a reflection loss characteristic diagram according to the frequency of the embodiment of FIG.

※ Explanation of codes for main parts of drawing

101. Feed conductor 101a. Thread

101b. Flange 101c. edge

101d. Home 101e. Jam

101f. Sleeve 102. Outer Bobbin

103, 301. First stripline 104. Internal bobbin

105. Second stripline 106. Annular stripline

107. Inner bobbin sleeve 201. Cover

In order to solve the above technical problem, a wideband helical antenna using a dual coil according to the present invention has a spiral first radiator electrically having a length of 1/4 wavelength for a first frequency; and 1 / for a second frequency. A spiral second copy having a length of 4 wavelengths and wound in a rotational direction opposite to the rotational direction of the first copy, the second copy being inserted to have a concentric axis inside the first copy; and the first copy and the second copy A feed conductor provided at a lower end of the first radiator and the second radiator to be fed at the same time and electrically connected to an internal feed circuit of the terminal; And a cover that protects the first copy and the second copy from an external environment.

Hereinafter, a preferred embodiment of a broadband helical antenna using a double coil according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or corresponding members will be denoted by the same reference numerals and detailed description thereof will be omitted.

1 is an exploded perspective view showing an embodiment of a wideband helical antenna using a double coil according to the present invention, the input signal input through the feed conductor 101 from the terminal internal power supply circuit (not shown) is an external bobbin (bobbin) The first stripline 103 formed on the 102 and the second stripline 105 formed on the inner bobbin 104 are simultaneously fed to the outer space.

The first strip line 103 formed on the outer circumferential surface of the cylindrical outer bobbin 102 is formed by dividing a groove in the outer circumferential surface and plating a conductive strip using equipment such as a milling lathe. Its diameter, pitch, and number of revolutions are determined to have a quarter-wavelength for one frequency.

The cylindrical outer bobbin 102 has an empty shape so that the inner bobbin 104 can be accommodated, and the diameter of the cylindrical outer bobbin 102 in consideration of the bobbin surface treatment performed after the plating operation, the first It is desirable to be slightly larger than the diameter of the stripline 103. The material is selected in consideration of permittivity and ease of processing. In this embodiment, a polycarbonate series is used.

In addition, an annular conductive strip 106 is also plated on the upper surface of the outer bobbin 102, which applies the prior art in which radiation efficiency is improved by bending the upper end of the coil slightly inward.

Although not shown, it is preferable that a conductive strip is plated on the bottom of the outer bobbin, so that an electrically reliable connection can be made when it is closely connected to the flange 101b of the feed conductor 101. to be.

The second stripline 105, whose diameter, pitch, and rotational speed are determined so as to have a length of 1/4 wavelength relative to the second frequency, is formed by the first stripline 103. The spiral direction of rotation is the same as that of the first stripline. The internal bobbin 104 is inserted into the empty space of the external bobbin 102 and the first strip line 103 and the second strip line 105 formed on the outer circumferential surface thereof are fed from the power supply circuit in the terminal to signal In order to minimize the reduction of the radiation efficiency due to the mutual coupling (mutual coupling) occurring between the two strip lines (103, 105). In more detail, the coils are formed in opposite directions to offset the electromagnetic field components that cause mutual interference so that the broadband characteristics can be obtained.

Unlike the cylindrical outer bobbin 102, the inner bobbin 104 in which the second stripline 105 is formed has a cylindrical shape, and its diameter is the same as the inner diameter of the outer bobbin 102, but in manufacturing Somewhat larger is preferred for the same reasons as for the external bobbin 102. The material used in this embodiment, such as the external bobbin 102 in consideration of the dielectric constant and the ease of processing.

In addition, unlike the outer bobbin 102, the inner bobbin sleeve 102 is formed to extend in the lower portion of the inner bobbin 104, which is inserted into the groove 101d formed in the feed conductor 101 to be inserted into the inner bobbin. In order to stabilize the characteristics of the antenna by supporting and fixing the 104, a conductive material extends from the second strip line 105 and plated on the outer circumferential surface thereof to ensure electrical connection with the feed conductor 101. It is to let.

The cylindrical feed conductor 101 having a thread 101a at the bottom and a flange 101b at the top is connected to one side of a housing electrically connected to a feed circuit (not shown) in the terminal. The first strip line 103 and the second strip line 105 are contacted and connected to each other through a flange 101b formed at an upper end thereof.

The disc-shaped flange 101b has an edge 101c formed at an outer side thereof to fix and support the outer bobbin 102 so as to stabilize the radiation characteristics of the first strip line 103 formed on the outer circumferential surface thereof. Inwardly, it has a groove 101d of a predetermined depth to accommodate the inner bobbin sleeve 107.

In the middle of the cylindrical sleeve 101f, the hooking jaw 101e is enclosed in an annular shape. The outer bobbin 102 closely adheres to the feed conductor flange 101b through a cover 201 that protects the antenna from the external environment. To be connected.

2 is an assembled state diagram of the embodiment of FIG. By inserting the inner bobbin sleeve 107 into the groove 101d formed inside the upper flange of the feed conductor 101, the lower end of the second strip line 105 formed on the outer circumferential surface of the inner bobbin is the flange It is electrically connected to a power supply circuit in the terminal via 101b.

The outer bobbin 102 is tightly connected to the flange 101b while the inner bobbin 104 is accommodated in an empty space formed therein. At this time, the edge 101c formed by the outer shell of the flange serves to allow the external bobbin to be in close contact with and connected to the flange. Thus, the first strip line 103 formed on the outer circumferential surface of the outer bobbin is electrically connected to the power supply circuit in the terminal through the flange 101b.

The cover 201 that protects the first and second strip lines 103 and 105 from an external environment has the first and second bobbins 102 and 104 in close contact with the flange 101b and formed on the outer circumferential surface thereof. The lower end of the strip line 103 and the lower end of the second strip line 105 are forcibly fitted to the latching jaw 101e so as to be securely connected to the feed conductor 101.

3 shows the return loss characteristic according to the frequency of the embodiment of FIG. In FIG. 3, the horizontal axis represents a frequency range (unit: MHz) and the vertical axis represents a reflection loss (unit: dB). In general, a voltage standing wave ratio (VSWR) required by an antenna used in a mobile communication terminal is about 1.9, which is about -10 dB when converted into return loss by Equation 1 below. Therefore, it has a broadband characteristic of about 400 MHz (1.78 GHz to 2.18 GHz) usable in the frequency band of personal mobile communication (PCS) and the next generation mobile communication (IMT-2000) on the basis of the return loss of -10 dB. Able to know.

For reference, the diameter of the external bobbin used for the measurement in Figure 1 of the embodiment of the present invention is 5mm, pitch is 2mm, the number of revolutions is 8 times, the diameter of the inner bobbin is 3.2mm, pitch is 1.5mm, the number of revolutions It was 12 times.

4 is an exploded perspective view showing another embodiment of the present invention. The difference from the embodiment of FIG. 1 is that the pitch of the first stripline 301 formed on the outer circumferential surface of the outer bobbin is a double pitch. Since the double pitch can be seen as the addition of an antenna having a longer electrical length to the embodiment of FIG. 1, another resonance band of a lower frequency can be formed in addition to the resonance band of the embodiment of FIG.

5 shows the return loss according to the frequency of the embodiment of FIG. As shown, it can be seen that due to the influence of the double pitch 301 formed on the outer circumferential surface of the external bobbin, it has a multi-band resonance characteristic that double resonates in the frequency bands used by the cellular mobile telephone (DCS) and the personal mobile communication (PCS).

As described above, the wideband helical antenna using the double coil according to the present invention is composed of only two coils, which simplifies the configuration, thereby improving mass productivity, increasing reliability of the product, and having broadband or multiband resonance characteristics. Has

Claims (3)

A helical first radiator having a length of quarter wavelength electrically for the first frequency; A helical second radiator having a length of 1/4 wavelength with respect to a second frequency and wound in a rotational direction opposite to the rotational direction of the first radiator and inserted into the first radiator; A feed conductor provided at a lower end of the first radiator and the second radiator to electrically feed the first radiator and the second radiator simultaneously and electrically connected to an internal power supply circuit of the terminal; And Broadband helical antenna using a double coil comprising a cover for protecting the first radiator and the second radiator from an external environment. The method of claim 1, The first copy is, Its internal hollow has a cylindrical shape, the outer bobbin of the dielectric material having a spiral groove in the outer peripheral surface (bobbin); and It is formed by inserting into the spiral groove of the outer bobbin, consisting of a first electrically conductive stripline having a length of 1/4 wavelength relative to the first frequency, The second copy, An inner bobbin of a dielectric material inserted into an inner space of the outer bobbin, having a cylindrical shape, and having a spiral groove recessed in an outer circumferential surface thereof; An inner bobbin sleeve which is formed extending from a lower portion of the inner bobbin and whose surface is plated; and Broadband helical antenna using a double coil is formed by inserting into the spiral groove of the internal bobbin, and electrically conductive second stripline having a length of 1/4 wavelength with respect to the second frequency. The method of claim 2, The feed conductor, A flange of a metal material having a circular flat plate shape, which is in close contact with and is electrically connected to a lower end of the first strip line and a lower end of the second strip line; A rim which protrudes to the outer edge of the flange and is formed in a circular shape, and wherein the outer bobbin on which the first stripline is formed is closely attached to and contacted with the flange; A groove formed in the center of the flange to receive the inner bobbin sleeve inwardly; A cylindrical sleeve made of metal extending from the flange; A catching jaw formed annularly around the outer circumferential surface of the sleeve; And Broadband helical antenna using a dual coil, characterized in that consisting of a screw thread formed on the lower outer peripheral surface of the sleeve to be fastened to the terminal housing.