KR20030054845A - Wideband Printed Dipole Antenna - Google Patents

Abstract

PURPOSE: A broadband print-type dipole antenna is provided to be capable of transmitting and receiving an electro magnetic signal over a broadband by providing a broadband design guide of a dipole antenna. CONSTITUTION: A broadband print-type dipole antenna has a power feeder, is placed on a dielectric substrate, and transmits and receives an electro magnetic signal over a broadband. A ratio of a length(L) to a width(W) of each arm of a print-type dipole(100) is equal to or more than 0.9 or equal to or less than 1.1. A gap(G) between dipole arms is 0.1L. The print-type dipole is disposed on one surface of the dielectric substrate(110). A reflection part(310) is spaced apart from the dielectric substrate and is connected to a ground to form a radiation pattern of one direction. Baluns(320,330) are disposed between the dipole and the reflection part and feeds a current to the dipole.

Description

Wideband Printed Dipole Antenna

The present invention relates to a wideband printed dipole antenna, and more particularly, to a wideband printed dipole antenna capable of transmitting and receiving electromagnetic signals over a wide band in mobile communication and wireless communication systems.

With the development of mobile communication and wireless communication, there is an increasing demand for an antenna having a very wide bandwidth that can be used in multimedia communication, software defined radio (SDR), ultra wideband (UWB) communication, and the like. The wideband antenna as described above can cover various wireless services such as PCS (Personal Communication Service), IMT-2000 (International Mobile Telecommunication 2000), Bluetooth, etc. with one antenna, which is advantageous in terms of cost and space efficiency. It can be said that

Among the various antennas used in mobile communication and wireless communication, printed antennas are light and inexpensive, have mass production, and are easy to integrate with other high frequency circuits. In particular, printed dipole antennas offer much wider bandwidth than microstrip antennas, less excitation of surface waves, and less spurious radiation from feed lines.

The feeding of the printed dipole antenna is mainly performed by feeding a coplanar strip (CPS) together with the dipole on one side of the dielectric substrate, or by placing the dipoles and the strips on both sides of the dielectric substrate. Mainly used. However, the bandwidth of the printed dipole antenna is generally 15 to 20%, and there is a problem that the bandwidth is very narrow to provide various mobile communication and wireless communication services.

As a conventional technique for increasing the bandwidth of a printed dipole antenna for solving the above problems, [Paper 1: MC Bailey, "Broad-Band Half-Wave Dipole", IEEE Transactions on Antennas and Propagation , AP-32 , No. 4, pp. 410-412, Apr. 1984.], [Paper 2: E. Levine, S. Shtrikman, and D. Treves, "Double-sided printed arrays with large bandwidth," IEE Proc. Pt. H , Vol. 135, No. 1, pp. 54-59, Feb. 1988.] and [Paper 3: Jeong Il Kim, Byung Moo Lee, Young Joong Yoon, "Wideband Printed Dipole Antenna for Multiple Wireless Services," RAWCON (Radio and Wireless Conference) 2001 , Vol. 1, pp. 153-156, Aug. 2001, respectively.

Here, the characteristics of the printed dipole antennas presented in each paper are as follows.

[Paper 1] modified the shape of the dipole arm into a triangular shape such as a bowtie antenna in order to increase the bandwidth of the printed dipole, and the arm of one arm was the other arm. It has a slightly shorter structure. However, the printed dipole antenna according to [Paper 1] also has a problem of obtaining a bandwidth of only 37%.

The printed dipole antenna presented in [Paper 2] includes a spacer between the grounding conductor plate and the radiating plate, and twin-lines connected to the dipole for feeding the dipole are connected to both sides of the substrate. It has a structure located at. However, the printed dipole antenna presented in [Paper 2] also has a limit of about 25% of its bandwidth.

In addition, [Paper 3] proposes a broadband design guide to obtain the maximum bandwidth, has a reflector on the back of the radiating element to form a unidirectional radiation pattern, and the dipole directly from the 50Ω coaxial line. A structure for feeding power to each arm is formed. According to [Paper 3], when VSWR ≤ 2, a broadband dipole antenna having a bandwidth of 82% can be designed, but since the coaxial line, which is an unbalanced line, is directly connected to the dipole, surface current flows to the outer conductor of the coaxial line. There is a serious problem that the current forms an additional resonance with the influence of the reflecting plate and forms unnecessary radiation, thereby degrading the characteristics of the antenna.

The present invention has been proposed to solve all the problems of the prior art as described above, by providing a broadband design guide of the dipole antenna, to provide a wideband printed dipole antenna for transmitting and receiving electromagnetic signals over a wide band The purpose is.

In addition, the present invention combines a balun for feeding a dipole antenna according to the broadband design guidelines, thereby enabling the transmission and reception of electromagnetic signals over a wide band, and a wideband printed dipole to achieve a unidirectional radiation pattern and high antenna gain. The purpose is to provide an antenna.

1 is a perspective view of a first embodiment of a broadband printed dipole antenna according to the present invention;

2 is a graph illustrating an exemplary return loss of the antenna of FIG. 1;

3A is a perspective view of a second embodiment of a broadband printed dipole antenna according to the present invention;

FIG. 3b is a plan view of the FIG.

FIG. 3C is a side view of FIG. 3A;

4 is a structural diagram of a lambda / 4 coaxial line balun applied to the present invention,

5A is an embodiment diagram showing an E-plane radiation pattern of the antenna of FIG.

5B is an embodiment diagram illustrating an H plane radiation pattern of the antenna of FIG. 3;

FIG. 6 is an exemplary graph illustrating boresight directional antenna gain of the antenna of FIG.

7A is a plan view of a third embodiment of a broadband printed dipole antenna according to the present invention;

FIG. 7B is a side view of FIG. 7A;

FIG. 7C is a perspective view of FIG. 7A;

8A is a plan view of a fourth embodiment of a broadband printed dipole antenna according to the present invention;

8B is a side view of FIG. 8A,

8C is a front view of FIG. 8A,

8D is a perspective view of FIG. 8A,

9 is an exemplary graph illustrating return loss of a wideband printed dipole antenna according to various embodiments of the present disclosure.

* Explanation of symbols for the main parts of the drawings

100: printed dipole 110: dielectric substrate

120: power supply means 310: reflector

320, 330: λ / 4 coaxial line balun 710, 720: CPS balun

810, 820, 830: tapered balun

In order to achieve the above object, the present invention provides a broadband printed dipole antenna positioned on an upper surface of a dielectric substrate and having a power supply means for transmitting and receiving an electromagnetic signal over a wide band, the width (W) and the length of the printed dipole. (L) ratio (W / L) is substantially greater than or equal to 0.9, and has any one of ratios less than or equal to 1.1, characterized in that the spacing (G) between the printable dipole is substantially 0.1L do.

In addition, the present invention provides a wideband printed dipole antenna for transmitting and receiving electromagnetic signals over a wideband and for unidirectional radiation patterns and high antenna gain, comprising: a printed dipole disposed on one surface of a dielectric substrate; Reflecting means disposed on a rear surface of the printed dipole and connected to ground to form a unidirectional radiation pattern; And a balloon disposed vertically between the printed dipole and the radiating means, for supplying a balanced current to the printed dipole.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a structural diagram of a first embodiment of a broadband printed dipole antenna according to the present invention.

As shown in the figure, in the broadband printed dipole antenna of the present invention, a rectangular printed dipole 100 is formed on the dielectric substrate 110 by photo etching, and the arm of the printed dipole 100 is formed. The feed 120 is made in the center between the arms.

In general, a method of increasing the thickness of the dipole may be used to increase the bandwidth of a cylindrical dipole, in which case the weight and cost of the antenna are increased. As an alternative, a light and inexpensive printed dipole can be considered, but similar to the cylindrical dipole, a method of increasing the width of the printed dipole can be considered to obtain broadband characteristics.

However, the continuous increase in the width does not increase the bandwidth continuously, so that the ratio of the width (W) and length (L) of the arm of the printed dipole 100 to obtain the maximum bandwidth in a good matching state is obtained. The distance G between the arms of the printable dipole 100 should be determined.

In the present invention, the value of W / L is 0.9 to 1.1, that is, approximately 1 is given, and G is approximately 0.1L. In this case, the operating frequency band may be determined by the following equation.

In this case, λ _o is the wavelength of the center frequency of the band for forming the bandwidth.

If the ratio of the width and the length (W / L) of each arm of the dipole is different, that is, for example, W / L = 0.8, the matching degree is lowered but a wider bandwidth can be obtained. (Reflection loss criterion is lowered from 15dB to 10dB with wider bandwidth), which follows the gain-bandwidth theorem of Pano. However, it can be said that the design criterion proposed by the present invention is suitable for designing a broadband antenna according to the degree of matching that determines the bandwidth which is being enhanced.

2 is a graph illustrating an example of return loss of the antenna of FIG. 1.

As shown in the figure, the broadband printed dipole antenna of the present invention has a bandwidth of 70% and 52% based on VSWR ≤ 2 and VSWR ≤ 1.5, respectively, when W / L = 1, and W / L = 0.8, the bandwidths of 80% and 27%, respectively, based on VSWR 2 and VSWR 1.5.

3A is a structural diagram of a second embodiment of a broadband printed dipole antenna according to the present invention.

As shown in the figure, the broadband printed dipole antenna of the present invention includes a reflecting plate 310 and λ / 4 (λ is a wavelength in free space) coaxial line baluns 320 and 330.

The reflective plate 310 made of a metal connected to the ground is positioned on the rear surface of the printed dipole 100 according to the design described with reference to FIG. 1, and between the printed dipole 100 and the reflective plate 310. The [lambda] / 4 coaxial line balun (340, 350) is located for feeding a balanced current. In this case, since the printed dipole 100 is positioned in the direction of the reflecting plate 310, the printed dipole 100 is positioned on the bottom surface of the dielectric substrate 110.

3B is a plan view of FIG. 3A, and FIG. 3C is a side view of FIG. 3A.

As shown in the figure, the λ / 4 coaxial line baluns 320 and 330 of the broadband printed dipole antenna of the present invention may use the λ / 4 coaxial cable 320 and a metal rod 330 of such thickness. The outer conductor and the metal rod 330 of the coaxial line 320 are connected to each arm of the printable dipole 100 one by one, and are simultaneously connected to the reflector plate 310.

The inner core 340 of the coaxial line 320 passes through the dielectric substrate 110 and is connected to the metal rod 330 again. This is the same as the operating principle of the general 1: 1 λ / 4 coaxial line balun shown in FIG.

Hereinafter, the operation principle of the λ / 4 coaxial line balun applied to the present invention will be described with reference to FIG. 4.

4 is a structural diagram of a λ / 4 coaxial line balun applied to the present invention.

As shown in the figure, an additional [lambda] / 4 length metal rod 430 connected to the dipole arm 410 (A) is connected to the outer conductor of the coaxial line 420 (B), so that the input impedance of the dipole Shut off the leakage current to the outer conductor of the coaxial line without affecting it.

If this type of balun is not combined and power is supplied by only one coaxial line, leakage current flows to the outer conductor of the coaxial line, resulting in distortion of the radiation pattern. Also, depending on the length between the dipole and the reflector, the resonance phenomenon at a specific resonance frequency Will appear.

3C, the distance d between the printed dipole 100 and the reflector 310 simultaneously affects the bandwidth and the radiation pattern. As the distance d increases, the bandwidth increases. However, since the distance d should be lambda / 4 to cause constructive interference in the boresight direction to maximize the antenna gain, the distance d should be selected in consideration of the frequency band to be used.

In particular, in the case of an antenna having a very wide bandwidth as in the present invention, at an frequency within the bandwidth, it may have both electrical lengths of λ / 4 and λ / 2 with respect to the same physical length d. In this case, FIGS. As in the 3.5 GHz (λ / 2) radiation pattern of FIG. 5B, nulls are generated in the boresight direction.

In addition, as shown in FIG. 6, the antenna gain in the boresight direction may be minimized at a frequency at which the distance d becomes λ / 2 due to null of the radiation pattern.

5A is an exemplary diagram illustrating an E-plane radiation pattern of the antenna of FIG. 3.

As shown in the figure, the E-plane radiation pattern of the broadband printed dipole antenna of the present invention forms an electrical length of λ / 4 at 1.75 GHz with respect to the physical length d to form a boresight direction. Although constructive interference is caused at 3.5 GHz, an electrical length of λ / 2 is formed to cause destructive interference in the boresight direction to form a null.

This is always the case with very wide bandwidth antennas with reflectors, as in the case of a cavity-backed spiral antenna, a radio absorber can be placed between the radiating element and the reflector to solve this problem. In this case, however, the antenna gain is reduced.

FIG. 5B is an embodiment diagram illustrating an H plane radiation pattern of the antenna of FIG. 3.

As shown in the figure, the H plane radiation pattern of the broadband printed dipole antenna of the present invention, the same phenomenon occurs as the E plane radiation pattern shown in FIG. 5A.

FIG. 6 is an exemplary graph illustrating the boresight directional antenna gain of the antenna of FIG. 3.

As shown in the figure, the bore sight directional antenna gain of the wideband printed dipole antenna of the present invention has a unidirectional radiation pattern, so that the gain is increased by about twice as much as without the reflector.

However, it can be seen that the change in the antenna gain in the boresight direction is caused by the change in the electrical length of the physical length d according to the frequency change.

7A is a plan view of a third embodiment of a broadband printed dipole antenna according to the present invention, FIG. 7B is a side view of FIG. 7A, and FIG. 7C is a perspective view of FIG. 7A.

As shown in the figure, the broadband printed dipole antenna of the present invention includes a reflector plate 310 and CPS baluns 710 and 720.

The reflective plate 310 made of a metal connected to the ground is positioned on the rear surface of the printed dipole 100 according to the design described with reference to FIG. 1, and between the printed dipole 100 and the reflective plate 310. There is a CPS feed line 720 for feeding a balanced current.

In this case, the printed dipole 100 is located on the top surface of the dielectric substrate 110 to be separated from the CPS baluns 710 and 720, and the printed dipole 100 and the CPS feed line 720 are separated from each other. A metal pin 730 for connecting passes through the dielectric substrate 110.

In addition, one side of the CPS feed line 720 is connected to the reflective plate 310, the other side is to be separated by drilling a hole (C) in the metal plate.

The CPS baluns 710 and 720 are composed of the CPS feed line 720 formed by photo etching on the dielectric plate 710 as shown in FIG. 7C, which is characterized by a balanced line.

The distance d between the dielectric substrate 110 and the reflecting plate 310 is selected to be the same as in the second embodiment of FIG. 3 and exhibits similar operating principles and performances.

8A is a plan view of a fourth embodiment of a broadband printed dipole antenna according to the present invention, FIG. 8B is a side view of FIG. 8A, FIG. 8C is a front view of FIG. 8A, and FIG. 8D is a perspective view of FIG. 8A.

As shown in the figure, the broadband printed dipole antenna of the present invention includes a reflector plate 310 and tapered baluns 810, 820, and 830.

A reflecting plate 310 made of a metal connected to the ground is positioned on the rear surface of the printed dipole 100 according to the design described with reference to FIG. 1, and is equilibrated between the printed dipole 100 and the reflecting plate 310. Tapered baluns 810, 820, 830 for feeding current are located.

In this case, the printed dipole 100 is positioned on the bottom surface of the dielectric substrate 110 to be directly connected to the tapered baluns 810, 820, and 830. In addition, the tapered strip line 830 serving as the ground of the tapered baluns 810, 820, and 830 is connected to the reflecting plate 310, and the straight strip line 820 drills a hole D in the metal plate. To be separated.

As shown in FIG. 8D, the tapered baluns 810, 820, and 830 include the straight strip line 820 and the tapered strip line 830 formed by photo etching on both sides of the dielectric plate 810. The parallel strip portion (balanced line) from the microstrip line portion (unbalanced line) (the two width portions of the two lines disposed on the reflector plate 310 side) and the parallel line portion (side of the printed dipole 100 side) The width of the two lines is the same part) and is configured to change while showing broadband characteristics.

The distance d between the dielectric substrate 110 and the reflecting plate 310 is selected to be the same as in the second embodiment of FIG. 3 and exhibits similar operating principles and performances.

9 is a graph illustrating an example of return loss of a broadband printed dipole antenna according to various embodiments of the present disclosure.

As shown in the figure, the antennas including the λ / 4 coaxial line balun, the CPS balun, and the tapered balun of the present invention have a bandwidth of 93%, 80%, and 73% based on VSWR ≤ 2, respectively.

In the present invention as described above, a dipole radiating element having a design value having a broadband characteristic is formed on one surface of a dielectric substrate by a photo etching technique, and the balun is dipole so that a balanced current can be fed in the center between the dipole arms. By placing the reflector in a vertical position between the reflector and the reflector at an appropriate distance behind the dipole, a radiation pattern in a single direction can be formed and the antenna gain can be increased.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the technical field of the present invention without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The present invention as described above provides a much wider bandwidth than microstrip antennas with similar advantages, by incorporating a balun into a printed dipole antenna, less surface wave excitation, and unnecessary from feeder lines. There is an effect that can reduce spurious radiation.

In addition, in the hardware design of the printed dipole antenna, the present invention has a light weight, a simple manufacturing process, and an inexpensive manufacturing cost.

In addition, the present invention has the effect that can be used in a system to provide a number of wireless services with one antenna.

Claims (19)

In the broadband printed dipole antenna which is provided on the upper surface of the dielectric substrate and provided with a power supply means for transmitting and receiving the electromagnetic signal over a wide band, The ratio (W / L) of the width (W) and length (L) of each arm of the printable dipole has a ratio of substantially greater than or equal to 0.9 and less than or equal to 1.1, wherein the printable dipole arm And the spacing G between them is substantially 0.1L. The method of claim 1, The broadband printed dipole antenna is a broadband printed dipole antenna, characterized in that the operating frequency band is determined by the following equation. (Where L is the length of the printable dipole arm, G is the distance between the printable dipole arms, and λ _o is the wavelength at the center frequency of the frequency band forming the bandwidth) A broadband printed dipole antenna for transmitting and receiving electromagnetic signals over a wide band and for unidirectional radiation patterns and high antenna gain, A printed dipole disposed on one surface of the dielectric substrate; Reflecting means disposed at a predetermined distance from the dielectric substrate and connected to ground to form a radiation pattern in a single direction; And A balun disposed between the printable dipole and the reflecting means, for feeding a balanced current to the printable dipole Broadband printed dipole antenna comprising a. The method of claim 3, wherein Disposed to occupy the space between the dielectric substrate and the reflecting means, and further eliminating nulls of the radiation pattern occurring in the bore site direction as the frequency increases, and further adding a radio wave absorber to prevent the antenna gain from decreasing. Broadband printed dipole antenna comprising. The method of claim 3, wherein The printable dipole is, A wideband printed dipole antenna, characterized in that the ratio (W / L) of the width (W) and length (L) of each arm is substantially greater than or equal to 0.9. The method of claim 3, wherein The printable dipole is, A wideband printed dipole antenna, characterized in that the spacing G between each arm is substantially 0.1 times (0.1L) the length of each arm. The method of claim 3, wherein The broadband printed dipole antenna is a broadband printed dipole antenna, characterized in that the operating frequency band is determined by the following equation. (Where L is the length of the printable dipole arm, G is the distance between the printable dipole arms, and λ _o is the wavelength at the center frequency of the frequency band forming the bandwidth) The method of claim 3, wherein The distance between the dielectric substrate and the reflecting means, and λ / 4 (λ is a wavelength in free space). The method of claim 3, wherein The balun, λ / 4 (λ is a wavelength in free space) A broadband printed dipole antenna, characterized in that it is a coaxial line balun. The method of claim 3 or 8, The printable dipole is, Broadband printed dipole antenna, characterized in that located on the bottom surface of the dielectric substrate. The method of claim 9, The λ / 4 coaxial line balun is A λ / 4 length coaxial line having an inner core, arranged to connect any one of the arms of the printed dipole and the reflecting means, and to supply a balanced current to the printed dipole; And A metal rod arranged to connect the other one of the arms of the printed dipole and the reflecting means, and to block leakage current flowing to an outer conductor of the coaxial line. Broadband printed dipole antenna comprising a. The method of claim 11, The inner core of the coaxial track is And a broadband printed dipole antenna disposed through the dielectric substrate and connected to the metal rod. The method of claim 3, wherein The balun, Wideband printed dipole antenna, characterized in that it is a coplanar strip (CPS) balun. The method according to claim 3 or 13, The printable dipole is, Broadband printed dipole antenna, characterized in that located on the upper surface of the dielectric substrate. The method of claim 12, The CPS balun, A metal pin for feeding the printed dipole; And a CPS feed line formed on one surface of the dielectric plate by photo etching, wherein a portion of the reflecting means contacting the feed line of any one of the CPS feed lines is removed. The method of claim 15, The metal pin, And a printed circuit board configured to connect the printed dipole and the CPS feed line. The method of claim 3, wherein The balun, A broadband printed dipole antenna, characterized in that it is a tapered balun. The method according to claim 3 or 17, The printable dipole is, Broadband printed dipole antenna, characterized in that located on the bottom surface of the dielectric substrate. The method of claim 17, The tapered balun, A strip line line formed by photo etching on one surface of the dielectric plate and a taper strip line formed by photo etching on the other surface of the dielectric plate, wherein portions of the reflecting means in contact with the straight strip line are removed and formed. Broadband printed dipole antenna.