KR101345764B1 - Quasi yagi antenna - Google Patents

Abstract

The present invention relates to a quasi-yagi antenna. The provided quasi-yagi antenna includes: a feeding unit; a dipole inductor which is fed by the feeding unit and radiates radio waves; and a director which is placed at a distance from the dipole inductor and directs the radiation direction of the radio waves to a certain direction. The director includes a pair of split ring resonators which radiate the radio waves in a multi frequency band.

Description

Quasi Yagi antenna {QUASI YAGI ANTENNA}

The present invention relates to a quasi Yagi antenna.

With the recent rapid development of wireless communication technology, antennas having various structures have been proposed as part of improving the transmission efficiency of radio waves. Among these antennas, a quasi yagi antenna has a structure in which a waveguide (director) is arranged in front of a driver and a reflector (reflector) is arranged in a rear side of the antenna. On the other hand, due to the explosive increase in data communication demand, for example, through a multi-band, such as the Wireless Local Area Network (WLAN) band of 5GHz frequency, or the WiMAX (Widemax) band of 3GHz frequency, etc. There is a need for an antenna that implements transmission characteristics. However, the existing quasi-cause antenna can support only data transmission through a single band. If a quasi-cause antenna is used to transmit radio waves through a low frequency band, the length of the inductor and the waveguide must be increased, resulting in an increase in the size of the antenna.

An object of the present invention is to provide a quasi-cause antenna capable of directing radio waves in a predetermined direction and capable of emitting radio waves through multiple frequency bands.

Another object of the present invention is to provide a quasi-cause antenna having miniaturization and at the same time having directivity and multi-band transmission characteristics.

The problems to be solved by the present invention are not limited to the above-mentioned problems. Other technical subjects not mentioned may be clearly understood by those skilled in the art from the following description.

Quasi-cause antenna according to an aspect of the present invention the power supply; A dipole induction unit that is fed by the feeding unit and radiates radio waves; And a waveguide formed at a position spaced apart from the dipole inductor to direct the radiation direction of the radio wave in a predetermined direction, wherein the waveguide includes a pair of split ring resonators for radiating the radio wave through multiple frequency bands. do.

According to an aspect of the present invention, the pair of split ring resonators are formed to be symmetrical with respect to the point of contact of the dipole inductor, and each of the pair of split ring resonators has a quasi-giving ring-shaped ring shape. An antenna may be provided.

According to an aspect of the present invention, the pair of gaps formed in the pair of split ring resonators are quasi-causal formed to face in opposite directions on the opposite surface of the pair of split ring resonators. An antenna may be provided.

According to an aspect of the present invention, the waveguide further includes an inner split ring resonator formed inside each of the pair of split ring resonators, wherein the inner split ring resonator is formed in a ring shape with a gap, and the inner split The gap of the ring resonator may be provided with a quasi-cause antenna formed on the surface of the internal split ring resonator opposite to the surface on which the gap of the split ring resonator is formed.

According to an aspect of the present invention, the gap of each of the pair of split ring resonators, the quasi-cause antenna is formed to extend from both ends of the gap toward the inside of each of the pair of split ring resonators Can be provided.

According to an aspect of the present invention, each of the pair of split ring resonators may be provided with a quasi-cause antenna formed of a circular or rectangular ring shape.

According to an aspect of the invention, the power supply unit, a microstrip feed surface for receiving power; A coplanar stripline for feeding said dipole inductor; And a balun that connects the microstrip feed surface to the coplanar strip line.

According to an aspect of the invention, the feeder, the dipole inductor and the waveguide is further formed on the top surface of the dielectric substrate, the lower surface of the dielectric substrate performs a reflector function of the quasi-cause antenna A quasi-cause antenna may be provided in which a ground plane is formed.

According to an aspect of the invention, the dipole inductor is formed with a length corresponding to the inverse of the first frequency in the multi-frequency band, each of the pair of split ring resonators are smaller than the first frequency in the multi-frequency band A quasi-cause antenna formed to a length corresponding to the inverse of the second frequency may be provided.

According to an embodiment of the present invention, it is possible to provide a quasi-cause antenna capable of directing radio waves in a predetermined direction and emitting radio waves through multiple frequency bands.

In addition, according to the embodiment of the present invention, it is possible to provide a quasi-cause antenna having a miniaturization characteristic with directivity and multi-band characteristics.

1 is a plan view of a quasi-cause antenna according to an embodiment of the present invention.
2 is a plan view (a) and a rear view (b) of a quasi-cause antenna according to an embodiment of the present invention.
3 is a graph showing the return loss for each frequency of the quasi-cause antenna according to an embodiment of the present invention.
4 is a graph showing the radiation pattern of the conventional antenna and the radiation pattern of the quasi-cause antenna according to an embodiment of the present invention.
FIG. 5 is a graph illustrating frequency-specific return loss with respect to the width of various split ring resonators of a quasi-cause antenna according to an exemplary embodiment of the present invention.
6 is a plan view of a quasi-cause antenna according to another embodiment of the present invention.
7 is a plan view of a quasi-cause antenna according to another embodiment of the present invention.
8 is a plan view of a quasi-cause antenna according to another embodiment of the present invention.
9 is a graph illustrating return loss for each frequency of a quasi-cause antenna according to various embodiments of the present disclosure.

Other advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Unless defined otherwise, all terms (including technical or scientific terms) used herein have the same meaning as commonly accepted by the generic art in the prior art to which this invention belongs. Terms defined by generic dictionaries may be interpreted to have the same meaning as in the related art and / or in the text of this application, and may be conceptualized or overly formalized, even if not expressly defined herein I will not. The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, various uses of " comprises " and / or the verb do not exclude the presence or addition of one or more other elements, acts, and / or elements other than the mentioned elements, operations, and / or elements.

A quasi-Yagi antenna according to an embodiment of the present invention implements a waveguide using a split ring resonator (SRR) to direct a radio wave in a predetermined direction, Radio waves can be radiated through multiple frequency bands. In addition, the quasi-cause antenna according to an embodiment of the present invention can transmit and receive a low frequency band by using a small split ring resonator, and thus may have a miniaturized size.

1 is a plan view of a quasi-cause antenna according to an embodiment of the present invention. 2 is a plan view (a) and a rear view (b) of a quasi-cause antenna according to an embodiment of the present invention. 1 and 2, the quasi-cause antenna 100 according to an embodiment of the present invention is implemented as a single planar quasi-Yagi antenna, and includes a dielectric substrate 110 and a feeder ( 120, dipole inductor 130, waveguide 140, and ground plane 150.

The dielectric substrate 110 may be implemented as a single dielectric having a metal surface on its top and bottom surfaces. A feeder 120, a dipole inductor 130, and a waveguide 140 may be formed on the top surface 111 of the dielectric substrate 110. The feeder 120 may feed the dipole inductor 130. In one embodiment, the feeder 120 may include a microstrip feed surface 121, a balloon 122, and a coplanar stripline 123. The microstrip feed surface 121 may receive power. The balloon 122 may connect the microstrip feed surface 121 to the coplanar stripline 122. In one embodiment, the BALUN (BALance to UNbalance transformer) 122 is a matching transformer, the parallel two-wire line of the coplanar stripline 122 and the unbalance of the microstrip feed plane 121. The line can be connected. The coplanar stripline 123 may feed the dipole inductor 130.

The dipole inductor 130 may be fed by the feeder 120 to radiate radio waves. The dipole inductor 130 may radiate radio waves using two dipole elements provided in a symmetrical form. The waveguide 140 may be formed at a position spaced apart from the dipole inductor 130 to direct the radiation direction of the radio wave in a predetermined direction. An orbit point 131 may be formed at the central portion of the dipole inductor 130. The ground plane 150 may function as a reflector of the quasi-cause antenna 100. The ground plane 150 may be formed on the bottom surface 112 of the dielectric substrate 110.

In one embodiment, the waveguide 140 may be implemented with a pair of Sprit Ring Resonators (SRRs) 141 and 142 to radiate radio waves through multiple frequency bands. The pair of split ring resonators 141 and 142 may be formed in a symmetrical form with respect to the point of contact 131 of the dipole inductor 130. Each of the pair of split ring resonators 141 and 142 may be formed in the shape of a metal ring having gaps 1412 and 1422 formed therein. Although the split ring resonators 141 and 142 are shown to have a rectangular ring shape in the embodiment of FIG. 1, the split ring resonators 141 and 142 may be deformed into a circular ring or the like.

The gap 1412 of the first split ring resonator 141 may be formed on a surface 1411 of the first split ring resonator 141 opposite to a surface facing the second split ring resonator 142. The gap 1422 of the second split ring resonator 142 may be formed on a surface 1421 of the second split ring resonator 142 opposite to a surface facing the first split ring resonator 141. That is, the pair of gaps 1412 and 1422 of the pair of split ring resonators 141 and 142 may be formed to face in opposite directions. As such, since the gaps 1412 and 1422 of the split ring resonators 141 and 142 are separated from each other in opposite directions while facing the outside of the antenna, the gaps 1412 and 1422 have an effect of operating as an electric dipole while minimizing a coupling effect between the gaps.

The split ring resonators 141 and 142 operate by a time varying magnetic field applied in the vertical direction thereof, and operate as LC resonators which are electrically small and have high Q values. Accordingly, the quasi-cause antenna 100 according to the embodiment of the present invention may implement dual band transmission characteristics by two frequency operation modes of the split ring resonators 141 and 142, and maintain the inherent directivity characteristic of the quasi-cause antenna. Can be.

Physical parameters of the quasi-cause antenna 100 according to an embodiment of the present invention may be designed in consideration of the transmission frequency band. In one embodiment, the physical parameters of the quasi-cause antenna 100 may be optimized by Ansoft's High Frequency Structure Simulator (HFSS). For example, referring to FIG. 2, the following values may be selected for the design of the quasi-cause antenna 100 having dual band characteristics of the 3 GHz band and the 5 GHz band.

Thickness of dielectric substrate 110 = 0.812 mm, dielectric constant of dielectric substrate 110 = 3.55, L1 = 9.1 mm, L2 = 15.7 mm, L3 = 4.9 mm, L4 = 3.1 mm, L5 = 4 mm, L6 = 11.4 mm, L7 = 25.75 mm, L8 = 9.5 mm, L9 = 28.5 mm, W1 = 1.85 mm, W2 = 3.6 mm, W3 = 0.9 mm, W4 = 1.2 mm, d1 = 1.25 mm, d2 = 8 mm, g1 = 0.75 mm, and g2 = 0.7 mm

The length of the dipole inductor 130 is designed to have a half wavelength length (λ / 2, λ is the wavelength of the radio wave). The balloon 122 may be implemented by impedance matched T junction and a delay of a microstrip line of half wavelength length ( L ₃ -L ₂ = λ / 4) at a design frequency (first frequency). . The quasi-gigi antenna 100 designed as described above was fabricated and its characteristics are measured and shown in FIGS. 3 and 4.

3 is a graph illustrating return loss for each frequency of a quasi-cause antenna according to an exemplary embodiment of the present invention. In FIG. 3, a graph with a dashed-dotted line shows the return loss by frequency of the conventional antenna, and a graph with the dotted line shows the return loss by frequency through the simulation of the quasi-cause antenna 100 according to the embodiment of the present invention, and a solid line The graph shows the return loss by frequency of the quasi-cause antenna 100 manufactured according to the embodiment of the present invention. As a conventional antenna, a quasi-gigi antenna having a waveguide made of a dipole element is used. Return loss was measured by Anritsu's network analyzer 38397C.

As shown in FIG. 3, it can be seen that the conventional antenna operates in a single band requiring a return loss of less than -10 (dB) in the 5 GHz band, that is, the frequency band of 5 to 5.57 GHz. In contrast, the quasi-cause antenna 100 according to the embodiment of the present invention has two operating modes operating in both the 3 GHz WiMAX band FB2 and the 5 GHz WLAN band FB1. That is, the quasi-cause antenna 100 according to the embodiment of the present invention has a dual band characteristic due to the split ring resonator mode and the parasitic mode.

The first mode is a parasitic mode generated in the WLAN 5 GHz band FB1, and the split ring resonators 141 and 142 may operate in a form similar to a typical waveguide as a parasitic element. The second mode is the split ring resonator mode in which the dipole inductor 130 of the antenna applies a time varying magnetic field in the vertical direction of the split ring resonators 141 and 142 so that the split ring resonators 141 and 142 operate as typical resonators in the WiMAX band FB2. to be. In particular, the quasi-gigi antenna 100 operating in the split ring resonator mode has a dipole inductor 130 having a half-wave length in the 5.2 GHz band, and thus operates at a resonance frequency of 3.45 GHz. By comparison, it can be miniaturized electrically.

4 is a graph showing the radiation pattern of the conventional antenna and the radiation pattern of the quasi-cause antenna according to an embodiment of the present invention. In Fig. 4, the graph with the dashed-dotted line shows the radiation pattern of the conventional antenna, and the graph with the dotted line shows the radiation pattern at 3.45 GHz frequency of the quasi-cause antenna according to the embodiment of the present invention, and the graph with the solid line is shown. The radiation pattern of the quasi-cause antenna according to the embodiment of the present invention at a frequency of 5.2 GHz.

The parasitic mode of 5.2 GHz frequency has a radiation pattern that is almost similar to a conventional quasi-cause antenna. In addition, even in the split ring resonator mode of the 3.45 GHz frequency, it has a pattern that maintains the intrinsic directivity of the quasi-cause antenna. The directivity of the radiation pattern at 3.45 GHz frequency of the quasi-cause antenna according to the embodiment of the present invention is 5.7 dBi (radiation efficiency 0.61), and the directivity of the radiation pattern at 5.2 GHz frequency is 6.3 dBi (radiation efficiency 0.84). In other words, the directivity in the two frequency bands does not show a big difference.

In the embodiment of the present invention, the split ring resonators 141 and 142 constituting the waveguide have an overall length of the ring to produce an inductance component, and the gaps 1412 and 1422 of the split ring resonators 141 and 142 produce a capacitance component. Then, the resonance frequency is generated as shown in Equation 1 below.

[Formula 1]

(f ₀ is the resonance frequency (Hz), L is the inductance (H) component of the split ring resonator, C is the capacitance (F) component of the split ring resonator)

5 is a graph showing the return loss for each frequency with respect to the size of the various split ring resonators of the quasi-cause antenna according to an embodiment of the present invention. In FIG. 5, the graph with a dashed-dotted line shows the reflection loss for each frequency when the widths of the split ring resonators 141 and 142 of the quasi-cause antenna 100 according to the embodiment of the present invention are 8.5 mm, and the graph with the solid line is shown in FIG. According to an embodiment of the present invention, when the widths of the split ring resonators 141 and 142 of the quasi-cause antenna 100 are 9.0 mm, the graph shows a return loss for each frequency, and the dotted line graph shows a width of the split ring resonators 141 and 9.5 as 9.5. In the case of mm, the return loss by frequency is shown.

Referring to FIG. 5, when the length L8 of one side of the split ring resonators 141 and 142 is changed, since the resonant frequencies of the split ring resonators 141 and 142 are shifted, the frequency band of the split ring resonator mode is changed. That is, as the length L8 of one side of the square split ring resonators 141 and 142 is increased from 8.5 mm to 9.0 mm and 9.5 mm, the frequency band of the split ring resonator mode is increased in the 3.7 GHz band (FB21). It can be seen that the 3.5 GHz band (FB22), 3.4 GHz band (FB23) in order to gradually move toward a lower frequency. This is because the inductance component increases as the size of the split ring resonators 141 and 142 increases, thereby lowering the resonance frequency. At this time, it can be seen that the 5.2 GHz frequency band FB1 in the parasitic mode can be maintained without significantly changing its characteristics despite the size change of the split ring resonator.

Basically, the 'resonator' and 'antenna' may have contradictory concepts in terms of 'non-radiation' and 'radiation', but the split ring resonator used as the waveguide 140 in the embodiment of the present invention ( 141 and 142 may have a relatively low Q value. Due to the low Q characteristic of the split ring resonator, the waveguide 140 of the resonator type having 'non-radiation' may be mounted on the antenna. According to the embodiment of the present invention, since the split ring resonators 141 and 142 operate as waveguides by an electrically miniaturized inductor in the split ring resonator mode, the antenna can be miniaturized. In this case, the characteristic and directivity pattern in the parasitic mode of the quasi-cause antenna 100 may be maintained as it is.

In one embodiment, the dipole inductor 130 may be formed to a length corresponding to the inverse of the first frequency (5.2 GHz of the FB1 band) of the multiple frequency band. In one embodiment, each of the pair of split ring resonators 141, 142 is a second frequency (3.4 GHz, 3.5 GHz, 3.7 GHz, etc. of the FB2 band) smaller than the first frequency of the multiple frequency bands, according to Equation 1 mentioned above. It may be formed in a length corresponding to the inverse of the). As such, by setting the physical parameters of the dipole inductor 130 and the split ring resonators 141 and 142 according to the frequency of the multi band, the quasi-cause antenna 100 having the multi-mode transmission characteristics can be designed.

6 is a plan view of a quasi-cause antenna according to another embodiment of the present invention. Of the components shown in the embodiment of FIG. 6, the same description as the embodiment of FIG. 1 will be omitted. Referring to FIG. 6, the split ring resonators 141 and 142 constituting the quasi-cause antenna 100 according to an exemplary embodiment of the present invention may be provided in a circular metal ring shape. In one embodiment, the diameters of the circular metal rings of the split ring resonators 141 and 142 and the sizes of the gaps 1412 and 1422 may be set to distances corresponding to the inverses of the low frequencies in the multiple frequency bands.

7 is a plan view of a quasi-cause antenna according to another embodiment of the present invention. Among the components shown in the embodiment of FIG. 7, duplicate descriptions of the same elements as those of the embodiment of FIG. 1 will be omitted. Referring to FIG. 7, the waveguide 140 constituting the quasi-cause antenna 100 according to an exemplary embodiment of the present invention may include internal split ring resonators 143 and 144 formed inside the pair of split ring resonators 141 and 142. It may further include. The internal split ring resonators 143 and 144 may have a ring shape in which a gap 1432 is formed. The internal split ring resonators 143 and 144 may have a shape corresponding to the split ring resonators 141 and 142. The surfaces 1431 of the internal split ring resonators 143 and 144, wherein the gaps 1432 and 1442 of the internal split ring resonators 143 and 144 are opposite to the surfaces 1411 and 1421 where the gaps 1412 and 1422 of the split ring resonators 141 and 142 are formed. 1441, it is possible to transmit and receive radio waves at a lower resonance frequency.

8 is a plan view of a quasi-cause antenna according to another embodiment of the present invention. Among the components shown in the embodiment of FIG. 8, the same description as the embodiment of FIG. 1 will be omitted. Referring to FIG. 8, gaps 1412 and 1422 of each of the pair of split ring resonators 141 and 142 extend from both ends of the gaps 1412 and 1422 to face the interior of each of the pair of split ring resonators 141 and 142. It can be formed in the form (1413,1414) (1423,1424). Accordingly, the capacitance components of the split ring resonators 141 and 142 may be increased, thereby enabling radio wave transmission and reception through a lower resonance frequency.

9 is a graph illustrating return loss for each frequency of a quasi-cause antenna according to various embodiments of the present disclosure. In FIG. 9, the graph shown by the solid line represents the reflection loss for each frequency of the quasi-cause antenna 100 according to the embodiment of FIG. 1, and the graph shown by the thin dotted line shows the quasi-cause antenna 100 according to the embodiment of FIG. 7. The graph shows the return loss by frequency and bold dotted line indicates the return loss by frequency of the quasi-cause antenna 100 according to the embodiment of FIG. 6, and the graph shown by the dashed-dotted line is shown in the embodiment of FIG. 8. The reflection loss for each frequency of the quasi-cause antenna 100 according to FIG. Referring to FIG. 9, the quasi-cause antenna 100 according to an exemplary embodiment of the present invention provides an effect of adding a dual band mode of the 2.7 to 3.5 GHz frequency band without significantly affecting the characteristics of the 5 GHz frequency band. Able to know. In addition, the quasi-cause antenna 100 according to the embodiment shown in FIG. 7 and the embodiment shown in FIG. 8 has an effect of shifting the resonant frequency to a lower frequency because it increases the inductance and capacitance. .

It is to be understood that the above-described embodiments are provided to facilitate understanding of the present invention, and do not limit the scope of the present invention, and it is to be understood that various modifications may be made within the scope of the present invention. Therefore, the technical protection scope of the present invention should be determined by the technical idea of the claims, and the technical protection scope of the present invention is not limited to the literary description of the claims, The invention of a category.

100: quasi-gigi antenna 110: dielectric substrate
120: feeder 121: microstrip feed surface
122: balloon 123: coplanar stripline
130: dipole inductor 131: feed point
140: waveguide 141, 142: split ring resonator
1412,1422: gap 143,144: internal split ring resonator
150: ground plane

Claims (9)

Feeding part;
A dipole induction unit that is fed by the feeding unit and radiates radio waves; And
It is formed at a position spaced apart from the dipole inductor, directing the radiation direction of the radio wave in a predetermined direction, and comprises a waveguide implemented by a pair of split ring resonators,
And the waveguide radiates the radio wave through multiple frequency bands. The method according to claim 1,
The pair of split ring resonators are formed to be symmetrical with respect to the point of revolution of the dipole inductor.
And a pair of split ring resonators each having a ring shape with a gap formed therein. The method of claim 2,
The pair of gaps formed in the pair of split ring resonators,
And a quasi-cause antenna formed on opposite surfaces of the pair of split ring resonators so as to face in opposite directions to each other. The method of claim 3,
The waveguide further includes an internal split ring resonator formed inside each of the pair of split ring resonators,
The internal split ring resonator is formed in a ring shape having a gap,
And the gap of the inner split ring resonator is formed on a surface of the inner split ring resonator opposite to a surface on which the gap of the split ring resonator is formed. The method of claim 2,
The gap of each of the pair of split ring resonators is
And a quasi-cause antenna extending from both ends of the gap toward the inside of each of the pair of split ring resonators. The method according to claim 1,
And each of the pair of split ring resonators has a circular or quadrangular ring shape. The method according to claim 1,
Wherein the power-
A microstrip feed surface for receiving power;
A coplanar stripline for feeding said dipole inductor; And
And a balun that connects the microstrip feed surface to the coplanar strip line. The method according to claim 1,
Further comprising a dielectric substrate,
The feeder, the dipole inductor and the waveguide are formed on an upper surface of the dielectric substrate,
And a ground plane formed on a lower surface of the dielectric substrate to perform a reflector function of the quasi-cause antenna. 9. The method according to any one of claims 1 to 8,
The dipole inductor is formed with a length corresponding to the inverse of the first frequency in the multiple frequency band,
Each of the pair of split ring resonators has a length corresponding to an inverse of a second frequency smaller than the first frequency in the multiple frequency band.

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