KR101671799B1 - Energy harvesting system using parasitic radiator - Google Patents

Abstract

The present invention relates to an energy collecting system, and more particularly, to an antenna for transmitting and receiving electromagnetic waves using a parasitic radiating element, which is capable of effectively collecting energy through a parasitic radiating element while suppressing deterioration of characteristics of the main radiating element Lt; / RTI >
The present invention relates to a main radiating element in which a radiation pattern is directional; A parasitic radiating element located behind the main radiating element and collecting energy radiated from the main radiating element; And a ground plane located below the main radiating element and the parasitic radiating element, wherein the parasitic radiating element is a loop radiating element having one rotation or a plurality of revolutions. .

Description

[0001] The present invention relates to an energy harvesting system using a parasitic radiator,

The present invention relates to an energy collecting system, and more particularly, to an antenna for transmitting and receiving electromagnetic waves using a parasitic radiating element, which is capable of effectively collecting energy through a parasitic radiating element while suppressing deterioration of the main radiating element. ≪ / RTI >

In recent years, problems such as depletion of fossil fuels and global warming have been continuously raised, and there is growing interest in so-called green technology for reducing excessive resource and energy consumption and improving efficiency.

As a part of this, a method of improving energy efficiency by receiving idle radio waves radiated in the air for wireless communication and broadcasting and collecting and utilizing energy therefrom has been attempted. For example, in Korean Patent Laid-Open Publication No. 10-2010-0118383 (published on Nov. 5, 2010), electromagnetic waves in the air are collected and converted into electrical energy in a power storage system of a building, And an electromagnetic energy harvesting apparatus using Rectenna arranged in a determined length.

However, as described above, when energy is collected by receiving idle radio waves radiated into the atmosphere, the amount of energy that can be obtained through the collection is very limited. This is because when the electromagnetic wave is radiated, the distance from the radiation antenna increases, and the power of the received signal is rapidly attenuated. It is reported that when energy is collected by collecting idle radio waves emitted in the air, electric power of about 1 mW or less can be obtained, and electric devices that can operate with this power are very limited The practicality is reduced.

Therefore, it is advantageous to receive the signal as close as possible to the radiating antenna in order to increase the energy yield from the electromagnetic wave. For example, there is a case where energy is collected close to a broadcasting antenna, a base station antenna for wireless communication, or a repeater antenna that emits electromagnetic waves with a large power. However, when another receiving antenna enters the near field of the radiating antenna for energy collection, the radiation characteristic of the antenna may be distorted, which may hinder the original function of the radiating antenna.

Accordingly, there is a demand for an energy collection system capable of efficiently collecting energy by receiving an electromagnetic wave signal without distorting the characteristics of the electromagnetic radiation antenna, but a proper solution has not yet been proposed.

It is an object of the present invention to provide an energy collecting system having a structure capable of efficiently collecting energy by being disposed close to an electromagnetic wave emitting antenna without distorting the characteristics of the electromagnetic wave radiating antenna The purpose is to provide.

According to an aspect of the present invention, there is provided an energy collection system including a main radiating element having a directional radiation pattern; A parasitic radiating element located behind the main radiating element and collecting a part of energy radiated from the main radiating element; And a ground plane positioned below the main radiating element and the parasitic radiating element, wherein the parasitic radiating element is a loop radiating element having one rotation or a plurality of revolutions.

Here, the main radiating element may be one of a monopole radiating element, a dipole radiating element, and a printed dipole radiating element.

In addition, the parasitic radiating element may have a rotation number determined in consideration of an operating frequency band and a radiation gain characteristic.

In addition, the number of rotations of the parasitic radiating element may include a predetermined operating frequency band, and may have a rotational speed capable of maximizing the radiation gain of the parasitic radiating element.

The height of the parasitic radiating element from the ground plane is set to a height at which the parasitic radiating element can collect the most energy from the main radiating element and a height at which the radiation characteristic change of the main radiating element can be minimized Lt; / RTI >

The parasitic radiating element may have a length of a wavelength of an operating frequency or a circumferential length of an odd multiple thereof.

The parasitic radiating element includes a loop radiating element pattern formed on one or more layers of an upper layer, a lower layer, and an inner layer of a printed circuit board, and a slit formed in the center of the loop of the loop radiating element. A feeding line to the main radiating element can be wired through the main radiating element.

Further, the main radiating element may be a printed dipole radiating element.

According to another aspect of the present invention, there is provided an energy collection system comprising: a predetermined electromagnetic wave generating source; And a parasitic radiating element disposed in proximity to the electromagnetic wave generating source, wherein the parasitic radiating element may have one rotation or a plurality of rotation numbers.

Here, the electromagnetic wave generating source includes a ground plane, and the parasitic radiating element is disposed at a predetermined distance from the ground plane, wherein a distance from the ground plane of the parasitic radiating element is a distance The largest amount of energy can be collected from the source of electromagnetic waves.

In addition, the number of rotations of the parasitic radiating element may include a predetermined operating frequency band, and may have a rotational speed capable of maximizing the radiation gain of the parasitic radiating element.

According to the present invention, a loop radiating element is disposed behind the main radiating element, and the structure such as the number of revolutions and the height is optimally used as a parasitic radiating element, so that the radiation characteristic of the main radiating element is not distorted, And an energy collection system capable of efficiently collecting energy.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a configuration diagram of an energy collecting system using a parasitic radiating element according to an embodiment of the present invention.
Fig. 2 is an explanatory view for explaining radiation characteristics of a loop radiating element. Fig.
FIG. 3 is a characteristic change simulation graph of the energy collection system when the height of the parasitic radiating element according to the embodiment of the present invention is changed.
4 is a photograph of an energy collection system using a parasitic element according to an embodiment of the present invention.
5 is a graph of reflection coefficient measurement in a main radiating element and a parasitic radiating element according to an embodiment of the present invention.
FIG. 6 is a graph of emission and coupling characteristics of an energy collecting system using a parasitic radiating element according to an embodiment of the present invention.
7 is an EIRP measurement environment setting diagram of an energy collection system using a parasitic radiating element according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments will be described in detail below with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components are not limited by the terms, and the terms are used only for the purpose of distinguishing one component from another Is used.

According to the present invention, when energy is collected by receiving idle radio waves radiated into the atmosphere according to the related art, the amount of energy that can be obtained through the collection of energy is very limited. To improve the energy, When a signal is received as close as possible to the antenna for transmitting the signal, the radiation characteristic of the antenna may be distorted by entering another reception antenna into the near field of the antenna, By optimally arranging the structure such as the number of revolutions and height of the loop radiating element so as to minimize the influence to the radiating element, it is possible to efficiently receive the electromagnetic wave signal by receiving the electromagnetic wave signal without distorting the radiation characteristic of the main radiating element Energy collection system.

Hereinafter, exemplary embodiments of an energy collection system using a parasitic element according to the present invention will be described in detail with reference to the accompanying drawings.

1 shows a structure of an energy collection system 100 using a parasitic radiating element according to the present invention. 1, the energy collecting system 100 using the parasitic radiating element according to the present invention includes a main radiating element 110 having a directional radiation pattern, a rear radiating element 110 positioned behind the main radiating element 110, A parasitic radiating element 120 for collecting a part of the energy radiated from the main radiating element 110 and a ground plane 130 positioned below the main radiating element 110 and the parasitic radiating element 120, At this time, the parasitic radiating element 120 uses a loop radiating element having one rotation or a plurality of revolutions.

1 (a), an energy collection system 100 using a parasitic element according to the present invention may include two radiating elements, that is, a main radiating element 110 and a parasitic radiating element 120 . The main radiating element 110 may be used for transmitting and receiving signals in a typical wireless communication system, for example, in the case of a radiating element of an antenna at a base station or a repeater. The parasitic radiating element 120 receives the electromagnetic waves radiated from the main radiating element 110 and collects energy while minimizing the influence on the main radiation characteristics of the main radiating element 110, thereby collecting signals outside the beam width. Therefore, the main radiating element 110 exhibits only a slight characteristic change, and the original characteristics can be maintained.

In the energy collecting system 100 using the parasitic radiating element according to the present invention, various kinds of radiating elements can be used. Here, a printed dipole radiating element is used as an embodiment of the present invention. Printed dipole (radiated) is widely used in wireless communication base station antennas because it has broadband and high gain characteristics and simple manufacturing process. Therefore, it is advantageous to implement energy collection system using it. have. In addition to the above-mentioned printed dipole radiation element, monopole radiation element and dipole radiation element having similar characteristics can be easily applied to the present invention, so that a wider application is possible Do.

In addition, a loop radiating element is used as the parasitic radiating element 120 as one embodiment of the present invention. The loop radiating element may have various shapes other than a circle, for example, rectangular, triangular, or other polygonal shapes. In particular, the resonant loop radiating element has a circumferential length close to the wavelength of the operating frequency (or an odd multiple thereof). The intensity of the induced voltage when a magnetic field is applied to the loop radiating element can be expressed by the following equation.

[Equation 1]

Where N is the number of revolutions of the loop radiating element, A is the area of the loop radiating element [m ² ], f is the operating frequency [GHz], B is the induction voltage The root mean square (RMS) value of the magnetic field is [Tesla].

Accordingly, the loop radiating element is characterized by having a low radial gain in the vertical direction and a high radial gain in the horizontal direction, as compared with a dipole or a folded dipole radiating element. It is possible to effectively absorb the idle electromagnetic wave while reducing the influence of the main radiating element.

Therefore, the loop radiating element has very suitable characteristics as the parasitic radiating element 120 for receiving the electromagnetic wave signal from the main radiating element 110 and collecting the energy. As can be seen in Figures 1 (a) and 1 (b), in one embodiment of the present invention, a rectangular loop radiating element printed on a substrate is used to place underneath the main radiating element 110, A slit 122 is formed in the inner substrate of the device so that the main radiating element 110 can be fed through the slit 122.

Fig. 1 (c) shows a detailed view of a parasitic radiating element having a two-turn loop structure printed on a dielectric substrate. Since the loop radiating element having a plurality of revolutions has a high quality factor (Q-factor) value when compared with the loop radiating element of a single number of revolutions, it can have a higher gain characteristic thereby, Bandwidth is reduced. That is, when the number of rotations of the loop radiating element is increased, the gain characteristic is increased. On the other hand, since the frequency bandwidth is reduced, the tradeoff relation is established. Therefore, in designing the parasitic radiating element 120, it is preferable to select the maximum number of revolutions so as to have higher gain characteristics among the number of revolutions that can include all the operating frequency bands.

In addition, the height of the parasitic radiating element 120, that is, the distance between the ground plane and the parasitic radiating element also affects the operation characteristics of the parasitic radiating element 120. FIG. 2 is a view for explaining the phenomenon of electromagnetic wave radiation of an ideal half-wave dipole radiating element on the ground plane 130 for explaining this. Since the half-wave dipole radiating element can be regarded as a part constituting the loop radiating element, the operation characteristics of the loop radiating element can be examined by examining this. As can be seen in FIG. 2, the vertical radiation pattern of the half-wave dipole radiating element determines the characteristics of the radiating element, such as the wave angle at which radiation occurs at maximum. 2 (b), the half-wave dipole radiating element emits the same energy in all directions. Ray analysis of the radio wave emitted from the radiating element, the same radio wave is radiated in the direction of A and the opposite direction of A ', and A' is again reflected by the ground plane 130 to A " Similarly, the same propagation of radiation in the direction of B and in the direction of B 'symmetrically with B is reflected by B' again by B 'by ground plane 130, And proceeds in the same direction. Accordingly, a phase difference between A and A "and a phase difference between B and B" become important factors for determining the radiation characteristic of the half-wave dipole radiating element. The phase difference can be determined by the difference in path length and the phase shift at the reflection point. Horizontally polarized electromagnetic waves exhibit a 180-degree phase shift due to reflection at an ideal ground (ideal ground) , So that the final phase difference between A and A "and the phase difference between B and B" will ultimately be determined by the height H of the half-wave dipole radiating element. If A and A "are in-phase at the height at which the half-wave dipole radiating element is located, the radiation intensity will be equal to the sum of both signals, The out-of-phase radiation intensity becomes smaller than the sum of the positive signals. Further, if the signals of the same magnitude have a phase difference of 180 degrees between A and A " Will be.

Accordingly, in one embodiment of the present invention, by adjusting the radiation characteristics while appropriately changing the height of the parasitic radiating element 120, it is possible to minimize the variation of the characteristics of the main radiating element 110, And a parasitic radiating element 120 having an optimized structure capable of efficiently collecting energy to be absorbed by the parasitic radiating element 120.

Embodiment 1. Design of an energy collection system 100 using a parasitic radiating element

As an embodiment of the present invention, an energy collection system operating in a frequency band of 2.13-2.15 GHz, which is one of the frequency bands used for WCDMA / LTE (Long Term Evolution) service in Korea, is designed below.

At this time, a Teflon substrate ( ? _R = 3.5, tan? = 0.0018, t = 0.78 mm And the width w ₁ and length l ₁ of the main radiating element 110 were designed in consideration of the radiation characteristics such as the resonance frequency a)).

On the other hand, in order to construct the parasitic radiating element 120, an FR4 substrate ( ? _R = 4.3, tan? = 0.02, t = 1 mm The width of the parasitic radiating element 120 (w) is set in consideration of the radiation pattern of the main radiating element 110. In this case, ₂ ) and the length ( ₁₂ ) were designed, and then the height was changed, the characteristics of the system according to the present invention were examined (FIG. 1 (b)). 1 (c), the first rotary loop of the parasitic radiating element 120 is connected to the first port of the second port cable 120. In this case, the first rotary loop of the parasitic radiating element 120 and the second rotary loop of the parasitic radiating element 120 are substantially the same length. The end point of which is connected to the second rotary loop via a through-hole, and the end point of the second rotary loop is connected to the ground pin (ground pin) 170 to the ground plane 130.

The height (h ₂ ) of the parasitic radiating element can be adjusted by a spacer 140 as shown in FIG. 1 (a). The main radiating element 110 passes through a rectangular slit 122 of the substrate of the parasitic radiating element 120 and is fixed to the center of the ground plane 130. With this structure, the size of the energy collecting system can be minimized, and furthermore, the present invention can be applied to an array antenna and the like, thereby suppressing interference signals between unit antennas and improving performance.

FIG. 3 shows a simulation result of the characteristic change of the main radiating element 110 according to the height of the parasitic radiating element 120. As shown in FIG. 3 (b), the resonant frequency of the parasitic radiating element 120 changed from 2.15 GHz to 2.20 GHz according to the change in height, and the return loss was greatly improved. 3 (a), the resonance frequency of the main radiating element 110 does not change much, but the return loss of the main radiating element 110 is slightly deteriorated . As can be seen from the simulation results, the higher the height of the parasitic radiating element 120, the greater the influence on the characteristics of the main radiating element 110 is. 3 (c) and 3 (d), as the height of the parasitic radiating element 120 increases, the coupling coefficient S21 between the main radiating element 110 and the parasitic radiating element 120 increases, The radiation gain of the radiating element 110 and the 3-dB beamwidth characteristic are reduced.

Table 1 below summarizes the simulation results. It can be seen from these results that the optimum value of the height of the parasitic radiating element 110 in this embodiment is 2 mm. In this case, the radiation gain of the main radiating element 110 is equal to the radiation gain of the parasitic radiating element 120 And the coupling coefficient S21 between the main radiating element 110 and the parasitic radiating element 120 is about -10.1 dB, which is relatively large Energy can be collected. The above simulation is performed using a commercial simulation tool, but the user can also perform a simulation by programming the numerical simulation directly.

Frequency [GHz] 2.100 2.150 2.200 S ₂₁ [dB] Gain [dB] Beam width [°] Gain [dB] Beam width [°] Gain [dB] Beam width [°] Main radiating element alone 8.5 85.8 8.3 88.3 7.9 92.9 - h ₂ = 1 mm 8.4 85.7 8.3 87.1 8.4 88.1 -15.0 h ₂ = 2 mm 8.5 85.3 8.1 86.8 7.7 88.7 -10.1 h ₂ = 3 mm 8.3 83.0 8.1 86.1 7.2 92.4 -6.4 h ₂ = 4 mm 8.3 84.9 8.0 86.0 6.4 87.2 -4.3 h ₂ = 5 mm 8.4 84.7 7.9 85.6 6.5 85.3 -3.7

Example 2 Fabrication and measurement of an energy collection system (100) using a parasitic radiating element

FIG. 4 shows photographs of an energy collection system 100 using a parasitic radiator fabricated as an embodiment of the present invention. At this time, the energy collecting antenna system is mainly composed of two parts, a main radiating element 110 and a parasitic radiating element 120. 4, the main radiating element 110 is vertically mounted at the center of the ground plane 130, and a rectangular slit 122, located at the substrate of the parasitic radiating element 120 at this time, So as to be assembled. As shown in FIG. 4 (b), the main radiating element 110 is connected to the first port, one end of the parasitic radiating element 120 is connected to the second port, and the other end is connected to the ground pin (170) to the metal ground plane (130). The ground plane 130 was 100 mm x 100 mm and a plastic support 140 was inserted at both ends of the parasitic radiating element 120 to adjust the height of the parasitic radiating element 120. 4C is a photograph of the energy collection system 100 using the parasitic radiating element according to an embodiment of the present invention finally assembled.

In order to verify the performance of the energy collecting system 100 using the parasitic radiator fabricated according to an embodiment of the present invention, various antenna characteristics were measured. FIG. 5 shows the reflection coefficient of the main radiating element and the parasitic radiating element according to the height of the parasitic radiating element. As can be seen in FIG. 5 (a), as the height of the parasitic radiating element increases from 2 mm to 5 mm, the reflection coefficient of the main radiating element appears to degrade, but still within the frequency band of 2.13 GHz to 2.17 GHz Lt; RTI ID = 0.0 > -10dB. ≪ / RTI > As the height of the parasitic radiating element 120 increases, the characteristics of the parasitic radiating element 120 improve. As shown in FIG. 5 (b), as the height of the parasitic radiating element 120 increases, It can be seen that the resonance characteristics are clearly shown in the case of FIG. When the height of the parasitic radiating element 120 is 2 mm, the reflection coefficient of the parasitic radiating element 120 exceeds 5 dB, which is the worst characteristic. On the other hand, the reflection coefficient of the main radiating element 110 is good . The result of the measurement is slightly different from the simulation result in FIG. 3 (b), which shows that in the fabrication of the parasitic radiating element 120, the ground pin 170 and the cable feeding It is judged to be due to manufacturing errors.

FIG. 6 (a) shows the coupling coefficient measurement between the main radiating element 110 and the parasitic radiating element 120. As can be seen, as the height of the parasitic radiating element 120 increases, the coupling coefficient between the main radiating element and the (110) parasitic radiating element 120 increases. When the height of the parasitic radiation 120 is 2 mm The coupling coefficient was measured to be about -12 dB. Conversely, it can be seen that the radiation gain of the main radiating element 110 is gradually lowered. The radiation gain when measured by the main radiating element 110 alone was 8.50 dBi and the radiating gain was 6.93 to 8.35 dBi depending on the height when the parasitic radiating element 120 was coupled. The maximum radiation gain was measured when the height of the parasitic radiating element 120 was 2 mm, where the 3 dB beamwidth was 87.1 degrees, which was slightly narrower than 88.6 degrees measured by the main radiating element 110 alone. Fig. 6 (d) shows the radiation pattern and the radiation gain on the E-plane (x-axis in Fig. 4 (c)) of the main radiating element 110. Fig. The above series of measurements was made in an anechoic chamber using an antenna measurement system. The measurement frequency is 2.15GHz, which is the center frequency of the operating frequency band.

In addition to the electrical characteristics test of the energy collecting system 100 using the parasitic radiator fabricated as an embodiment of the present invention, the EIRP (Effective Isotropically Radiated Power) Were measured. As shown in FIG. 7, a signal generator and a spectrum analyzer were arranged at a distance of 5 meters. Then, two standard horn antennas with a radiation gain of 10dBi are used, and a signal generator is used to generate a 10dBm signal at a frequency of 2.15GHz, which is then transmitted through a standard horn antenna using an RF cable having a loss of 0.75dB . The measured EIRP of the transmitter was 19.25dBm and the received power measured by the spectrum analyzer was -35.7dBm, resulting in a free space loss of 54.2dB.

Next, the standard horn antenna of the transmitting end is replaced with only the main radiating element 110 from which the parasitic radiating element 120 is removed in the energy collecting system 100 using the parasitic radiating element according to the present invention, and the remaining experimental conditions are the same . In this case, the measured received power was -37.45dBm, and the difference in received power was about -0.2dB, considering the radiation gain difference of 1.5dB of the antenna.

Finally, when the measurement is repeated in the energy collecting system 100 using the parasitic radiating element according to the present invention, the received power is -37.95 dBm, which is 0.6 dB lower than that of the standard horn antenna. In addition, the power of the electromagnetic wave received by the parasitic radiating element 120 was about -2.0 dBm, which is significantly higher than that of a typical signal receiver -40 dBm to -20 dBm . In addition, it can be seen that electromagnetic waves can be effectively collected and converted into electric power without deteriorating the characteristics of the main radiating element 110, as seen from the above experimental results. Table 2 below summarizes the measurement results of this experiment.

radiator Transmit antenna gain (A) [dBi] EIRP [dBm] FSL [dB] Received power (B) [dBm] Receive power difference [dB] for standard horn antenna Standard
Horn antenna 10.0 19.25


54.2 -35.70 - Main radiating element alone 8.5 17.70 -37.45 -0.2 The energy collection system 8.35 17.60 -37.95 -0.6

The present invention is not limited to an energy collection system in which a parasitic radiating element is disposed in close proximity to the main radiating element 110 which is previously viewed. That is, as another embodiment of the present invention, the system may be configured to collect the electromagnetic wave energy by arranging the loop radiating element close to a predetermined electromagnetic wave generating source other than the main radiating element.

According to another aspect of the present invention, there is provided an energy collecting system including a predetermined electromagnetic wave generating source, a parasitic radiating element disposed in proximity to the electromagnetic wave generating source, The loop radiating element can be used to construct an energy collection system.

Further, the electromagnetic wave generating source may include a ground plane, wherein the parasitic radiating element is disposed at a predetermined distance from the ground plane, wherein a distance from the ground plane of the parasitic radiating element is a distance Can be adjusted through experimentation or simulation so that the maximum energy can be collected from the electromagnetic wave generating source.

The characteristics such as the radiation pattern of the parasitic radiating element can be changed according to the distance between the parasitic radiating element and the ground plane.

Furthermore, it is preferable that the number of rotations of the loop radiating element includes a predetermined operating frequency band, and has a rotation number capable of maximizing the radiation gain of the loop radiating element.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention but to illustrate the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

100: Energy collection system using parasitic radiating element
110: main radiating element
120: Parasitic radiating element
122: slit
130: ground plane
140: Support
150: First port cable
160: Second port cable
170: ground pin

Claims (11)

A main radiating element formed on a first substrate having a directional radiation pattern and a predetermined operating frequency band;
A parasitic radiating element located behind the main radiating element and collecting energy radiated from the main radiating element in the same frequency band as the operating frequency band of the main radiating element; And
And a ground plane positioned below the main radiating element and the parasitic radiating element,
In this case, the parasitic radiating element is a loop radiating element formed on the second substrate, and the loop radiating element has the highest radiation gain characteristic among the rotational frequencies having the operating frequency band including the operating frequency band of the main radiating element The branch is made up of the number of revolutions,
Wherein a feed line for feeding the main radiating element is formed on the first substrate and a feed line of the first substrate is passed through a slit formed in the center of the loop radiating element of the second substrate to feed the main radiating element Energy collection system. The method according to claim 1,
The main radiating element comprises:
A monopole radiating element, a dipole radiating element, and a printed dipole radiating element. delete delete delete The method according to claim 1,
The parasitic radiating element includes:
Wherein the energy collection system has a length of a wavelength of an operating frequency or a circumferential length of an odd multiple thereof. The method according to claim 1,
The parasitic radiating element includes:
And a loop radiating element pattern formed on one or more layers of an upper layer, a lower layer, and an inner layer of the printed circuit board. 8. The method of claim 7,
The main radiating element comprises:
Characterized in that it is a printed dipole radiating element. delete delete delete

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