281 results about "Metamaterial antenna" patented technology

An efficient, low-loss, low sidelobe, high dynamic range phased-array radar antenna system is disclosed that uses metamaterials, which are manmade composite materials having a negative index of refraction, to create a biconcave lens architecture (instead of the aforementioned biconvex lens) for focusing the microwaves transmitted by the antenna. Accordingly, the sidelobes of the antenna are reduced. Attenuation across microstrip transmission lines may be reduced by using low loss transmission lines that are suspended above a ground plane a predetermined distance in a way such they are not in contact with a solid substrate. By suspending the microstrip transmission lines in this manner, dielectric signal loss is reduced significantly, thus resulting in a less-attenuated signal at its destination.

An efficient, low-loss, low sidelobe, high dynamic range phased-array radar antenna system is disclosed that uses metamaterials, which are manmade composite materials having a negative index of refraction, to create a biconcave lens architecture (instead of the aforementioned biconvex lens) for focusing the microwaves transmitted by the antenna. Accordingly, the sidelobes of the antenna are reduced. Attenuation across microstrip transmission lines may be reduced by using low loss transmission lines that are suspended above a ground plane a predetermined distance in a way such they are not in contact with a solid substrate. By suspending the microstrip transmission lines in this manner, dielectric signal loss is reduced significantly, thus resulting in a less-attenuated signal at its destination.

A metamaterial radome / isolator system includes a radiation source for providing a radiation beam through the radome / isolator having a frequency beyond the bandgap region where the metamaterial permittivity and permeability are both positive and the metamaterial medium has a low, matched relative permittivity and relative permeability.

The invention relates to a wave absorbing and transmitting integrated metamaterial radome and application thereof, belonging to the field of metamaterials. The radome comprises a dielectric structurelayer, a wave absorbing sandwich layer and a frequency selecting surface layer. The dielectric structure layer comprises first and second dielectric substrates, the first dielectric substrate is arranged on one side of the wave absorbing sandwich layer, the frequency selecting surface layer is arranged on the side of the wave absorbing sandwich layer away from the first dielectric substrate, and the second dielectric substrate is arranged on the side of the frequency selecting surface layer away from the wave absorbing sandwich layer. The radome is provided with a dielectric structure layer, awave absorbing sandwich layer and a frequency selecting surface layer, so that waves can be transmitted in the operating frequency band of the radome; at the same time, the frequency selecting surface reflects the out-of-band electromagnetic waves as a reflecting layer of the wave absorbing sandwich layer to achieve the purpose of absorbing waves, thereby realizing the stealth of a system using atransmitter and a receiver, such as a dual- (multi-) base station radar or space-based radar system. When the radome is used in optical imaging or miniaturized antennas or electromagnetic wave stealth, the wave absorbing and transmitting effect is obvious.

The invention belongs to the technical field of materials and radomes, and specifically relates to a single-passband bilateral wave-absorbing composite metamaterial and a radome and an antenna system including the same. The single-passband bilateral wave-absorbing composite metamaterial comprises a dielectric substrate (100) made of a non-conductive material and four periodic metamaterial structure layers embedded into the dielectric substrate. The four periodic metamaterial structure layers are respectively a resistive film layer (102), a first metal patch layer (103), a second metal patch layer (104) and a third metal patch layer (105) in sequence from top to bottom. The metal patch layers for realizing frequency selection enable an array antenna to keep good radiation characteristic and communicate freely in an X band; and meanwhile, in the S band, Ku band and K band at the two sides of the passband of the X band, the resistive film layer with wave absorption characteristic and the metal patch layers in the composite metamaterial radome work together, and electromagnetic wave which is incident on the radome and then reflected back by the metal patch layers is well absorbed.

The invention discloses a metamaterial antenna housing, including a polarization rotation metamaterial layer, a honeycomb structure layer and a frequency selection surface layer. The polarization rotation metamaterial layer includes a first dielectric substrate and a first metal structure layer; the frequency selection surface layer includes two second dielectric substrates, a second metal structure layer, a third metal structure layer and a fourth metal structure layer; and the first dielectric substrate and the second metal structure layer are attached to surfaces of two sides of the honeycomb structure layer respectively. Therefore, through arrangement of the polarization rotation metamaterial layer, the honeycomb structure layer and the frequency selection surface layer, the metamaterial antenna housing provided by the embodiment of the invention can realize efficient wave transmission of electromagnetic waves in a radome working band on the frequency selection surface, the metamaterial layer can be utilized to rotate the polarization direction of reflected electromagnetic waves out of the working band, mismatch of polarization modes of the reflected electromagnetic waves and energy detection electromagnetic waves is caused, thereby achieving the purpose of invisibility to an energy detection radar system, and thus the metamaterial antenna housing has important application prospects.

An antenna system may include a first metamaterial antenna having a first resonant frequency and a second metamaterial antenna having a second resonant frequency. The first resonant frequency may be different from the second resonant frequency. A first feed point may be connected to the first metamaterial antenna, and a second feed point may be connected to the second metamaterial antenna. A signal may be applied to the first and second feed points so that the first and second metamaterial antennas radiates electromagnetic energy while the signal is being applied and so that the antenna system is configured to send or receive signals over both the first and second resonant frequency bands.

The invention relates to a metamaterial antenna housing which comprises at least one metamaterial sheet layer, wherein each metamaterial sheet layer comprises a first substrate and a second substrate which are oppositely arranged, wherein at least one artificial micro structure is attached on the surface of the first substrate, which faces towards the second substrate, the artificial micro structure comprises four branches sharing an intersection joint, one end of any one branch is connected with the intersection joint, the other end of the branch is a free end, the branch comprises at least one bending part, and any branch sequentially clockwise rotates for 90 DEG, 180 DEG and 270 DEG with the joint as a rotating center and respectively coincides with other three branches. Through attaching the artificial micro structure with a special shape on the substrate, needed electromagnetic response is obtained, so that wave transparent performance of the metamaterial antenna housing is enhanced, and antijamming capability is increased.

The invention discloses a liquid crystal metamaterial antenna array for terahertz beam regulation and control, which comprises an upper quartz substrate, a lower quartz substrate, a metal metamaterialstructure grown on the upper quartz substrate, a metal grounding plane structure grown on the lower quartz substrate and a liquid crystal material sealed between the metal metamaterial structure andthe metal grounding plane structure. The invention further discloses a method for preparing the terahertz liquid crystal metamaterial antenna array and a beam regulation and control method and a characterization method by using the terahertz liquid crystal metamaterial antenna array. According to the invention, the dynamic regulation and control of terahertz beams within a certain angle space range are realized, the device is simple in structure, and the regulation and control method is flexible and convenient.

The invention discloses a feedback type microwave antenna, which comprises a radiation source, a first metamaterial panel used for diverging electromagnetic waves from the radiation source, and a second metamaterial panel with an electromagnetic wave converging function for converting the electromagnetic waves diverged from the first metamaterial panel into plane waves. The feedback type microwave antenna is fabricated based on a metamaterial principle to release from the limitation of conventional convex lens shapes, concave lens shapes and paraboloid shapes, can be planar or in any other shapes, thinner, smaller and more convenient to process and fabricate, and has the beneficial effects of low cost and good gain.

The invention provides a metamaterial antenna cover and an antenna system and relates to the technical field of metamaterials. The metamaterial antenna cover comprises two layers of dielectric substrates which are arranged in a stack manner and a first metal layer arranged between the two layers of dielectric substrates in a stack manner, wherein a second metal layer is respectively arranged between the first metal layer and each layer of the dielectric substrates in a stack manner; a first sandwich layer is further respectively arranged between the metal layer and each of the second metal layers in a stack manner; the first metal layer has a plurality of same hollows which are distributed at intervals; the second metal layers are mainly composed of a plurality of same metal patches; and metal patches of the second metal layers have an one-to-one correspondence with the hollows of the first metal layer. The antenna system comprises an antenna body and the metamaterial antenna cover which are arranged at intervals. Through the metamaterial antenna cover and the antenna system, which are provided by the invention, the wave transmission and the wave absorption are integrated and the purposes of carrying out high-efficiency wave transmission within a working frequency band and carrying out wave absorption outside the working frequency band are achieved.

The invention relates to a broadband metamaterial antenna housing and an antenna system. The broadband metamaterial antenna housing comprises at least one metamaterial sheet layer, wherein each metamaterial sheet layer comprises a first substrate and a plurality of artificial microstructures which are arranged on the first substrate in an array mode, and the sizes of the artificial microstructures are the same. Each artificial microstructure comprises a mouth-shaped structure, a snowflake-shaped structure is arranged at the center position of each mouth-shaped structure, and a T-shaped structure is arranged in the middle of each edge of each mouth-shaped structure. According to the broadband metamaterial antenna housing, the artificial microstructures in specific shapes are attached to the first substrates to obtain needed electromagnetic responses, wave-transparent performance of the antenna housing based on metamaterials is strengthened, and anti-interference capacity is increased. The working band of the antenna housing is 15-18GHz, wave-transparent efficiency within the band is high, and losses are fewer. The broadband metamaterial antenna housing has the band elimination characteristic when the working band is out of 15-18GHz, and selective filtering can be achieved.

The invention relates to a manufacturing method for a metamaterial antenna housing. The manufacturing method for the metamaterial antenna housing comprises the following of steps a, manufacturing a flexible thin metamaterial membrane provided with a plurality of artificial microstructures, b, manufacturing a die, wherein the die comprises a female die and a male die, the female die and the male die are mutually separated and can carry out relative movement to be combined in a closed mode, a concave cavity is formed by the female die, and a mold core which can be placed into the concave cavity is arranged on the male die in a protruding mode, c, placing the flexible thin metamaterial membrane in the concave cavity, attaching the flexible thin metamaterial membrane to the cavity wall, d, carrying out die assembly, placing the mold core of the male die into the concave cavity of the female die to form a die cavity, injecting a molten resin solution into the die cavity, and e, carrying out die disassembly after the resin solution is cooled and solidifies, and obtaining the metamaterial antenna housing which is provided with the artificial microstructures and is identical with the die cavity in shape. According to the manufacturing method for the metamaterial antenna housing, die cavities with different shapes can be manufactured to obtain various needed metamaterial antenna housings, and the artificial microstructures can be well arranged on the metamaterial antenna housing in a conformal mode.

The invention relates to a high-gain metamaterial antenna housing and an antenna system. The metamaterial antenna housing comprises at least one metamaterial slice layer, each metamaterial slice layer comprises a substrate and a plurality of artificial microstructures arranged on the substrate in an array mode; the artificial microstructures comprise four square-shaped structures arranged in an array mode, wherein a corner, close to the center of each artificial microstructure, of each square-shaped structure is provided with a notch. Needed electromagnetic response is obtained through the artificial microstructures in specific shapes and attached to the substrate. The relative dielectric constant, the refractive index and impedance of materials can be changed through regulation of the shapes and dimensions of the artificial microstructures, and directionality and grain of antennas are improved; under the condition of reaching the same grain, the array number of the antennas can be greatly reduced, and the overall size of the antennas is reduced. The space between the antenna housing and the antennas is little, the overall thickness is small, the number of layers of the metamaterial is regulated to control the grain of the antennas, user experience is improved, and different requirements of different customers for the grain of the antennas are met.

The invention relates to the size reduction of an antenna using a magneto-dielectric material for a CRLH-TL (Composite Right / Left Handed Transmission Line) antenna. In particular, the invention provides a small and low profile metamaterial antenna attained by performing SRR (Split Ring Resonator) magnetization on a dielectric material and applying the magneto-dielectric material to the CRLH-TL antenna that is composed of patches and vias. Even further, the invention provides a metamaterial antenna using a magneto-dielectric material, the antenna comprising: a substrate which is made up of a magneto-dielectric material and which has an SRR structure inserted thereto; patches with a CRLH-TL structure formed at a predetermined distance above the substrate; and a ground plane formed at a predetermined distance below the substrate.

A projector comprises a metamaterial antenna, a signal processing module and a projector optical system. The metamaterial antenna comprises a dielectric substrate, a feeding point which is arranged on the surface of the metamaterial antenna, a feeder liner which is connected with the feeding point and a metal structure. The feeder liner and the metal structure coupling with each other; the metamaterial antenna receives electromagnetic wave signals containing video and audio information, then switches the electromagnetic wave signals into electrical signals; the signal processing module is used for processing the electrical signals and generating result information; and the projector optical system responds to the result information and projects into images. The projector utilizes the built-in metamaterial antenna to transmit high speed, ultra wide band and high capacity video and audio information to the projector wirelessly and reduces the cost caused by installing different kinds of data interfaces greatly.

The invention provides a single-passband double-sided wave-absorbing metamaterial radome, an application thereof and an aircraft, and belongs to the technical field of radomes. The radome includes a plurality of square unit structures arranged successively and periodically, wherein each unit structure includes a dielectric layer, a reflective layer, and a wave-absorbing layer. In each unit structure, the reflective layer and the wave-absorbing layer are disposed on both sides of the dielectric layer respectively. The reflective layer is composed of a square ring and a square piece embedded therein. The wave-absorbing layer is formed by at least two octagonal ring structures embedded in one another. The mutually separate four sides of each octagonal ring structure are provided with openings. Chip resistors are disposed at the openings. The radome integrates wave transmission and stealth, and can absorb electromagnetic waves in non-wave-transmissive frequency bands to achieve a purpose of excellent transmission in the transmissive bands and high absorption in both side bands. The radome can be used as a radome at the antenna compartment in the aircraft such that the aircraft can achieve stealth in the wave-transmissive bands and absorb the waves in other bands, reducing the overall RCS of the aircraft.

The invention relates to a manufacturing method for a metamaterial board. The manufacturing method for the metamaterial board comprises the following steps of (1) using a piece of glass fiber cloth which has been dipped in a thermoset synthetic resin solution to manufacture a semi-solidified piece, (2) attaching a plurality of metal microstructures to the semi-solidified piece, (3) placing the semi-solidified piece with the attached metal microstructures between two pieces of glass fiber cloth with the thermoset synthetic resin solution in a dipping mode, and (4) carrying out heating and pressurization on the semi-solidified piece with the attached metal microstructures and the two pieces of glass fiber cloth with the thermoset synthetic resin solution in the dipping mode to combine the semi-solidified piece with the attached metal microstructures and the two pieces of glass fiber cloth with the thermoset synthetic resin solution in the dipping mode together in a pressing mode so as to obtain the metamaterial board. The manufacturing method for the metamaterial board is simple in process. Due to the facts that the metal microstructures are protected by the glass fiber cloth with thermoset synthetic resin, and the glass fiber cloth with the thermoset synthetic resin covers the two sides of each metal microstructure, abrasion cannot be easily caused, and good wave-transparent performance can be kept for a long time. The invention further relates to a metamaterial antenna housing made of the metamaterial board, and a manufacturing method for the metamaterial antenna housing.

The invention relates to a wideband-elimination metamaterial which comprises a metamaterial slice, the metamaterial slice comprises a media substrate and two structure layers which are attached to two opposite surfaces of the media substrate respectively, each structure layer comprises a plurality of regularly hexagonal metal micro-structures, the two metal micro-structures in the two structure layers, positioned at corresponding positions of the media substrate, form a pair, two adjacent sides of any two adjacent metal micro-structures in each structure layer are parallel to each other, so that the central interval of any two adjacent metal micro-structures is reduced, thus being capable of restraining electromagnetic wave in an ultrawide high frequency range so as to enable the metamaterials to have a wideband-elimination function; and the electromagnetic wave in low frequency range has the advantages of high wave transmittance and small reflection as well as good wave transmitting property. The invention further relates to a wideband-elimination metamaterial antenna housing and an antenna system which are produced by the wideband-elimination metamaterials.

The invention discloses a cassssegrain type metamaterial antenna. The antenna comprises a main metamaterial reflector with a central through-hole, a feed source which is arranged in a central through-hole and an auxiliary reflector which is arranged in front of the feed source, wherein electromagnetic waves radiated by the feed source are sequentially subjected to the reflection of the auxiliary reflector and the main metamaterial reflector and are ejected in a plane wave mode, the main metamaterial reflector comprises a core layer and a reflection layer which is arranged on rear surface of the core layer, the core layer comprises at least one core layer sheet layer, the core layer sheet layer comprises a base material and a plurality of artificial microstructures which are arranged on the base material, the auxiliary reflector is one of curved surfaces of a rotary ellipse surface, and a phase center of the feed source overlaps a far focus of the rotary ellipse surface. According to the cassssegrain type metamaterial antenna, a conventional paraboloid is replaced with the main metamaterial reflector in a sheet shape, and the antenna is easy to produce and process and low in cost.

The invention discloses an acoustic metamaterial. The acoustic metamaterial comprises Ng metamaterial units periodically distributed, wherein Ng is an integer greater than or equal to 3; and each metamaterial unit comprises a plurality of sub period units periodically distributed, each sub period unit comprises two piezoelectric elements, and the two piezoelectric elements on each sub period unitare connected with two branches of a negative capacitor. For the acoustic metamaterial, the Ng metamaterial units are periodically distributed, each metamaterial unit comprises a plurality of sub period units, the two piezoelectric elements of each sub period unit are connected with two branches of the negative capacitor, and therefore, by utilizing the piezoelectric metamaterial of a negative capacitor circuit network in pairing interconnection, the local-area resonance forbidden band gap with better attenuating property can be generated with fewer damping circuit branches of the negative capacitor and within the specific relatively wide frequency band, especially the lower frequency band.

The invention discloses a cassegrain metamaterial antenna, which comprises a rotary paraboloid, a feed source, a metamaterial and a hyperboloid, wherein the feed source is used for emitting electromagnetic waves; the metamaterial is arranged at a real focus of the hyperboloid, consists of a base material and a plurality of artificial micro structures on the base material and is used for scattering the electromagnetic waves to the hyperboloid; a virtual focus of the hyperboloid is overlapped with the focus of the rotary paraboloid and is used for reflecting the scattered electromagnetic waves to the rotary paraboloid; and the rotary paraboloid is used for sending the reflected electromagnetic waves to space in a manner of planar waves. According to the cassegrain metamaterial antenna, the electromagnetic waves emitted by the feed source pass through the metamaterial and are scattered to the hyperboloid at a certain angle and then reflected to the rotary paraboloid of the antenna through the hyperboloid, so that the influence of the feed source and a bracket thereof on the radiation of the antenna are greatly eliminated.

The invention relates to a metamaterial antenna which comprises a vibrator, a metamaterial film layer and a reflector, wherein the vibrator is used for generating electromagnetic waves; the metamaterial film layer is used for converging the electromagnetic waves generated by the vibrator and outwards radiating the electromagnetic waves and is also used for converting spherical electromagnetic waves generated by the vibrator into planar electromagnetic waves, and comprises a plurality of metamaterial sheet layers; and the reflector is used for reflecting partial electromagnetic waves generatedby the vibrator to the metamaterial film layer, is a cover-free cavity and forms a closed cavity together with the metamaterial film layer, and the vibrator is arranged in the reflector. Through changing the refractive index distribution condition inside the metamaterial film layer, the invention ensures that a half-power bandwidth of an antenna far field is reduced, further propagating distance of the antenna is increased, and front-to-back ratio of the antenna is increased.

The invention discloses a meta-material antenna housing. The meta-material antenna housing comprises a substrate with two side surfaces opposing to each other, and a plurality of artificial metal microstructures periodically distributed on the two opposing side surfaces. Each artificial metal microstructure comprises a first metal branch, a second metal branch and a third metal branch with both centers at the two ends of the first metal branch, fourth metal branches and fifth metal branches, wherein the second metal branch and the third metal branch are perpendicular to the first metal branch; the fourth metal branches perpendicularly extend either from the two ends of the second metal branch towards the direction of the third metal branch or from the two ends of the third metal branch towards the direction of the second metal branch; and each fifth metal branch perpendicularly extends from each fourth metal branch towards the direction of the first metal branch and the fifth metal branches and the first metal branch don't intersect. The meta-material antenna housing provided by the invention has a reflection coefficient S21 lower than that of a pure ABS material antenna housing by a decrease of 0.7 to 0.9 dB and a transmission coefficient S11 higher than that of the pure ABS material by an increase of 10 to 35 dB so that the electromagnetic performance of the antenna housing is greatly improved and the mechanical properties of the antenna housing are not damaged.

The invention relates to a metamaterial radome with a smoothing function and an antenna. The metamaterial radome comprises at least one metamaterial piece layer, each metamaterial piece layer comprises a substrate and a plurality of artificial microstructures of the same size arranged on the substrate in an array mode, and each artificial microstructure is of a circular ring structure. Due to the fact that the artificial microstructures of specific shapes are adhered to the substrates, needed electromagnetic response is obtained, and the radome based on a metamaterial has the certain smoothing function. The relative dielectric constant, the refractive index, impedance and the smoothing frequency band of the material are changed through changing of the shape and the size of the artificial metal microstructures, and limit for the thickness of the material and a dielectric constant when a traditional radome is designed is reduced. As for a double-frequency-point antenna or a multi-frequency-point antenna, mutual interference among multiple frequency points can be reduced by the adoption of the radome, and normal operation of the frequency points is guaranteed. In addition, the radome is quite thin, the overall size of the antenna is reduced, the weight of the antenna is reduced, and meanwhile installation and maintenance are facilitated.

The invention discloses a metamaterial antenna housing, which comprises a substrate and a plurality of artificial metal microstructures, wherein the substrate is provided with two opposite side surfaces, and the plurality of artificial metal microstructures are periodically arranged on the two opposite side surfaces. The substrate is virtually divided into a plurality of metamaterial units, and two opposite side surfaces of the metamaterial unit are both attached with one artificial metal microstructure. The artificial metal microstructure comprises an opening metal ring branch provided with an opening, and three straight line metal branches which are arranged inside the opening metal ring and share an endpoint, and an angle formed between two adjacent straight line metal branches is 120 degrees. The reflection coefficient S21 of the metamaterial antenna housing is 20-40dB higher than the transmission coefficient of an ABS material antenna housing, thereby greatly improving the electromagnetic performance of the antenna housing, and being capable of not damaging the mechanical performance of the antenna housing.

The invention provides a metamaterial base plate. Materials for preparing the metamaterial base plate include polystyrene and alumina fiber, wherein the alumina fiber accounts for 2 to 48 wt% of polystyrene. The invention also relates to a preparation method of the metamaterial base plate, and a metamaterial antenna prepared with the metamaterial base plate. The alumina fiber and polystyrene have low cost, and are simple in preparation technology, so the cost performance of the metamaterial base plate is high; the metamaterial base plate prepared with the alumina fiber serving as the filler of polystyrene has high heat resistance, low consumption and high strength; meanwhile, the metamaterial base plate is prepared with simple process and low cost; due to the high heat resistance, the metamaterial base plate can be applied to circuits with high temperature, high integrity level and high power; and the metamaterial base plate has low consumption and high strength, therefore, the requirement of the metamaterial antenna to the performance of the base plate can be met.

An encoded information reading (EIR) terminal can comprise a microprocessor electrically coupled to a system / data bus, a memory communicatively coupled to the microprocessor, an EIR device, a multi-band antenna, and a wireless communication interface. The EIR device can be provided by a bar code reading device, an RFID reading device, or a card reading device. The EIR device can be configured to output raw message data containing an encoded message and / or output decoded message data corresponding to an encoded message. The wireless communication interface can comprise a radio frequency (RF) front end electrically coupled to the multi-band antenna. The RF front end can comprise a micro-electromechanical (MEMS) filter array including one or more band-pass filter. Each band-pass filter of the MEMS filter array can be electrically coupled to a bias voltage source or an oscillating signal source. The RF front end can be electrically coupled to an analog-to-digital (A / D) converter and / or to a digital-to-analog (D / A) converter. The wireless communication interface can be configured to transmit radio signals in two or more frequency regulatory domains and / or receive radio signals in two or more frequency regulatory domains. The multi-band antenna can in one embodiment be provided by a meta-material antenna.

A shaped beam and multiple-input-multiple-output multi-antenna reuse switching system comprises a mode judging module, a switching module, a blocking factor (BF) transmitting module, a multiple-input-multiple-output (MIMO) multi-antenna reuse module, wherein the mode judging module used for judging whether a most suitable transmitting mode for a user is the shaped beam mode or the multiple-input-multiple-output multi-antenna reuse mode according to the switching algorithm, the switching module is used for deciding whether the shaped beam mode or the multiple-input-multiple-output multi-antenna reuse mode is adopted to transmit data information according to a result of mode judging modules, the BF transmitting mode is connected with the switching mode, and used for multiplying data with weight components of corresponding antenna and then retransmitting the data, and the MIMO multi-antenna reuse module is connected with the switching mode and used for carrying out MIMO code on the data, and transmitting the data after the MIMO code. The data information is transmitted in an electromagnetic mode outwards based on metamaterials composed of a plurality of metamaterial antenna units. The metamaterial array antennas are adopted to receive or transmit signals, and signal interference noise ratio of an entire system is improved, and interference of receiving or transmitting of environment signals is reduced.