KR20210152381A - Optical beamforming device using phased array antenna and operating method thereof - Google Patents

Abstract

The present disclosure relates to an optical beamforming device using a phased array antenna and an operating method thereof. According to an embodiment of the present disclosure, the optical beamforming device comprises: an RF frontend for transceiving RF signals; and an optical beamformer for compensating or forming a time relay for a plurality of channels on the basis of the RF signals. The optical beamformer includes: E/O converters for converting the RF signals to optical signals; a linear modulator for generating an optical modulation signal on the basis of an RF input signal; a TTD array for outputting an optical combination signal in which the time delay of the input optical signals is compensated, or outputting output optical signals formed with the time delay for each of the channels by distributing the optical modulation signal; a photodetector for generating an RF output signal to an RF backend on the basis of the optical combination signal; and E/O converters for converting the optical signals to the RF signals. Accordingly, the optical beamforming device capable of beamforming regardless of bandwidth is provided.

Description

Optical beamforming device using phased array antenna and operating method thereof

The present disclosure relates to an optical beamforming apparatus and an operating method thereof, and more particularly, to an optical beamforming apparatus using a phased array antenna for forming or compensating for a time delay for each channel in a TTD method, and an operating method thereof will be.

In the recently developed 5G+ wireless communication technology, research on phase array antennas is being actively conducted to expand superband, ultra-low latency, and super connectivity. A phased array antenna is an antenna capable of scanning a beam in various directions by electrically controlling a phase difference between a plurality of antennas. Beamforming or beamshaping refers to a function of electrically controlling a phase difference by forming or shaping a wavefront of a beam. A beamformer or a beamshaper that performs a beamforming or beamforming function can quickly and stably scan the direction of a beam, so it has been used in communication and military radars, and recently also used in smart antennas.

A method of implementing the beamforming function may be divided into a phase shifting (PS) method and a true time delay (TTD) method. The PS method has a problem in that a beam squint phenomenon occurs due to a dispersion characteristic that varies according to a frequency, so that it is difficult to apply to a field requiring wideband operation and abrupt frequency change.

The TTD method is a method of forming a phase difference by differentiating the start points of the phases using a time delay difference of a signal. A configuration of a beamforming apparatus using a general TTD scheme can be divided into a ring resonator-based configuration and a distributed configuration using a multi-wavelength light source and a WDM scheme. The ring resonator-based configuration has problems in that the bandwidth is limited to several GHz and the delay time is relatively short as several ns. A distributed configuration using a multi-wavelength light source and WDM method has problems such as complicated structure, difficult integration, and high production cost.

SUMMARY OF THE INVENTION An object of the present disclosure is to provide an optical beamforming apparatus using a phased array antenna and an operating method thereof, in which beamforming is possible regardless of bandwidth and the configuration and operation are simple.

An optical beamforming apparatus according to an embodiment of the present disclosure includes an RF front end for receiving a plurality of RF antenna input signals or transmitting a plurality of RF antenna output signals using a phased array antenna having a plurality of channels, and the plurality of an optical beamformer for compensating or forming a time delay for each of the plurality of channels based on RF antenna input signals or an RF input signal from an RF backend, wherein the optical beamformer includes the plurality of RF antenna input signals a plurality of E/O converters configured to convert the optical signals into a plurality of input optical signals, a linear modulator generating an optical modulated signal based on an RF input signal from the RF backend, and compensating for a time delay degree of the input optical signals A TTD array for outputting one optical combined signal or outputting output optical signals having a time delay for each channel by distributing the optical modulated signal, and generating an RF output signal to the RF backend based on the optical combined signal a photodetector that does this, and a plurality of E/O converters configured to convert the output optical signals to the plurality of RF antenna output signals.

A method of operating an optical beamforming apparatus according to an embodiment of the present disclosure includes: linearly modulating, by a linear modulator, an RF antenna input signal to an optical signal based on an RF antenna input signal received from an RF backend; generating a plurality of optical distribution signals in which the optical signal is distributed to a plurality of TTD elements for each channel using generating output optical signals delayed by a delay time required in a channel in real time, a plurality of O/E converters converting the output optical signals into RF antenna output signals, respectively, and a plurality of antenna elements using the RF and radiating the antenna output signals to the outside.

The method of operating an optical beamforming apparatus according to an embodiment of the present disclosure includes the steps of: individual antennas receiving respective RF antenna input signals for each channel from the outside, and a plurality of E/O converters receiving the RF antenna input signals respectively. converting the signals into signals, the TTD array generating optical compensation signals that compensate for the delay time of the input optical signals based on the electrical control signal, the TTD array using a power combiner to generate the optical compensation signal generating an optical combined signal obtained by combining them, and a balance detector generating an RF output signal to an RF backend based on the optical combined signal.

According to the present disclosure, since the optical path and time delay are determined regardless of the wavelength or frequency of the beam, beamforming without bandwidth limitation can be performed.

According to an embodiment of the present disclosure, the operation and control are easy with the same time delay for each unit cell constituting the TTD device, and since it is implemented in the form of a chip, it can be integrated with peripheral devices.

1 is a conceptual diagram of beamforming according to an embodiment of the present disclosure.
2 is a configuration diagram schematically showing an optical beamforming apparatus according to an embodiment of the present disclosure.
3 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 2 in more detail.
4 is a configuration diagram showing a configuration of the TTD array 1240 shown in FIG. 3 according to an embodiment.
5 is a block diagram illustrating unit cells constituting the TTD device shown in FIGS. 2 to 3 .
6 is a configuration diagram showing the configuration of the TTD device shown in FIGS. 2 to 3 in more detail.
7 is an exemplary flowchart of a case in which a phased array antenna transmits a signal in an optical beamforming method according to an embodiment of the present disclosure.
8 is an exemplary flowchart of a case in which a phased array antenna receives a signal in an optical beamforming method according to an embodiment of the present disclosure.

Below, embodiments of the present disclosure will be described clearly and in detail to the extent that those skilled in the art can easily practice the present disclosure.

1 is a conceptual diagram of beamforming according to an embodiment of the present disclosure. The optical beamforming apparatus 1000 according to an embodiment of the present disclosure may use a linear phased array antenna (PAA). The optical beamforming apparatus 1000 transmits an output signal based on an input signal from an RF back-end (RF_BE), or an output signal to an RF back-end (RF_BE) based on an input signal received from the outside. can transmit For convenience of description, it is assumed that an output signal is transmitted based on an input signal from a radio frequency back-end (RF_BE).

For example, a linear phased array antenna may include n antenna elements. Here, n is a natural number of 2 or more. The n antenna elements may form respective channels. For example, if the linear phased array antenna includes 10 antenna elements, 10 channels may be formed. The optical beamforming apparatus 1000 may radiate an output signal in the form of an electromagnetic wave in a desired direction through each channel based on an input signal in the form of an electric signal received from the RF backend RF_BE. For example, the optical beamforming apparatus 1000 may differently set delay times of each channel by using a true time delay (TTD) method. The optical beamforming apparatus 1000 may change the radiation direction of the linear phased array antenna by using the phase start point difference according to the delay time of each channel.

The output signal of the optical beamforming apparatus 1000 may be in a state having a specific phase front. For example, a state having a specific phase plane may correspond to State 0, State 1, ... , State k according to the radiation angle of the linear phased array antenna, and is not limited to the radiation angle shown in FIG. 1 . Here, k is 0 or any natural number. For example, when the output signal of the optical beamforming apparatus 1000 is State 0, the phase front at State 0 of the output signal may be a plane perpendicular to the D2 direction, and the radiation direction of the signal is on the phase plane. It may be in the vertical D2 direction. Here, the D1 direction is the direction of an arbitrary vector on an arbitrary plane. When the output signal of the optical beamforming apparatus 1000 is State 1, the phase front at State 1 of the output signal is parallel to the D1 direction and the direction having an angle difference _{of α 1 in a clockwise or counterclockwise direction.} and the radiation direction of the signal may be a direction perpendicular to the phase plane. In the same principle, when the output signal of the optical beamforming device 1000 is State k, the phase front of the output signal (Phase front at State k) is an angle difference _{by α k in the D1 direction and in the clockwise or counterclockwise direction.} It may be parallel to the direction with which the signal has, and the radiation direction of the signal may be a direction perpendicular to the phase plane.

In order to specify the phase plane of the signal, delay times of channels of the optical beamforming apparatus 1000 may be set differently. For example, when the unit delay time is defined as Δτ, the real-time delay (TTD_CHn) of the channel n may follow the relationship of Equation 1.

Referring to Equation 1, n is defined as a continuous order of each channel, and t _n is defined as a delay time of the n-th channel, channel n. k is defined as a specific state (eg, State 0, State 1, ... , State k) of an output signal of the optical beamforming apparatus 1000 . Δτ is defined as unit delay time. For example, the real-time delay (TTD_CHn) of the channel n may be determined as k*(n-1)*Δτ according to Equation (1). For example, the real-time delay (TTD_CH2) of the channel 2 may be determined as k*1*Δτ. As a result, the optical beamforming apparatus 1000 may radiate an output signal having a specific phase plane based on successive real-time delays of each channel.

The optical beamforming apparatus 1000 may linearly rotate the phase plane to have a discrete time delay as shown in FIG. 1 . According to an exemplary embodiment of the present disclosure, the optical beamforming apparatus 1000 may non-linearly control the time delay of each channel for fine adjustment of the output signal. For example, although not shown, the optical beamforming apparatus 1000 may further include a phase tuner (PT) for nonlinear control of a time delay.

2 is a configuration diagram schematically showing an optical beamforming apparatus according to an embodiment of the present disclosure. The optical beamforming apparatus 1000 may include a radio frequency front-end 1100 and an optical beamformer 1200 . The optical beamforming apparatus 1000 according to an embodiment of the present disclosure may transmit and/or receive a signal. Accordingly, the optical beamforming apparatus 1000 may be configured to perform both a transmission function and a reception function in each antenna element, as shown in FIG. 2 . However, although not shown, the optical beamforming apparatus 1000 may be configured such that each antenna element performs at least one of a transmission function and a reception function.

The RF front end 1100 may include antenna elements 1110_1 to 1110_n, first circulators 1120_1 to 1120_n, LNAs 1130_1 to 1130_n, and PAs 1140_1 to 1140_n. The RF front end 1100 may transmit an output signal to the outside or receive an input signal from the outside using a phased array antenna having a plurality of channels. Furthermore, the RF front-end 1100 may amplify power before transmitting an output signal to the outside, or may amplify while minimizing noise of a signal after receiving an external input signal.

Each of the antenna elements 1110_1 to 1110_n _{radiates an electromagnetic wave to the outside based on each RF antenna output signal RF out_1} to RF _{out_n} in the form of an electric signal, or an RF antenna input signal in the form of an electric signal based on an external electromagnetic wave It is possible to receive the _{RF in_1} to RF _{in_n .} The first circulators 1120_1 to 1120_n are three-port irreversible electronic devices, and each of the antenna elements 1110_1 to 1110_n receives each of the RF antenna input signals RF _{in_1} to RF _{in_n} from the outside to the LNAs (low). pass to noise amplifiers 1130_1 to 1130_n, or to pass respective RF antenna output signals RF _{out_1} to RF _{out_n} from power amplifiers (PAs) 1140_1 to 1140_n to respective antenna elements 1110_1 to 1110_n can The LNAs 1130_1 to 1130_n may amplify noise of each of the RF antenna input signals RF _{in_1} to RF _{in_n} while minimizing noise. The PAs 1140_1 to 1140_n may generate respective RF antenna output signals RF _{out_1} to RF _{out_n} by amplifying the RF signal for external transmission.

Optical beamformer 1200 includes E/O converters 1210_1 to 1210_n, O/E converters 1220_1 to 1220_n, second circulators 1230_1 to 1230_n, TTD array 1240, and third circulator 1260 ), a photodetector 1270 , and a linear modulator 1280 . The optical beamformer 1200 converts an RF signal into an optical signal and delays the optical signal in real time in a TTD method to form or compensate for a phase start point difference of the signal for each channel.

The E/O converters 1210_1 to 1210_n are respectively output optical signals OF based _{on the respective RF antenna input signals RF in_1} to RF _{in_n} and the first optical reference signal OF _{LD1 amplified by the LNAs. in_1} to OF _{in_n} ) may be generated. Here, the first optical reference signal OF _LD1 may be generated by the first laser diode LD1 (not shown). For example, the first laser diode LD1 may be located outside. In this case, the first laser diode _{LD1 may be connected to the LD1 node N LD1 to transmit the first optical reference signal OF LD1} to the E/O converters 1210_1 to 1210_n. However, unlike illustrated, the first laser diode LD1 may be included in the optical beamforming apparatus 1000 to transmit the first optical reference signal OF _LD1 to the E/O converters 1210_1 to 1210_n.

For example, the E/O converters 1210_1 to 1210_n use the first optical reference signal OF _LD1 to optically modulate each of the RF antenna input signals RF _{in_1} to RF _{in_n to electrically-} Electro-optic transformation may be performed. According to an exemplary embodiment of the present disclosure, the E/O converters 1210_1 to 1210_n may include Mach-Zehnder modulators (MZM) for optical modulation of electrical signals. As a result, the E/O converters 1210_1 to 1210_n may generate respective input optical signals OF _{in_1} to OF _{in_n} .

The O/E converters 1220_1 to 1220_n may generate respective RF antenna output signals RF _{out_1} to RF _{out_n based on the respective output optical signals OF out_1} to OF _{out_n} . According to an exemplary embodiment of the present disclosure, the O/E converters 1220_1 to 1220_n may include a photo detector (PD) for electrical modulation of an optical signal. Here, the photodetector has a configuration separate from the photodetector 1270 shown in FIG. 2 .

The second circulators 1230_1 to 1230_n transfer each of the input optical signals OF _{in_1} to OF _{in_n} from the E/O converters 1210_1 to 1210_n to the TTD array 1240 , or each of the output optical signals OF _{out_1} to OF _{out_n} ) may be transferred from the TTD array 1240 to the O/E converters 1220_1 to 1220_n.

_{The TTD array 1240 generates an optical combine signal OF out_TTD} based on at least a portion of the plurality of input optical signals OF _{in_1} to OF _{in_n} , or each output optical signal based on the optical modulation signal OF _{in_TTD} Signals OF _{out_1} to OF _{out_n} may be generated. For example, the TTD array 1240 may be controlled by an electric control signal ECS, and may compensate or form a time delay based on a transmission/reception signal of each channel. Accordingly, the TTD array 1240 may compensate for or form a phase start point difference by varying the degree of real-time delay for each channel. A specific configuration and operation of the TTD array 1240 will be described with reference to FIGS. 3 to 4 .

The electrical controller 1250 may control the operation of the TTD array 1240 . For example, the electrical controller 1250 may control an optical switch (hereinafter, OSW) included in the TTD array 1240 by transmitting the electrical control signal ECS to the TTD array 1240 . The electrical controller 1250 may control the degree of real-time delay formed by the TTD array 1240 by controlling the OSW. A specific operation of the electric controller 1250 will be described with reference to FIGS. 5 to 6 .

The third circulator 1260 transfers the optical combine signal OF _{out_TTD} from the TTD array 1240 to the optical detector 1270 , or transfers the optical modulated signal OF _{in_TTD} from the linear modulator 1280 to the TTD array 1240 . can be transmitted as According to an exemplary embodiment of the present disclosure, the optical beamformer 1200 may further include a single side band filter (hereinafter referred to as SSBF). The SSBF may be located between the TTD array 1240 and the photo detector 1270 and/or between the TTD array 1240 and the linear modulator 1280 . SSBF may suppress signal distortion by filtering the optical combine signal OF _{out_TTD} and/or the optical modulation signal OF _{in_TTD .}

The photodetector 1270 may generate _{an RF output signal RF out_B} to the backend based on the _{optical combine signal OF out_TTD} and the first optical reference signal OF _LD1 . The photodetector 1270 may transmit the RF output signal RF _{out_B} to the backend to the backend input node N _B1 connected to the RF backend. For example, the photo detector 1270 may be configured as a photo diode (PD). According to an exemplary embodiment of the present disclosure, the photodetector 1270 detects correlated noise from the _{optical combine signal OF out_TTD} and the first optical reference signal OF _{LD1 through differential amplification.} By removing it, it is possible to perform balanced detection that improves a signal-to-noise ratio (SNR).

The linear modulator 1280 may generate the optical modulation signal OF _{in_TTD based on the RF input signal RF in_B} and the second optical reference signal OF _LD2 from the backend. The linear modulator 1280 may be connected to the backend output node N _{B2 connected to the RF backend to receive the RF input signal RF in_B} from the backend, which is an output signal of the RF backend. Also, the linear modulator 1280 may be connected to the LD2 node N _LD2 connected to the second laser diode LD2 to receive the second optical reference signal LD2 . According to an exemplary embodiment of the present disclosure, the second laser diode LD2 may be located outside or may be included in the optical beamforming apparatus 1000 differently from the illustration. According to an exemplary embodiment of the present disclosure, the linear modulator 1280 may perform a single-side band operation.

3 is a configuration diagram showing the configuration of the TTD array 1240 shown in FIG. 2 in more detail. The TTD array 1240 may include a power splitter/combiner 1241 and TTD elements 1242_1 to 1242_n.

The power splitter/combiner 1241 may operate as a power splitter when the _{optical modulation signal OF in_TTD is received.} In this case, the power splitter/combiner 1241 is each TTD connected to the respective channels (eg, channel 1 ( FIG. 1 , CH1 )) ports PA1 to PAn based on the _{optical modulation signal OF in_TTD .} Each of the light distribution signals OF _{in_TTD_1} to OF _{in_TTD_n} may be transmitted to the devices 1242_1 to 1242_n. Furthermore, the power splitter/combiner 1241 may operate as a power combiner when receiving the _{plurality of optical compensation signals OF out_TTD_1} to OF _{out_TTD_n .} In this case, the power splitter/combiner 1241 transmits the optical combine signal to the output port PB of the TTD array 1240 based on at least a part of the _{plurality of optical compensation signals OF out_TTD_1} to OF _{out_TTD_n} OF _{out_TTD} ) can be transmitted.

For example, the power splitter/combiner 1241 may be implemented in the form of an optical fiber or an optical waveguide. For example, when the power splitter/combiner 1241 is in the form of an optical waveguide, the power splitter/combiner 1241 includes silica (SiO ₂ ), silicon (Si), amorphous silicon ( amorphous silicon), silicon nitride (SiNx), or silicon oxynitride (SiON).

The TTD elements 1242_1 to 1242_n generate optical compensation signals OF _{out_TTD_1} to OF _{out_TTD_n based on the respective input optical signals OF in_1} to OF _{in_n} from the respective channel ports PA1 to PAn, or , on the basis of the respective light distribution signal (oF _{in_TTD_1} to _{in_TTD_n} oF) to produce a respective output light signal (oF oF _{out_1} to _{out_n)} it can be transmitted with each channel port (PA1 to PAn). For example, each of the TTD elements 1242_1 to 1242_n may compensate for or form a phase start point difference by varying the degree of real-time delay with respect to the input signals, and then output the same. The electrical controller 1250 may adjust the degree of real-time delay of signals input to each of the TTD elements 1242_1 to 1242_n through each of the electrical control signals ECS ₁ to ECS _{n .} According to an exemplary embodiment of the present disclosure, the electrical control signal ECS (eg, ECS ₁ ) may include a plurality of control signals. A detailed configuration and operation of each of the TTD elements 1242_1 to 1242_n will be described with reference to FIGS. 5 to 6 .

4 is a configuration diagram showing a configuration of the TTD array 1240 shown in FIG. 3 according to an embodiment. FIG. 4 shows that some components are added to the TTD array 1240 shown in FIG. 3 , and signal notations are omitted in FIG. 4 for simplicity of illustration. The TTD array 1240 according to an embodiment of the present disclosure may further include amplifiers 1243_1 to 1243_n and attenuators 1244_1 to 1244_n. The amplifiers 1243_1 to 1243_n and the attenuators 1244_1 to 1244_n may amplify or attenuate the intensity of signals input/output through the TTD. The amplifiers 1243_1 to 1243_n and the attenuators 1244_1 to 1244_n are not limited to the connection relationship shown in FIG. 4 , and as long as they amplify or attenuate the strength of signals input or output to the TTD array 1240 , the TTD It may be located arbitrarily within the array 1240 . Although not shown, the TTD array 1240 may further include a phase tuner (PT) for non-linear fine phase adjustment.

5 is a block diagram illustrating unit cells constituting the TTD device shown in FIGS. 2 to 3 . Each of the TTD elements ( 1242_1 to 1242_n in FIG. 3 ) may include a plurality of unit cells 1242_u . The unit cell 1242_u of the TTD device may include a 1x2 optical switch (OSW) and a 2x1 optical combiner (OC). For example, OSW is implemented with a compound semiconductor material such as indium phosphide (InP) or gallium arsenide (GaAs), or in the form of a polymer total internal reflection (TIR) switch. can be implemented.

The unit cell 1242_u is based on the electrical control signal ECS from the electrical controller 1250 _{compared to the signal input to the input port P in_u of the} unit cell compared to the output port P _{out_u} of the unit cell. It may be delayed or not delayed by the unit delay time Δτ. Here, the electrical control signal ECS constitutes any one of the plurality of electrical control signals ( FIG. 3 , ECS ₁ to ECS _n ) input to any one of the plurality of TTD elements ( FIG. 3 , 1242_1 to 1242_n ). means each electrical control signal input to each unit cell. For example, an electrical control signal input to the TTD element 1242_2 of the channel 2 ( FIG. 3 , 1242_2 ) is ECS ₂ , and ECS ₂ is composed of electrical control signals input to each unit cell 1242_u in the TTD element. Since the unit cell 1242_u _{is configured non-reciprocal with respect to the input port (P in_u} ) of the unit cell and the output port (P _{out_u} ) of the unit cell, the signal is transmitted from the input port (P _{in_u} ) of the unit cell It should be input to the unit cell 1242_u.

_{When the signal input from the input port (P in_u} ) of the unit cell is input to the x node (N _x ) of the OSW, the OSW is the y1 node according to the on/off state of the electrical control signal (ECS) of the electrical controller 1250 (N _y1 ) or node y2 (N _y2 ) can be connected to node x (N _{x ).} Here, the on/off state of the electrical control signal ECS determines whether the signal is delayed by a unit delay time Δτ. For example, if the electrical control signal (ECS) is in the off state, the electrical control signal (ECS) does not indicate a time delay, in this case, the x node (N _x ) of the OSW is the y1 node ( N _y1 ) is connected. On the other hand, if the electrical control signal ECS is on, the electrical control signal ECS indicates a time delay, and OSW is y2 connected to the second path longer than the first path to be delayed by a unit delay time Δτ. Can switch to node N _{y2 .} However, the connection relationship of the OSW according to the on/off state of the electrical control signal ECS is not limited to that described above, and the opposite relationship (eg, when the electrical control signal ECS is turned off, is connected to the y2 node, When the electrical control signal ECS is on, connected to the y1 node) may be followed. The OC may be configured to connect the first path and the second path.

6 is a configuration diagram showing the configuration of the TTD device shown in FIGS. 2 to 3 in more detail. Referring to FIG. 6 together with FIG. 5 , the TTD element 1242 may include a plurality of unit cells 1242_u. Since the unit cell 1242_u of FIG. 5 and the unit cell of FIG. 6 are substantially the same, reference numbers and signal notations of the unit cell of FIG. 6 are omitted for simplicity of illustration. Each unit cell constituting the TTD element 1242 may be controlled by a plurality of electrical control signals ECS from the electrical controller 1250 . When the electrical control signal ECS is in the on state, it is assumed that the unit cell delays the signal by the unit delay time Δτ. If the number of OSWs receiving the on-state electrical control signal ECS is defined as M, the total delay time of the signal by the TTD element 1242 can be calculated as M*Δτ. Here, the OSW inside the TTD element 1242 If the number of is defined as m and the number of channels is defined as n, m is greater than or equal to n-1, and M may correspond to any integer between 0 and m.

Since the unit cell is configured as non-reciprocal with respect to the input port (P _{in_u} ) and the output port (P _{out_u} ) of the unit cell, it is composed of a plurality of unit cells (Unit Cell) The TTD element 1242 is also configured to be irreversible with respect to the _{input port (P in} ) and the output port (P _{out ).} Accordingly, although not shown, the optical beamforming apparatus 1000 according to an exemplary embodiment of the present disclosure configures TTD elements for transmission and reception differently. For example, the TTD device for transmission receives each of the optical distribution signals OF _{in_TTD_1} to OF _{in_TTD_n from the input port P in} , and receives each of the output optical signals OF _{out_1} to OF _{out_n} to the output port P _{out .} ) can be printed. For example, the TTD device for reception receives the input optical signals OF _{in_1} to OF _{in_n from the input port P in} , and receives the respective optical compensation signals OF _{out_TTD_1} to OF _{out_TTD_n} to the output port P _{out .} ) can be printed.

7 is an exemplary flowchart of a case in which a phased array antenna transmits a signal in an optical beamforming method according to an embodiment of the present disclosure. For convenience of description, FIG. 7 is described with reference to the reference numerals of FIGS. 1 to 3 .

In step S110 , the linear modulator 1280 receives the RF input signal RF _{in_B} from the backend received from the RF backend and the RF input signal RF _{in_B} from the backend based on the second optical reference signal OF _LD2 . It can be linearly modulated with an optical signal.

In step S120 , the TTD array 1240 distributes the TTD input optical signal OF _{in_TTD} , which is a linearly modulated optical signal, to the TTD elements 1242_1 to 1242_n for each channel by using a power splitter to each optical distribution signal. The ones OF _{in_TTD_1} to OF _{in_TTD_n} may be generated.

In step S130 , the TTD array 1240 transmits each of the optical distribution signals OF _{in_TTD_1} to OF _{in_TTD_n} based on the electrical control signal ECS from the electrical controller 1250 as required in each channel CH1 to CHn. It can be delayed in real time as much as the delay time. Here, the delay time required for each channel CH1 to CHn follows the relationship of Equation 1 described above.

In operation S140 , the O/E converters 1220_1 to 1220_n may convert each of the output optical signals OF _{out_1} to OF _{out_n} output by the TTD array 1240 for each channel into an RF signal.

In step S150, the antenna elements 1110_1 to 1110_n are converted RF signals, each of the RF antenna output signals (RF _{out_1} to RF _{out_n} ) to a specific state (eg, State 0, State 1, ... , State k) It is possible to radiate a signal in the form of an electromagnetic wave having a phase plane of .

8 is an exemplary flowchart of a case in which a phased array antenna receives a signal in an optical beamforming method according to an embodiment of the present disclosure. For convenience of explanation, FIG. 8 is described with reference to the reference numerals of FIGS. 1 to 3 .

In step S210, the antenna elements 1110_1 to 1110_n constituting the phased array antenna receive a signal in the form of an external electromagnetic wave having a phase plane of a specific state (eg, State 0, State 1, ... , State k). It can be received in the form of a signal.

In step S220 , the E/O converters 1210_1 to 1210_n convert each of the RF antenna input signals RF _{in_1} to RF _{in_n} received by the antenna elements 1110_1 to 1110_n to the respective input optical signals OF which are optical signals. _{in_1} to OF _{in_n} ).

In operation S230 , the TTD array 1240 may compensate for a delay time for _{each of the input optical signals OF in_1} to OF _{in_n} based on the electrical control signal ECS from the electrical controller 1250 . Here, the delayed time follows the relationship of Equation 1 described above.

_{In step S240 , the TTD array 1240 combines the optical compensation signals OF out_TTD_1} to OF _{out_TTD_n} which are output signals of the TTD elements 1242_1 to 1242_n for each channel by using a power combiner to combine the optical combine. A de-signal OF _{out_TTD} may be generated.

In operation S250 , the balance detector 1270 may detect the RF signal based on the _{optical combine signal OF out_TTD} and the first optical reference signal OF _{LD1 . The RF output signal RF out_B} to the backend that is the detected RF signal may be output to the RF backend.

The above are specific examples for carrying out the present disclosure. The present disclosure will include not only the above-described embodiments, but also simple design changes or easily changeable embodiments. In addition, the present disclosure will also include techniques that can be easily modified and implemented in the future using the above-described embodiments. Therefore, the scope of the present disclosure should not be limited to the above-described embodiments and should be defined by the claims described below as well as the claims and equivalents of the present disclosure.

1000: optical beamforming device 1100: RF front end
1110_1 to 1110_n: antenna elements
1120_1 to 1120_n: first circulators
1130_1 to 1130_n: LNAs
1140_1 to 1140_n: PAs 1200: optical beamformer
1210_1 to 1210_n: E/O converters
1220_1 to 1220_n: O/E converters
1230_1 to 1230_n: second circulators
1240: TTD Array 1241: Power Splitter/Combiner
1242: TTD element
1242_1 to 1242_n: TTD elements 1242_u: unit cell
1250: electrical controller 1260: third circulator
1270: photodetector 1280: linear modulator

Claims (17)

In the optical beamforming apparatus,
an RF front end that receives a plurality of RF antenna input signals or transmits a plurality of RF antenna output signals using a phased array antenna having a plurality of channels; and
an optical beamformer for compensating or forming a time delay for each of the plurality of channels based on the plurality of RF antenna input signals or an RF input signal from an RF backend;
The optical beamformer,
a plurality of E/O converters configured to convert the plurality of RF antenna input signals into a plurality of input optical signals;
a linear modulator for generating an optically modulated signal based on an RF input signal from the RF backend;
a TTD array for outputting an optical combine signal compensating for the time delay of the input optical signals or outputting output optical signals having a time delay for each channel by distributing the optical modulation signal;
an electrical controller for generating an electrical control signal for controlling the degree of time delay;
a photodetector for generating an RF output signal to an RF backend based on the optical combine signal; and
and a plurality of E/O converters configured to convert the output optical signals into the plurality of RF antenna output signals. The method of claim 1,
The RF front end,
a plurality of antennas for receiving the plurality of RF antenna input signals for the plurality of channels or for transmitting a plurality of RF antenna output signals; and
An optical beamforming apparatus comprising a plurality of amplifiers for removing and amplifying noise of the plurality of RF antenna input signals or the plurality of RF antenna output signals. The method of claim 1,
An optical beamforming apparatus for the TTD array to discretely determine a time delay degree according to Equation 1 below with respect to the plurality of channels.
Equation 1:

(However, n: successive sequence of individual channels, t _n : delay time of channel n, k: state numerical value according to the phase plane rotation angle of the signal, an integer greater than or equal to 0, Δτ: unit delay time) The method of claim 1,
The TTD array is
A plurality of optical compensation signals obtained by compensating time delay for the plurality of channels are generated based on the plurality of input optical signals, or a time delay of the plurality of channels is generated based on a plurality of optical distribution signals. a plurality of TTD elements generating the plurality of output optical signals; and
When the optical modulation signal is input, the plurality of optical distribution signals for the plurality of channels are generated by operating as a power splitter, and when the plurality of optical compensation signals are input, it operates as a power combiner. An optical beamforming device comprising a power splitter/combiner for generating an optical combined signal. 5. The method of claim 4,
Each of the plurality of TTD elements includes a plurality of unit cells,
The unit cell is
When the electrical control signal does not indicate a time delay, it switches to a first node connected to a first path, and when the electrical control signal indicates a time delay, a second path longer than the first path is delayed by a unit delay time. an optical switch for switching to a second node connected to the second path; and
An optical beamforming apparatus including an optical combiner connecting the first path and the second path. 5. The method of claim 4,
The TTD array is
An optical beamforming apparatus further comprising at least one of an attenuator and an amplifier for adjusting the intensity of input and output signals. 5. The method of claim 4,
The TTD array is
The optical beamforming apparatus further comprising a phase tuner for non-linearly adjusting the phases of input and output signals. 5. The method of claim 4,
The power splitter/combiner is an optical beamforming device implemented in the form of an optical fiber or an optical waveguide. 9. The method of claim 8,
The power splitter/combiner implemented in the form of the optical waveguide is an optical beamforming device implemented with a material of silica, silicon, amorphous silicon, silicon nitride, or silicon oxynitride. 6. The method of claim 5,
The optical switch and the optical combiner are optical beamforming apparatus implemented in the form of an optical waveguide. 11. The method of claim 10,
The optical switch is an optical beamforming device implemented with a compound semiconductor material including InP or GaAs. 11. The method of claim 10,
The optical switch is an optical beamforming device implemented in the form of a polymer total reflection switch. The method of claim 1,
The photodetector is an optical beamforming device for removing correlation noise through differential amplification. The method of claim 1,
The optical detector is an MZM optical detector. The method of claim 1,
The optical beamforming apparatus further comprising a single sideband band filter connected to at least one of between the TTD array and the photodetector and between the TTD array and the linear modulator. In the method of operation when the optical beamforming device transmits an RF signal to the outside,
linear modulating the RF antenna input signal into an optical signal based on the RF antenna input signal received from the RF backend by a linear modulator;
generating, by the TTD array, a plurality of optical distribution signals obtained by distributing the optical signal to a plurality of TTD devices for each channel using a power splitter;
generating, by the TTD array, output optical signals in which the plurality of optical distribution signals are delayed by a delay time required for each channel in real time based on an electrical control signal;
converting the output optical signals into RF antenna output signals by a plurality of O/E converters; and
and a plurality of antenna elements radiating the RF antenna output signals outward. In the method of operation when the optical beamforming device receives an RF signal from the outside,
individual antennas receiving respective RF antenna input signals for each channel from the outside;
converting the RF antenna input signals into input optical signals, respectively, by a plurality of E/O converters;
generating, by the TTD array, optical compensation signals for compensating for a delay time of the input optical signals based on the electrical control signal;
generating, by the TTD array, an optical combined signal obtained by combining optical compensation signals using a power combiner; and
and a balanced detector generating an RF output signal to an RF backend based on the optical combine signal.

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