bistaticFreeSpacePath

Bistatic free space propagation path

Since R2025a

Syntax

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,tgtPoses)

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,tgtPoses,Name=Value)

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,Name=Value)

Description

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,tgtPoses) returns bistatic free space propagation paths in the direction of the receiver and target.

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,tgtPoses,Name=Value) returns bistatic free space propagation paths in the direction of the receiver and target, with additional options specified using one or more name-value arguments. For example, you can specify transmitter and receiver mounting locations and angles.

propPaths = bistaticFreeSpacePath(freq,txPose,rxPose,Name=Value) returns only the direct path when IncludeDirectPath is set to the default value of true. The direct path is the path from the transmitter to the receiver.

Examples

Bistatic Free Space Propagation Paths

This example shows how to calculate the free space propagation paths for a bistatic transmitter and receiver with one target.

Create a bistatic scenario with a bistatic transmitter and receiver separated by 2 km. Place a target in the y-direction 5 km away. Calculate the bistatic free space paths. There are two paths. The first path is the direct path (transmitter-to-receiver). The second path is the bistatic path (transmitter-to-target-to-receiver).

Define the transmitter position, receiver position, target position, and target velocity. The target is located 5 km away and is moving at 20 m/s in the y-direction. Calculate the bistatic free space propagation paths.

freq             = 300e6;
txPose.Position  = [-1e3 0 0]; % Transmitter position (m)
rxPose.Position  = [1e3 0 0];  % Receiver position (m)
tgtPose.Position = [0 5e3 0];  % Target position (m)
tgtPose.Velocity = [0 20 0];   % Target velocity (m/s)
proppaths = bistaticFreeSpacePath(freq,txPose,rxPose,tgtPose)

proppaths=1×2 struct array with fields:
    PathLength
    PathLoss
    ReflectionCoefficient
    AngleOfDeparture
    AngleOfArrival
    DopplerShift

Bistatic Free Space Propagation Direct Path

This example shows how to calculate the direct bistatic free space propagation path. The direct path is the path between the transmitter and receiver.

Create a bistatic scenario with a bistatic transmitter and receiver separated by 2 km.

Define the transmitter position and receiver position. Calculate the direct bistatic free space propagation path.

freq             = 300e6;
txPose.Position  = [-1e3 0 0]; % Transmitter position (m)
rxPose.Position  = [1e3 0 0];  % Receiver position (m)
proppaths = bistaticFreeSpacePath(freq,txPose,rxPose)

proppaths = struct with fields:
               PathLength: 2000
                 PathLoss: 88.0108
    ReflectionCoefficient: 1
         AngleOfDeparture: [2×1 double]
           AngleOfArrival: [2×1 double]
             DopplerShift: 0

Input Arguments

freq — Operating frequency (Hz)

positive scalar

Operating frequency of the transmitter and receiver, specified as a positive scalar in units of hertz.

Data Types: double

txPose — Transmitter platform pose

structure

Transmitter platform pose, specified as a structure that contains Position, Velocity, Orientation, and Signatures fields. The Signatures field contains the monostatic RCS, and the bistatic RCS is derived using the Monostatic-Bistatic Equivalence Theorem (MBET) approximation. You can define platforms as platform objects in a radarScenario and then return the platform position (does not include Signatures) as structures using platformPoses. The Signatures field in txPose is not used and is an optional input.

Field	Description
Position	Position of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are in meters (m). There is no default value.
Velocity	Velocity of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are meters per second (m/s). The default value is [0 0 0].
Orientation	Orientation of the platform with respect to the local scenario navigation frame, specified as a unitless scalar quaternion or a 3-by-3 rotation matrix in units of degrees. Orientation defines the frame rotation from the local navigation coordinate system to the current platform body coordinate system. Units are dimensionless. The default value is quaternion(1,0,0,0).
Signatures	Mean monostatic target radar cross section (RCS) signature, specified as a rcsSignature object. Polarimetric signatures are not supported. The default value is the rscSignature object with default values.

Data Types: struct

rxPose — Receiver platform pose

structure

Receiver platform pose, specified as a structure that contains Position, Velocity, Orientation, and Signatures fields. The Signatures field contains the monostatic RCS, and the bistatic RCS is derived using the Monostatic-Bistatic Equivalence Theorem (MBET) approximation. You can define platforms as platform objects in a radarScenario and then return the platform position (does not include Signatures) as structures using platformPoses. The Signatures field in rxPose is not used and is an optional input.

Field	Description
Position	Position of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are in meters (m). There is no default value.
Velocity	Velocity of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are meters per second (m/s). The default value is [0 0 0].
Orientation	Orientation of the platform with respect to the local scenario navigation frame, specified as a unitless scalar quaternion or a 3-by-3 rotation matrix in units of degrees. Orientation defines the frame rotation from the local navigation coordinate system to the current platform body coordinate system. Units are dimensionless. The default value is quaternion(1,0,0,0).
Signatures	Mean monostatic target radar cross section (RCS) signature, specified as a rcsSignature object. Polarimetric signatures are not supported. The default value is the rscSignature object with default values.

Data Types: struct

tgtPoses — Target platform poses

structure | 1-by-T array of structures

Target platform poses, specified as a structure or a 1-by-T array of structures that contain Position, Velocity, Orientation, and Signatures fields for each target, T. The Signatures field contains the monostatic RCS, and the bistatic RCS is derived using the Monostatic-Bistatic Equivalence Theorem (MBET) approximation. You can define platforms as platform objects in a radarScenario and then return the platform position (does not include Signatures) as structures using platformPoses.

Field	Description
Position	Position of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are in meters (m). There is no default value.
Velocity	Velocity of the platform, specified in the global coordinate frame as a real-valued 1-by-3 row vector in the form of [x y z]. Units are meters per second (m/s). The default value is [0 0 0].
Orientation	Orientation of the platform with respect to the local scenario navigation frame, specified as a unitless scalar quaternion or a 3-by-3 rotation matrix in units of degrees. Orientation defines the frame rotation from the local navigation coordinate system to the current platform body coordinate system. Units are dimensionless. The default value is quaternion(1,0,0,0).
Signatures	Mean monostatic target radar cross section (RCS) signature, specified as a rcsSignature object. Polarimetric signatures are not supported. The default value is the rscSignature object with default values.

Data Types: struct

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: propPaths = bistaticFreeSpacePath(txPose,rxPose,tgtPoses,IncludeDirectPath=false)

TransmitterMountingLocation — Transmitter position offset (m)

[0 0 0] (default) | 1-by-3 vector

Offset of the transmitter origin relative to the Position of the txPose platform, specified as a 1-by-3 vector in the form of [x y z], in units of meters. The default value is [0 0 0].

Data Types: double

ReceiverMountingLocation — Receiver position offset (m)

[0 0 0] (default) | 1-by-3 vector

Offset of the receiver origin relative to the Position of the rxPose platform, specified as a 1-by-3 vector in the form of [x y z], in units of meters. The default value is [0 0 0].

Data Types: double

TransmitterMountingAngles — Transmitter mounting angles (deg)

[0 0 0] (default) | 1-by-3 vector

Transmitter mounting angles relative to the Orientation of the txPose platform, specified as a 1-by-3 vector in the form of Euler angles around [z y x] axes, in units of degrees. These angles are also referred to as [yaw pitch roll]. The default value is [0 0 0].

Data Types: double

ReceiverMountingAngles — Receiver mounting angles (deg)

[0 0 0] (default) | 1-by-3 vector

Receiver mounting angles relative to the Orientation of the rxPose platform, specified as a 1-by-3 vector in the form of Euler angles around [z y x] axes, in units of angles. These angles are also referred to as [yaw pitch roll]. The default value is [0 0 0].

Data Types: double

IncludeDirectPath — Enable direct path propagation

true or 1 (default) | false or 0

Enable direct path propagation, specified as a logical 0 (false) or 1 (true). If IncludeDirectPath is set to true, the propagation paths also include the path from the transmitter to the receiver. If IncludeDirectPath is set to false, the propagation paths only include the paths from the transmitter to the target to the receiver. The default value is true.

Data Types: logical

PropagationSpeed — Signal propagation speed (m/s)

physconst('LightSpeed') (default) | positive scalar

Signal propagation speed, specified as a positive scalar. Units are in meters per second (m/s). The default propagation speed is the value returned by physconst('LightSpeed'). See physconst for more information.

Example: 3e8

Data Types: double

Output Arguments

propPaths — Propagation paths

1-by-P array of structures

Returns bistatic free space propagation paths in the direction of the receiver and target or the direct path between the transmitter and receiver. propPaths is a 1-by-P array of path configuration structures, where P is the number of propagation paths. Propagation paths are in the radar mounting frame. Each propPaths structure describes a propagation path and contains these fields.

Field	Description
PathLength	Propagation path length, specified as a nonnegative scalar in units of meters (m).
PathLoss	Propagation loss along the path, specified as a scalar in units of decibels (dB).
ReflectionCoefficient	Cumulative reflection coefficients for all reflections along the path, specified as a scalar in linear units. The coefficients include effects like reflections from a scatterer or a target. Note, the bistatic RCS used in the ReflctionCoefficient calculation is derived using the Monostatic-Bistatic Equivalence Theorem (MBET) approximation.
AngleOfDeparture	Propagation path angle of departure, specified as a two-element vector in the form of [azimuth; elevation] in units of degrees (deg). The angle of departure is determined in the transmit antenna mounting frame.
AngleOfArrival	Propagation path angle of arrival, specified as a two-element vector in the form of [azimuth; elevation] in units of degrees (deg). The angle of arrival is determined in the receive antenna mounting frame.
DopplerShift	Cumulative Doppler shift along the path, specified as a scalar in units of hertz (Hz).

Version History

Introduced in R2025a