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Phased Array: PHARRAY

Symbol

Summary

PHARRAY enables simulation of phased arrays with very large number of elements. It allows array configuration using various standard, as well as custom architectures. A number of commonly used gain tapers are implemented in this block, along with various signal distribution schemes and support for frequency-dependent operation. PHARRAY also allows you to simulate array imperfections due to manufacturing flaws or element failure.

Phased Array Settings

You can configure the phased array on the Element Options dialog box Phased Array Settings tab.

Array Setup

This section defines the main configuration parameters for PHARRAY.

Operation mode: Set to either TX or RX modes. In TX mode, the signal power exciting each element is calculated based on the Operation mode setting. In RX mode, all elements are assumed to be exposed to the same signal power.

Signal distribution: Valid only when Operation mode is set to TX. In this case, the available options are:

  • Lossless - all array elements are excited by the same power, equal to the power of the input signal.

  • Power Divider - the input signal is divided equally among all array elements such that the sum of their powers equals the power of the input signal.

  • Voltage Divider - the input signal is divided equally among all array elements such that the sum of their voltages equals the input signal.

Distance units: The units used in defining the array geometry. The available options are centimeters, feet, inches, lambda, meters, yards. If distance units are set to anything but lambda (signal wavelength), the Signal frequency should be defined; in this case, the array response is frequency-dependent.

Signal frequency: The carrier frequency of the signal at the phased array. This option is ignored if Distance units is set to lambda. NOTE: If the frequency is defined as a numerical value, it uses the project frequency units; if it is defined as a variable, it is interpreted in Hz.

Steering Angle

This section defines the steering angles for the phased array. The Theta (angle off boresight) and Phi (azimuth) are used to steer the array response. If left empty, they are set to 0 internally.

NOTE: If angles are defined as numerical values, they use the project angle units; if they are defined as variables, they are interpreted in Rad.

Angle of Incidence

This section defines the angle of incidence for the signal transmitted/received by the phased array. The Theta and Phi define the angle where the signal power is measured for TX operations, and the angle from where the signal is received for RX operations.

Array Geometry

The PHARRAY block offers several options for defining the array architecture:

  • Lattice - allows configuration of the phased array in a lattice pattern, which is configured using the number of elements along the X and Y axes, NX and NY, element spacing along these axes, dx and dy, and Gamma, the angle between these axes. Setting Gamma to 90° results in a rectangular lattice, while setting it to 60° creates a triangular lattice. Any positive value for Gamma may be used to configure the lattice.

  • Circular - enables configuration of circular phased arrays with one or more concentric circles. The number of elements in each concentric circle and the radius of each circle can be defined as vectors by variables NC and R. Variable Phi_0 defines the angular offset of the first element in each circle from the X axis; if Phi_0 is 0, the first element of the circle is placed on the X axis.

  • User defined - allows definition of your own array architecture, using the number of array elements, N, and their X/Y locations defined by vectors X loc. and Y loc.. These vectors should have at least N elements.

Gain Taper

This section allows you to define a gain taper for use in the phased array.

Gain taper coefficient handling defines whether the gain taper is normalized or not. If it is, the taper is normalized to unit gain.

Standard allows the use of standard gain tapers implemented in PHARRAY:

  • Dolph-Chebyshev - the taper is calculated using the Dolph-Chebyshev technique and is configured by defining the SLR (side lobe ratio) in dB. If the array is planar, you can define the taper Alignment, that is, whether the taper is calculated along the X axis, Y axis, or as a multiplication of tapers calculated along each axis.

  • Taylor - the taper is calculated using the Taylor technique and is configured using SLR and Alignment parameters similar to Dolph-Chebyshev.

  • Uniform - the taper uses equal-gain taps for all the array elements.

User defined - allows the use of custom gain tapers by defining Gains (dB) and Phases for each array element. The Gains and Phases vectors should contain at least as many elements as the size of the phased array.

Array Imperfections

This section allows modeling of manufacturing flaws, gain/phase offsets due to nonlinearities and/or quantization errors, as well as element failure.

Offsets can be used to define any difference from the nominal X/Y locations of the array elements. These offsets are defined using the units specified in Distance units.

Gain offsets (dB) allows modeling of gain offsets from the ideal gain taper levels. This option may be used to model element-specific gain variation.

Phase offsets allows modeling of phase offsets due to quantization errors and/or other imperfections in the phased array.

Element failure allows modeling of deterministic or random element failure:

  • None - no failed elements are modeled, phased array operates normally.

  • Specific - a specific set of elements is disabled during simulation. These elements are defined in Failed elements.

  • Random - a percentage of the total number of elements is randomly selected and disabled. The percentage of elements is defined in Failure rate as a %. The options in the Diagnostics to Display section may be used to display which elements were disabled during the simulation.

Diagnostics to Display

This section allows display of diagnostic information that is created during simulation. If such information is available, it is displayed in a separate window that opens during simulation.

  • None - no information displays.

  • Full - all available diagnostic information displays.

  • Element X/Y Locations - X and Y locations of array elements display. The distance units are included in this information. X and Y locations display as two separate vectors, which you can use for plotting the array element geometry in the NI AWR Design Environment suite or any other tool.

  • Gain Taper - the gain taper coefficients display as a vector, in dB.

  • Failed Elements - the indexes of the failed elements display.

See Phased Arrays and MIMO Arrays in the VSS Modeling Guide for more information on working with phased arrays and MIMO arrays.

Parameters

Name Data Type Description Unit Type Default
ID N Element ID   A1
*MODE E Array operation mode (TX or RX)   TX
*SIGDSTR E Signal distribution type for TX arrays   Lossless
THETA R Angle of incidence in relation to Z-axis Degree  
PHI R Angle of incidence on XY plane, in relation to X-axis Degree  
THETA_ST R Steering angle in relation to Z-axis Degree  
PHI_ST R Steering angle on XY plane, in relation to X-axis Degree  
*FRQ R Signal frequency (if empty, use CTRFRQ) GHz  
*ARRAYGEOM E Array geometry   Lattice
*NX I Number of phased array columns (along X axis)   1
*NY I Number of phased array rows (along X axis)   1
*DX R Element distance along X axis   0.5
*DY R Element distance along Y axis   0.5
*GAMMA R Angle between X and Y axes Rad _PI/2
*NC I Number of elements in circular phased array (use vectors for concentric circles)   1
*R R Radius of circular phased array (use vectors for concentric circles)   0.5
*PHI0 R Offset angle of circular phased array (use vectors for concentric circles) Deg  
*N I Number of elements in user-defined phased array    
*XLOC R X location of each antenna element    
*YLOC R Y location of each antenna element    
*DISTUNIT E Distance units used for X and Y locations   lambda
*ZINP C Input port characteristic impedance (if empty, set to 50 for TX, 377 for RX) Ohm  
*ZOUT C Output port characteristic impedance (if empty, set to 377 for TX, 50 for RX) Ohm  
*GAINTAPER E Use standard or user-defined gain taper   Standard
*TAPERCOEFFS E Gain taper coefficient handling   Normalized
*TAPERTYPE E Standard gain taper type   Uniform
*SLR R Side lobe ratio (for the Dolph-Chebyshev and Taylor gain tapers) dB 40
*TAPERALIGN E Taper alignment   X
*TAPERUPDATE E Taper update frequency   Once
*GAINS R Gain coefficients for each element dB  
*PHASES R Phase coefficients for each element Deg  
*XOFFSET R Offsets from nominal X locations    
*YOFFSET R Offsets from nominal Y locations    
*GOFFSET R Gain offsets from nominal values dB  
*PHOFFSET R Phase offsets from nominal values Deg  
*EFFAIL E Element failure type   None
*ELFAILVEC I Vector of failed elements (indices, 0-based)    
*ELFAILPCT R Percentage of failed elements    
*ELFAILSEED I Random number generator seed for random element failure    
*DIAGDSP E Diagnostics to display   None

* indicates a secondary parameter

Parameter Details

MODE. Define TX or RX operation mode.

SIGDSTR. Signal distribution scheme used in TX mode.

THETA. Angle of incidence: angle off boresight.

PHI. Angle of incidence: azimuth.

THETA_ST. Angle of incidence: angle off boresight.

PHI_ST. Angle of incidence: azimuth.

FRQ. Signal frequency. Used when array geometry is defined in metric or imperial units. If empty, the propagated value for CTRFRQ is used.

ARRAYGEOM. Array geometry used: "Lattice", "Circular", or "User defined".

NX. Number of elements along the X axis in the lattice phased array.

NY. Number of elements along the Y axis in the lattice phased array.

DX. Element spacing along X axis.

DY. Element spacing along Y axis.

GAMMA. Angle between X and Y axes in the lattice configuration.

NC. Number of elements in each concentric circle of the circular phased array.

R. Radius of each concentric circle of the circular phased array.

PHI0. Offset angle of each concentric circle of the circular phased array.

N. Number of elements in the user-defined phased array.

XLOC. X locations of elements in the user-defined phased array.

YLOC. Y locations of elements in the user-defined phased array.

DISTUNIT. Distance unit used in defining X and Y locations of array elements.

ZINP. Input port characteristic impedance. If left empty, ZINP is set to 50 ohm for TX operation and to 377 ohm (free-space impedance) for RX operation.

ZOUT. Output port characteristic impedance. If left empty, ZOUT is set to 377 ohm (free-space impedance) for TX operation and to 50 ohm for RX operation.

GAINTAPER. Define whether standard or user-defined gain tapers are used.

TAPERCOEFFS. Gain taper coefficient handling, defines whether gain taper is normalized or not.

TAPERTYPE. Gain taper type.

SLR. Side lobe ratio used in configuring Dolph-Chebyshev and Taylor gain tapers.

TAPERALIGN. Taper alignment used for planar tapers. This setting has no effect for linear arrays. For lattice planar arrays, the gain taper may be calculated along the X axis, along the Y axis, or along both axes and the product of the latter is used.

TAPERUPDATE. Taper update frequency. If set to "Once", taper is calculated once and is used for the duration of the simulation. If set to "Continuous", gain taper is calculated each time a new sweep is started.

GAINS. Gain coefficient for each element when a user-defined taper is used.

PHASES. Phase offsets for each element when a user-defined taper is used.

XOFFSET. Offsets from nominal X locations when array imperfections are modeled.

YOFFSET. Offsets from nominal Y locations when array imperfections are modeled.

GOFFSET. Gain offsets from nominal values.

PHOFFSET. Phase offsets from nominal values.

EFFAIL. Element failure type.

ELFAILVEC. Vector of failed elements when Specific element failure type is selected.

ELFAILPCT. Percentage of failed elements when Random element failure type is selected.

ELFAILSEED. The seed for the random number generator used to shuffle which elements actually fail when element failure type is Random.

If this is left empty, a seed is generated based on a hash of the block name and the ID parameter (if the block is within a subcircuit, the ID parameters of the parents are also used). In general, this results in different instances of the block generating different sequences, although it is not guaranteed.

DIAGDSP. Diagnostic information to display.

Data Input

Port No. Type Purpose
1 Unset Input Signal

Data Output

Port No. Type Purpose
2 Unset Output signal

Implementation Details

PHARRAY enables simulation of phased arrays with very large numbers of elements. The signal distribution to elements of a TX phased array and signal combining from array elements of an RX phased array is performed internally, leading to computationally efficient implementation.

PHARRAY allows you to use standard array geometries to facilitate the phased array configuration, especially when a large number of elements are used. The supported configurations are standard lattice and circular geometries. For lattice geometry, the phased array is configured by defining the number of elements along the X and Y axes, the element spacing dx and dy, as well as the angle between the X and Y axes. An example of a triangular lattice array is shown in the following figure:

The circular phased arrays are configured by defining the number of array elements in each concentric circle, as well as the radius of each circle and their angular offset from the X axis. The following figure shows an example of a circular array.

The response of the phased array may be modified using standard gain tapers, such as Dolph-Chebyshev and Taylor, as well as user-defined tapers.

PHARRAY also provides the ability to simulate array imperfections due to manufacturing flaws or element failure. Offsets from X and Y nominal elements may be defined. Also, gain and phase offsets from the ideal values may also be defined. The element failure may be defined as a percentage of the total number of elements, which is randomly selected during simulation, as well as a specific set of elements. You may find useful the secondary parameter TAPERUPDATE when random failed elements are modeled - this parameter defines the update frequency of the taper and failed elements. When TAPERUPDATE is set to "Once", the failed elements and gain taper are updated only once during the simulation. This is useful when the same failed elements should be simulated for a variety of angles or other swept variables. However, to average over various failure patterns, you can set the TAPERUPDATE to "Continuous", in which case different failed elements are used during each variable sweep.

The phased array can display various diagnostic information that can be useful for further processing. This information contains X/Y locations of phased array elements, which may be used to visually display the phased array geometry, the calculated gain tapers, and the failed elements, which can be useful for identifying the specific failed elements when they are selected randomly.

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