Multifunction Radar

A multifunction radar models multiple radar beams working together at the same location. Each beam has its own power specs and constraints.

Beams
Pointing
Location
Transmitter
Receiver
Jamming
Clutter
Detection Processing
Waveform Strategy Settings

Beams

The Beams tab provides a summary of the parameter values set for each beam, including:

BeamID. This is an alphanumeric name that identifies the beam.
Gain. All beams are modeled as Pencil Beam antennas with a user-specified gain. The default value is 40 dB. Side lobes are automatically computed based on the beamwidth and the maximum gain of the Main Lobe.
Beam Width. All beams are modeled as Pencil Beam antennas with a user-specified beam width. The default value is 1.62062 deg.
PointingType. This can be Targeted, Fixed Orientation, or Spinning.
PointingTypeSummary. This field provides the azimuth and elevation of the pointing vector.

Beam summary table

You can add, duplicate, and remove beams from the Beam summary table.

You can edit property values for a beam in the table or in the Waveform and Pointing tabs beneath the table. The table is automatically updated with your changes.

At any instant in time, the total power of all beams active at that time cannot exceed the maximum power limit of the radar system. Note that when dual channel operation is enabled (primary and orthogonal polarization), the power need of each beam is double that of a single channel operation.

Subtabs for Beams

When you select the Beams tab, the following subtabs appear below the summary table.

Active Times
Beam Spec
Pointing
Waveforms

Active Times

From the Beams tab, click the Active Times tab to reveal a drop-down menu with the following options:

Active Times Setting	Description
Always Active	Beam is always active.
Always Inactive	Beam is never active.
Time Components	Click Add to create or select a Time Component from the Select Component window. The beam will be active during the time component's start and stop times. You can only add interval or interval list time components to the this table.
Time Intervals	Click Add, Load..., or Import... to insert a time interval. The start and stop times specified in this table define the time intervals when the beam is active. Each row defines one interval. The Active column enables you to apply or disable intervals without needing to delete and recreate them. The interval includes the start time but not the stop time. Click Remove to delete the selected row or Remove All to clear the table.

Beam specifications

From the Beams tab, click the Beam Spec tab to see the following options:

Beam Spec Parameter	Description
Beam Width	All beams are modeled as Pencil Beam antennas with a user-specified beam width. The default value is 1.62062 deg.
Gain	All beams are modeled as Pencil Beam antennas with a user-specified gain. The default value is 40 dB. Side lobes are automatically computed, based on the beamwidth and the maximum gain of the Main Lobe.

Pointing (Individual Beam)

From the Beams tab, click the Pointing subtab to define the pointing type.

Pointing Type	Description
Targeted	The beam will point to a single object. Click the arrow buttons to move selected objects between the Available Targets and Assigned Targets lists. The beam will point to the object in the Assigned Target list.
Fixed Orientation	The beam will point from a specific orientation. Select an option from the Orientation Method menu. Enter values that define the orientation in the selected method.
Spinning	The radar beam will spin on its axis or sweep in a defined pattern. Select an option from the Orientation Method menu. Enter values that define the spin axis orientation in the selected method. The Cone Angle is the angle between the spin axis and the antenna boresight. As the boresight spins about the spin axis, it maintains this angular distance away from the spin axis. The Spin Rate is the rate at which the boresight spins about the spin axis. The spin is positive in a right-handed sense about the spin axis. You can enter a negative rate to create a spin in the opposite direction. The Azimuth Offset defines the plane in the parent object's body-fixed frame in which the antenna boresight lies. It is the angle between the X axis and the azimuth vector in the XY plane. An offset of 0 degrees means that the antenna boresight lies in the XZ plane, while an offset of 90 degrees means that it lies in the YZ plane.

Pointing Type

Description

Targeted

The beam will point to a single object. Click the arrow buttons to move selected objects between the Available Targets and Assigned Targets lists. The beam will point to the object in the Assigned Target list.

Fixed Orientation

The beam will point from a specific orientation. Select an option from the Orientation Method menu. Enter values that define the orientation in the selected method.

Spinning

The radar beam will spin on its axis or sweep in a defined pattern.

Select an option from the Orientation Method menu. Enter values that define the spin axis orientation in the selected method.
The Cone Angle is the angle between the spin axis and the antenna boresight. As the boresight spins about the spin axis, it maintains this angular distance away from the spin axis.
The Spin Rate is the rate at which the boresight spins about the spin axis. The spin is positive in a right-handed sense about the spin axis. You can enter a negative rate to create a spin in the opposite direction.
The Azimuth Offset defines the plane in the parent object's body-fixed frame in which the antenna boresight lies. It is the angle between the X axis and the azimuth vector in the XY plane. An offset of 0 degrees means that the antenna boresight lies in the XZ plane, while an offset of 90 degrees means that it lies in the YZ plane.

Waveforms

From the Beams tab, click the Waveforms subtab. On this tab, you can change the waveform strategy set on the Waveform Strategy Settings tab. Choose from the following adjustment options:

Change Method	Description
Fixed	For the accompanying Waveform parameter, click the ellipsis to select one of the following: If you choose Rectangular, then STK uses the default strategy on the Waveform Strategy Settings tab. If you choose any of the other options, then STK uses only that single waveform, with the range set set on the Waveform Strategy Settings tab.
Range	Select this option if you want to override one or more of the Waveform range defaults set on the Waveform Strategy Settings tab.

Change Method

Description

Fixed

For the accompanying Waveform parameter, click the ellipsis to select one of the following:

If you choose Rectangular, then STK uses the default strategy on the Waveform Strategy Settings tab.
If you choose any of the other options, then STK uses only that single waveform, with the range set set on the Waveform Strategy Settings tab.

Range

Select this option if you want to override one or more of the Waveform range defaults set on the Waveform Strategy Settings tab.

Pointing (radar antenna beams)

Use the Pointing tab to define the pointing type for the entire radar antenna beam system. Each individual beam can have an orientation offset that you define in the Beams tab.

Pointing Type	Description
Targeted	The beam will point to a single object. Click the arrow buttons to move selected objects between the Available Targets and Assigned Targets lists. The beam will point to the object in the Assigned Target list.
Fixed Orientation	The beam will point from a specific orientation. Select an option from the Orientation Method menu. Enter values that define the orientation in the selected method. While the radar remains fixed relative to the parent object, if the parent moves, it will change the orientation of the radar.
Spinning	The radar beam will spin on its axis or sweep in a defined pattern. Select an option from the Orientation Method menu. Enter values that define the spin axis orientation in the selected method. The Cone Angle is the angle between the spin axis and the antenna boresight. As the boresight spins about the spin axis, it maintains this angular distance away from the spin axis. The Spin Rate is the rate at which the boresight spins about the spin axis. The spin is positive in a right-handed sense about the spin axis. You can enter a negative rate to create a spin in the opposite direction. The Azimuth Offset defines the plane in the parent object's body-fixed frame in which the antenna boresight lies. It is the angle between the X axis and the azimuth vector in the XY plane. An offset of 0 degrees means that the antenna boresight lies in the XZ plane, while an offset of 90 degrees means that it lies in the YZ plane.

Pointing Type

Description

Targeted

Fixed Orientation

The beam will point from a specific orientation. Select an option from the Orientation Method menu. Enter values that define the orientation in the selected method. While the radar remains fixed relative to the parent object, if the parent moves, it will change the orientation of the radar.

Spinning

The radar beam will spin on its axis or sweep in a defined pattern.

Select an option from the Orientation Method menu. Enter values that define the spin axis orientation in the selected method.
The Cone Angle is the angle between the spin axis and the antenna boresight. As the boresight spins about the spin axis, it maintains this angular distance away from the spin axis.
The Spin Rate is the rate at which the boresight spins about the spin axis. The spin is positive in a right-handed sense about the spin axis. You can enter a negative rate to create a spin in the opposite direction.
The Azimuth Offset defines the plane in the parent object's body-fixed frame in which the antenna boresight lies. It is the angle between the X axis and the azimuth vector in the XY plane. An offset of 0 degrees means that the antenna boresight lies in the XZ plane, while an offset of 90 degrees means that it lies in the YZ plane.

Location

Use the Location tab to define the radar’s antenna beam system location. The location is defined as a Cartesian offset from the center of the coordinate system of the parent object.

Transmitters

For information on using this tab, refer to the Radar Transmitter Help topic.

Receiver

For information on using this tab, refer to the Radar Receiver Model Help topic.

Jamming

Use the Jamming tab to enable jamming computations. Any monostatic radar can function as a jammer. You can also assign any transmitter as a jammer. Only qualified assets will appear in the Available Jammers list.

Jamming Parameter	Description
Use	Select this check box to incorporate jamming computations. This option enables you to turn the analysis on and off without losing your settings. If you disable jamming, you will save processing time. This can be helpful when you are testing other aspects of a scenario that includes many jammers.
Selection Filter	Use the Selection filter to select entire classes of objects. To select all objects of a class in the scenario, select the check box for that class. The objects will be highlighted in the Available Jammers list. Click the right arrow button to assign all the selected objects as jammers.
Available Jammers/Assigned jammers	Click the arrow buttons to move selected objects between the Available Jammers and Assigned Jammers lists. You can also double-click an object to move it from one list to the other.

Clutter

For directions on specifying clutter, see Radar Clutter.

Detection Processing

Use the Detection Processing tab to define Probability of Detection, Pulse Integration, and Pulse specifications.

Probability of Detection

From the Detection Processing tab, click the Probability of Detection subtab to set the following parameters related to probability of detection.

CFAR Type	Description
Cell Averaging Constant False Alarm Rate (CA-CFAR)	Accounts for the clutter in the range of cells before and after the cell of interest, within the same azimuth radial. Clutter power in the reference cells is averaged to adjust the CFAR threshold. AGI recommends that you use the Clutter Geometry Range of CFAR Cells option with this CFAR type. Clutter will be evaluated in the cells before and after the current cell during computation of CFAR and the probability of detection. For information on parameters that you can set with this option, refer to the Probability of False Alarm and number of CFAR Reference Cells Help topics. “Extending Gandhi's CA-CFAR detection probability formula to pulse integration cases”, Dr. Shen Chiu, DRDC, DoD Canada.
Constant False Alarm Rate	STK will adjust the detection threshold based on the noise in reference 'cells' around the cell of interest. For information on parameters that you can set with this option, refer to the Probability of False Alarm and number of CFAR Reference Cells Help topics.
Non-constant False Alarm Rate	For this option, STK will not adjust the threshold to keep the CFAR constant, and will compute Pdet accordingly. For information on parameters that you can set with this option, refer to the Probability of False Alarm topic.
Ordered Statistics Constant False Alarm Rate (OS-CFAR)	For this option, STK arranges clutter power in the reference cells in descending order, and then subselects to compute CFAR threshold. AGI recommends that you use the Clutter Geometry Range of CFAR Cells option with this CFAR type. Clutter will be evaluated in the cells before and after the current cell during computation of CFAR and the probability of detection. Parts of the CA-CFAR and OS-CFAR algorithm have been enhanced by Dr. Shen Chiu of Defence Research and Development Canada (DRDC). For information on parameters that you can set with this option, refer to the Probability of False Alarm and number of CFAR Reference Cells Help topics. "Extending Gandhi’s OS-CFAR detection probability formula to cases of target-like interference and multiple pulse integration", Dr. Shen Chiu, DRDC, DoD Canada

Probability of Detection Parameter	Description
Probability of False Alarm	This is the probability that a target is declared to be present when in fact none exists. Enter a value in the range 0-1.
Reference Cells	Enter the number of reference cells in an azimuth radial to consider for CFAR computation.

Pulse Integration

From the Detection Processing tab, click the Pulse Integration subtab to select and define the Pulse Integration Mode.

Pulse Integration Parameter	Description
(pulse integration method)	Select one of the following options from the drop-down menu: Goal SNR - This is an integration analysis based on the desired signal-to-noise ratio. Enter an SNR value and the number of Maximum Pulses. Fixed Pulse Number - Enter a Pulse Number value.
Integrator Type	Choose an integrator type: Perfect. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁. Constant Efficiency. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁, where 0.0<<1.0. This option is not available for CW radar. Exponent on Pulse Number. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁, where 0.0<<1.0. This option is not available for CW radar.
Non-Coherent Integration	Select the check box to apply this method, which makes use of a characteristic of noncoherent integration. The integrated gain tends toward SNR_M = M SNR₁, where ranges between 0.0 and 1.0. You can also use an integration gain file. The file specifies the integration gain for a given number of pulses integrated.

Pulse Integration Parameter

Description

(pulse integration method)

Select one of the following options from the drop-down menu:

Goal SNR - This is an integration analysis based on the desired signal-to-noise ratio. Enter an SNR value and the number of Maximum Pulses.
Fixed Pulse Number - Enter a Pulse Number value.

Integrator Type

Choose an integrator type:

Perfect. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁.
Constant Efficiency. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁, where 0.0<<1.0. This option is not available for CW radar.
Exponent on Pulse Number. If M is the number of pulses integrated, SNR₁ is the per-pulse SNR, and SNR_M is the integrated SNR, then SNR_M = M SNR₁, where 0.0<<1.0. This option is not available for CW radar.

Non-Coherent Integration

Select the check box to apply this method, which makes use of a characteristic of noncoherent integration. The integrated gain tends toward SNR_M = M SNR₁, where ranges between 0.0 and 1.0.

You can also use an integration gain file. The file specifies the integration gain for a given number of pulses integrated.

Specs

From the Detection Processing tab, click the Specs subtab to override the STK-computed resolution values with values from the radar spec sheet and also to enable pulse cancellation.

Parameter	Description
Override Computed Resolution values	STK estimates range cell and azimuth resolution from the radar system data: It computes Range Cell Resolution from pulse width. It sets Azimuth Resolution to the antenna 3dB beamwidth. When these resolution values are available as a part of the radar specifications, AGI suggests that you select the check box and override the computed resolution values and enter the values from the radar specification data.
Enable Pulse Cancellation	Select this check box to improve the signal-to-noise ratio (SNR) by enabling pulse cancellation of noise and clutter. The valid range for Number of Pulses is 2 through 5. Pulse type can be either coherent or noncoherent.

Parameter

Description

Override Computed Resolution values

STK estimates range cell and azimuth resolution from the radar system data:

It computes Range Cell Resolution from pulse width.
It sets Azimuth Resolution to the antenna 3dB beamwidth.

When these resolution values are available as a part of the radar specifications, AGI suggests that you select the check box and override the computed resolution values and enter the values from the radar specification data.

Enable Pulse Cancellation

Select this check box to improve the signal-to-noise ratio (SNR) by enabling pulse cancellation of noise and clutter.

The valid range for Number of Pulses is 2 through 5.

Pulse type can be either coherent or noncoherent.

Waveform Strategy Settings

The Multifunction Radar model supports dynamic waveform switching. Rectangular pulse waveform components for short, medium, long, and ultra long ranges are located in the Component Browser. They are based on a ground radar type for short, medium, and long range tracking tasks. To create a custom waveform, click to duplicate, edit, or create a new waveform from a base waveform.

For more information on creating a custom waveform, see Radar Waveform Component.

Multifunction Radar supports dynamic waveform switching for each of the active beams in the multifunction radar system. Select waveform components to set the limits for the short, medium, long, and ultra long range waveforms. A beam will select and use an appropriate waveform based on a target's range from the radar system.

Range limits are set at the radar level and apply to all beams using waveform switching.