Contours

The 2D Graphics Contours properties page for an antenna, receiver, transmitter, or radar allows you to define the display of contour lines and antenna patterns.

Option Description
Show Contour Graphics Displays contour graphics in the 2D Graphics window.
Type The contour type: Antenna Gain, EIRP, Flux Density, RIP, or Spectral Flux Density.
Show at Altitude Displays the contour at the specified altitude above the Earth. Otherwise, the contours reflect the value of a property, such as the level of antenna gain at its intersection with the surface of the Earth.
Relative to Maximum If selected, contour level values are assumed to be relative to the maximum value. For example, if the antenna has a maximum EIRP of 30 dBW, a contour value of -5 would plot a 25 dBW contour line.

Level Adding

Use to define the number and type of contour levels to be displayed. Select an Add Method and enter the information appropriate to that method:

Method Procedure
Start, Stop, Step Enter a Start contour value, a Stop value, and a Step value. Use the Add Level button to generate contour values beginning with the Start value and incrementing by the Step specified until the Stop value is reached or exceeded.
Explicit Enter individual contour values. Use the Add Level button to add the new contour value to the list of existing contour values.

Contour graphics are displayed only if the antenna pattern intersects the Earth or the altitude entered in the Altitude field, if the Show at Altitude option is selected. It is possible to have antenna and contour combinations that result in no contour lines actually being drawn. If this occurs, check your contour values, antenna orientation, and vehicle altitude and attitude.

Level Labels

Attribute Description
Show Displays contour level values.
Number of Decimal Digits The number of digits that will be displayed to the right of the decimal point in the contour level values.

Level Attributes

Each contour value has graphics attributes that can be set individually or collectively or, in the case of color, assigned automatically according to a pattern:

Contour level attributes

Attribute Description
Color Method

Defines the color method:

  • Explicit. Enables you to assign colors individually to contour levels.
  • Color Ramp. Applies a spectrum pattern with selected start and end colors.
Start Color/End Color The start and end colors for the spectrum. Applicable only to the Color Ramp method. The Start Color corresponds to the first Level value under Level Attributes.
Line Style Line style for the highlighted contour level. The selected line style displays in both the 2D Graphics and 3D Graphics windows.
Line Width Line width to be used for all contours drawn in the 2D Graphics window.

You can delete a contour level from the list by highlighting it and clicking Remove.

Animation performance may degrade as additional points and lines are drawn to complete the contours.

Separate contour lists are maintained for each contour type so that you can define different values for each type and switch back and forth as desired.

Azimuth and Elevation

Controls the antenna pattern resolution for contouring. The finer the resolution, the smoother the graphics appear. Select one of the following for more information on setting azimuth and elevation values:

Frequency needed to compute gain is set by the antenna's design frequency parameter.

Contour Graphics for Antenna Gain and EIRP

The Gain or EIRP values are computed in the antenna's coordinate system for azimuth and elevation values in the user-defined ranges. In the antenna coordinate system, azimuth is defined as the rotation about the boresight (Z axis), and elevation is defined as the angle off of the boresight.

Parameter Description
Set Azimuth and Elevation Resolution together

Select to set the azimuth and elevation resolution together. Changes made to Azimuth Resolution and Points fields are applied to the Elevation fields.
Resolution
 Enter a value > 0 and <= 30 deg (or the equivalent in another angle unit). This value is the azimuth/elevation angular resolution.
Points
 Define resolution in terms of the number of points in the selected range. The Azimuth or Elevation Resolution field is updated to a calculated value based on dividing the range by the number of points.
Start / Stop Define the range of Azimuth and Elevation values.

Contour Graphics for RIP, Flux Density, and Spectral Flux Density

The RIP, Flux Density, or Spectral Flux Density values are computed in the antenna's coordinate system for 0 to 360 degrees in azimuth and 0 to the specified Max Elevation Angle in elevation. In the antenna coordinate system, azimuth is defined as the rotation about the boresight (Z axis), and elevation is defined as the angle off of the boresight.

Parameter Description
Set Azimuth and Elevation together

Select to set the azimuth and elevation resolution together.
Azimuth Resolution Enter a value > 0 and <= 30 deg (or the equivalent in another angle unit). This value is the azimuth angular resolution.
Elevation Resolution Enter a value > 0 and <= 30 deg (or the equivalent in another angle unit). This value is the elevation angular resolution.
Max Elevation Angle Enter a value >= 0 and <= 90 deg (or the equivalent in another angle unit). The contours will be computed from zero degrees up to this value.

Additional Gains and Losses

The net total of any additional gains and losses on a transmitter will factor into the computation of EIRP, RIP and Spectral Flux Density contours.

The net loss or gain will adjust the transmitted power.

Coordinate System

Select the coordinate system for the antenna pattern resolution for contouring. It can be one of three antenna coordinate systems in STK: polar, rectangular, or spherical Az/El.