Antenna
Define satellite and ground station antennas — pattern types, mounting, pointing modes, and design frequency — for use in link budget computations.
An antenna defines the radiation pattern and mounting of a communication antenna on your satellite or ground station. Antennas are used in link budget computations to compute gain at each timestep based on the off-boresight angle to the line of sight.
Satellite antennas
Adding a satellite antenna
- In the Scenario tab, find the satellite in the satellite list.
- Open the satellite’s more options menu (
...). - Select Add New Antenna.
This opens the Antenna Settings modal, which includes a live 2D polar pattern plot. To edit an existing antenna, expand the satellite in the list and click the antenna’s name.
Satellite antenna settings
| Field | Description | Range / Options |
|---|---|---|
| Name | Free text | Defaults to “New Antenna” (auto-numbered) |
| Color | Display color in 3D views | Color picker |
| Body Face | Which bus face the antenna is mounted on | X+, X-, Y+, Y-, Z+, Z- (labeled Nadir, Zenith, Ram, Anti-Ram, Right, Left) |
| Yaw | Rotation around body Z | -180° to 180° |
| Pitch | Rotation around body Y | -90° to 90° |
| Roll | Rotation around body X | -180° to 180° |
| Pattern Type | Radiation pattern model | See table below |
| Pattern Parameters | Type-specific gain parameters | Depends on pattern type |
| Design Frequency | The frequency the antenna is tuned to | In GHz or MHz |
| Pointing Mode | How the antenna is oriented | fixed or access-track |
Rotations use the same extrinsic Yaw → Pitch → Roll convention as sensors.
Default values
| Field | Default |
|---|---|
| Body Face | Z- |
| Pattern Type | Parabolic Dish |
| Diameter | 0.3 m |
| Efficiency | 0.65 |
| Design Frequency | 2.2 GHz |
| Pointing Mode | fixed |
| Color | #0066ff |
Pointing modes (satellite)
| Mode | Description |
|---|---|
| Fixed | The antenna maintains a fixed orientation relative to the satellite body. Gain varies as the satellite attitude changes relative to the ground station. |
| Access-track | The antenna steers to track the ground station during access windows, keeping the boresight aligned with the line of sight. |
Ground station antennas
Ground station antennas are defined in the ground station settings. They have no body-face mounting (a ground station has no bus) — instead, they use azimuth/elevation pointing.
Ground station antenna settings
| Field | Description | Range / Options |
|---|---|---|
| Name | Free text | — |
| Pattern Type | Radiation pattern model | See table below |
| Pattern Parameters | Type-specific gain parameters | Depends on pattern type |
| Design Frequency | The frequency the antenna is tuned to | In GHz or MHz |
| Pointing Mode | How the antenna is oriented | auto-track, fixed, or zenith |
| Fixed Azimuth | For fixed mode | 0–360° |
| Fixed Elevation | For fixed mode | 0–90° |
Pointing modes (ground station)
| Mode | Description |
|---|---|
| Auto-track | The antenna tracks the satellite during passes, keeping the boresight pointed at it. |
| Fixed | The antenna points at a fixed azimuth and elevation. Gain varies as the satellite moves through the sky. |
| Zenith | The antenna points straight up (90° elevation). Only sees satellites passing directly overhead. |
Antenna pattern types
| Pattern | Model | Key Parameters | Gain computed at |
|---|---|---|---|
| Isotropic | 0 dBi everywhere | — | — |
| Dipole (half-wave) | G(θ) = 1.64 · [cos(π/2 · cos θ) / sin θ]² | Peak 2.15 dBi broadside | Design frequency |
| Monopole (quarter-wave) | G(θ) = 3.28 · sin²θ | Peak 5.16 dBi broadside | Design frequency |
| Parabolic Dish | Airy pattern: G(θ) = η · (πD/λ)² · [2J₁(u)/u]² | Diameter, efficiency | Link frequency |
| Horn | sinc² aperture approximation | Peak gain, HPBW | Link frequency |
| Patch | G(θ) = G₀ − 12·(θ/HPBW)² within HPBW | Peak gain, HPBW | Design frequency |
| Custom | Same parabolic approximation as patch | Peak gain, HPBW | Design frequency |
Broadband antennas (parabolic, horn, isotropic) compute gain at the link frequency — the design frequency is used only for the 2D polar pattern visualization.
Tuned antennas (dipole, monopole, patch) compute gain at the design frequency — the actual frequency the antenna is tuned to.
Visualizing antennas
- Model tab — the 3D CubeSat viewer renders each visible antenna’s radiation pattern as a translucent surface mesh, oriented along the boresight direction. Use the show/hide toggle in the Model sidebar.
- Antenna Settings modal — includes a live 2D polar plot of the gain pattern that updates as you change parameters.
Using antennas in link budget
Antennas are referenced in the link budget configuration:
- For a downlink (Sat → GS), the TX antenna is selected from the satellite’s antennas and the RX antenna from the ground station’s antennas.
- For an uplink (GS → Sat), the TX antenna is from the ground station and the RX antenna from the satellite.
At each timestep within an access window, the TX and RX antenna gains are computed from the off-boresight angle between the antenna boresight and the line-of-sight vector. See Link Budget for the full equations.
A link budget requires at least one antenna on the satellite and one on the ground station. If either is missing, the computation will not run — configure antennas in the Scenario tab first.
Wire antennas on ground stations
Dipole and monopole antennas are physically fixed rods. When selected for a ground station, the pointing mode is automatically set to fixed and the azimuth/elevation fields describe the rod orientation (defaulting to vertical, 90° elevation). Wire antennas cannot auto-track.
Limitations
- The satellite must be propagated before its antennas appear in the link budget selector.
- Hidden antennas are excluded from link budget selection.
- Antenna rotations are limited to: yaw/roll ±180°, pitch ±90°.
- Editing an antenna triggers recomputation of any existing link budgets that use it.
- All radiation patterns are rotationally symmetric around the boresight axis — azimuth and elevation cuts are identical.
- Auto-track and access-track are ideal — the boresight is assumed perfectly aligned with the line of sight. No pointing error or slew loss is modeled.
- Pointing loss and atmospheric loss are currently set to 0 dB, so computed margins are best-case.
Next steps
- Link Budget — antenna gain models and link margin computation
- Ground Stations — ground station antenna configuration
- Model — visualize antenna radiation patterns on the 3D satellite model
- Target Pointing — attitude overrides affect antenna boresight alignment