1. 来自STK官网的解释
主要信息来源：https://help.agi.com/stk/
STK在线帮助版本：12.0
Google在线翻译，有补充。
1.1 Sensor（传感器）
Sensor performance is a major concern for satellite system engineers and integrators. Sensors can be used to represent such equipment as optical or radar sensors, receiving or transmitting antennas, and lasers. The sensor object can also be useful for defining another object's field of view. Sensors are children of vehicles, facilities and targets. The sensor object can also have children of its own.
传感器性能是卫星系统工程师和集成商关注的主要问题。传感器可用于表示光学或雷达传感器、接收或发射天线和激光器等设备。传感器对象也可用于定义针对另一个对象的视野。传感器是车辆、设施和目标对象的子节点（传感器本身不能作为场景的子节点）。传感器对象也可以有自己的子节点，传感器的可能子节点包括：雷达、接收机、发射机、天线。
1.1.1 传感器基本属性
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| Set parameters defining a sensor's field of view. 设置定义传感器视场的参数。包括七类传感器：
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| Position a sensor with respect to its parent object. 设置传感器相对于父对象的位置，有5种模式：
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| Set parameters to determine how a sensor is aimed, e.g. with respect to its parent object, the central body, objects selected for tracking, etc. 设置参数以确定传感器相对于其父对象、中心体、指定跟踪的目标等的指向/瞄准方式，包括：
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| Define an azimuth-elevation mask for the sensor. 为传感器定义方位仰角掩码。 |
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| Select a refraction model to constrain an atmosphere-based sensor's line of sight and elevation angles. 选择折射模型来约束基于大气的传感器的视线和仰角（大气折射）。 |
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| Define the resolution of the sensor in terms of focus and image quality. 根据焦点和图像质量定义传感器的分辨率。 |
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| Record useful information about the sensor. |
1.1.2 传感器约束（Constraints）属性
| Property |
Description |
| Impose minimum elevation and line-of-sight constraints on access from the sensor to another object. 对从传感器到另一个物体的访问施加最小仰角和视线限制。 |
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| Impose a variety of access constraints from the sensor to another object based on the position of the Sun and the Moon. 根据太阳和月亮的位置，对从传感器到另一个物体的各种访问限制。 |
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| Impose time-based access constraints from the sensor to another object. 从传感器到另一个物体施加基于时间的访问限制。 |
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| impose a variety of sensor-specific constraints. 施加各种传感器特定的约束。 |
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| Use inclusion and exclusion zones to define areas where access is or is not allowed. 使用包含区和排除区来定义允许或不允许访问的区域。 |
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| Limit access based on sensor characteristics and the quality of the inview. 根据传感器特性和考虑中的（inview）质量限制访问。 |
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| Define the relationship between the sensor and the target of that sensor. 定义传感器与该传感器的目标之间的关系。 |
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| Constrain access computations with respect to any valid vector or angle. 约束关于任何有效向量或角度的访问计算。 |
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| Special access constraints are defined in terms of geostationary belt exclusion, height above horizon, terrain grazing angle and exclusion of other scenario objects. 根据地球静止带排除、地平线以上高度、地形放牧角度和排除其他场景对象定义的特殊访问限制。 |
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| An interface is provided for defining custom constraints in terms of user-supplied scripts created in Perl, VBScript and MATLAB. 根据在Perl、VBScript和MATLAB中创建的用户提供的脚本提供一个用户自定义约束的接口。 |
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| Set a signal-to-noise ratio (SNR) on an EOIR sensor. 设置EOIR传感器的信噪比（SNR）。 |
1.2 Radar（雷达）
The Radar object models the characteristics of a radar system and its environment.
雷达对象对雷达系统及其环境的特征进行建模。雷达对象的父节点可能是：卫星、飞机、舰船、车辆工具（GroundVehicle）、运载工具、导弹、地面站、目标、传感器等。雷达对象没有（也不能有）子节点。
雷达是传感器的一种，是对传感器的进一步建模。
雷达分析模块是STK中的一个（相对独立的）专业分析工具，它提供了专业的雷达系统的建模分析和图形显示功能，可以设计多种任务中的雷达应用，而且能够为对象的RCS特征建模，计算可见性以及生成雷达的报告和图表等。
1.2.1 雷达基本属性
| Property |
Description |
| Define the characteristics of the radar. 定义雷达的特性。在雷达基本属性中，包括：
各参数设置本文不再展开，可以看出雷达就是一类特殊的传感器，而且有许多不同种类的雷达。 |
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| Model atmospheric refraction. 对大气折射模型建模。 |
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| Record useful information about the antenna. |
1.2.2 雷达约束属性
| Property |
Description |
| Radar Search/Track Constraints property pages allow minimum and maximum values to be entered for several parameters and presents a variety of doppler options: 雷达搜索/跟踪约束属性页面允许为多个参数输入最小值和最大值，并提供各种多普勒选项：
The STK Radar SAR computation and constraints can be extended with the Search/Track plug-in constraint. See Search/Track User Plugin. |
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| SAR property pages allow for the imposition of a variety of constraints on synthetic aperture (SAR) radar.
The STK Radar SAR computation and constraints can be extended with the Search/Track plug-in constraint. See SAR User Plugin. |
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| Enforce access constraints between the transmitter and receiver and set minimum and maximum values for the bistatic angle. While other access constraints are always enforced between the bistatic transmitter and the target/receiver, radar-specific constraints defined for a bistatic transmitter do not constrain access for the radar using it. 在发射器和接收器之间实施访问限制，并设置双站角度的最小值和最大值。 虽然在双基地发射器和目标/接收器之间总是强制执行其他访问约束，但为双基地发射器定义的雷达特定约束不会限制使用它的雷达的访问。 |
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| Impose minimum elevation and line-of-sight constraints on access from the radar to another object. 对从雷达到另一个物体的访问施加最小仰角和视线限制。 |
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| Impose constraints on a radar related to system noise temperature. 对雷达施加与系统噪声温度相关的约束。 |
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1.2.3 雷达RF属性
| Property |
Description |
| Apply environmental factors that affect the performance of a communications link or a radar system. 应用影响通信链路或雷达系统性能的环境因素。 |
1.3 Transmitter（发射机）
The Transmitter object models the characteristics of the transmitter, the antenna it uses and the environment in which it operates.
发射机对象对发射机的特性、它使用的天线以及它运行的环境进行建模。发射机对象的父节点可能是（参见雷达对象的父节点）。发射机对象没有（也不能有）子节点。
1.3.1 发射机基本属性
| Property |
Description |
| Define the characteristics of the transmitter. 定义发射机特性。STK提供9类（内置）发射机，其中有3类为re-transmitter，各类发射机的基本特性包括：规格型号（频率/功率/增益）、调制器、滤波器、附加增益和损耗等。 Transmitter Models
Basic Re-Transmitter Models
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| Model atmospheric refraction. |
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| Record useful information about the antenna. |
1.3.2 发射机约束属性
| Property |
Description |
| Impose minimum elevation and line-of-sight constraints on access from the transmitter to another object. 对从发射器到另一个物体的访问施加最小仰角和视线限制。 |
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| Impose constraints on a transmitter related to system noise temperature. 对发射机施加与系统噪声温度相关的约束。 |
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| Impose a variety of communications link constraints on the transmitter. 对发射机施加各种通信链路约束。 |
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| Set constraints in terms of certain link performance indicators as affected by interference. 根据受干扰影响的某些链路性能指标设置约束。 |
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1.3.3 发射机RF属性
| Property |
Description |
| Apply environmental factors that affect the performance of a communications link or a radar system. 应用影响通信链路或雷达系统性能的环境因素。 |
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| Specify the radar cross section (RCS) parameters. 指定雷达横截面 (RCS) 参数。 |
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| Specify a Clutter Coefficient for the Clutter Map or load the Radar Advanced Environment (RAE) Database. 为杂波图指定杂波系数或加载雷达高级环境 (RAE) 数据库。 |
1.3.4 发射机Laser属性
| Property |
Description |
| Apply environmental factors that affect the performance of a laser communications link. 应用影响激光通信链路性能的环境因素。 |
1.4 Receiver（接收机）
The Receiver object models the characteristics of a receiver, the antenna it uses and the environment in which it operates.
接收机对象对接收器的特性、它使用的天线以及它运行的环境进行建模。接收机对象的父节点可能是（参见雷达对象的父节点）。接收机对象没有（也不能有）子节点。
1.4.1 接收机基本属性
| Property |
Description |
| Define the characteristics of the receiver. 定义接收机特性。STK提供8类（内置）接收机，各类接收机的基本特性包括：规格型号（频率/功率/增益）、滤波器、附加增益和损耗。（相比发射机少了调制器）。
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| Model atmospheric refraction. |
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| Record useful information about the receiver. |
1.4.2 接收机约束属性
| Property |
Description |
| Impose minimum elevation and line-of-sight constraints on access from the receiver to another object. 对从接收器到另一个对象的访问施加最小仰角和视线限制。 |
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| Impose constraints on a receiver related to system noise temperature. 对接收机施加与系统噪声温度相关的约束 |
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| Impose a variety of communications link constraints on the receiver. 对接收机施加各种通信链路约束。 |
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| Set constraints in terms of certain link performance indicators as affected by interference. 根据受干扰影响的某些链路性能指标设置约束。 |
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1.4.3 接收机RF属性
参见发射机对象。
1.4.4 接收机Rader属性
参见发射机对象。
1.5 Antenna（天线）
The Antenna object models the properties and behavior of an antenna.
天线对象对天线的属性和行为进行建模。天线对象的父节点可能是（参见雷达对象的父节点）。天线机对象没有（也不能有）子节点。
经实测，STK9.2.2中，天线不能直接作为雷达、发射机、接收机的子节点。
1.5.1 天线基本属性
| Property |
Description |
| Define the characteristics of the antenna. STK9.2.2有45种内置的天线。 |
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| Specify the orientation of the antenna coordinate frame relative to the coordinate frame of the parent object. |
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| Model atmospheric refraction. |
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| Record useful information about the antenna. |
1.5.2 天线约束属性
| Property |
Description |
| Impose minimum elevation and line-of-sight constraints on access from the antenna to another object. 对从天线到另一个物体的访问施加最小仰角和视线限制。 |
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1.5.3 天线RF属性
参见发射机对象。
1.5.4 天线Rader属性
参见发射机对象。
2. STK关于“Linking to an Antenna that Resides on a Sensor”的解释
https://help.agi.com/stk/11.7.1/index.htm#comm/CommRadar03.htm#sensor
To model actual, real-world configurations as closely as possible, STK anticipates that the antenna object will be placed on the sensor, so it can inherit sensor properties such as location and pointing. Conversely, radar, receiver, or transmitter objects that link to this antenna must be on the sensor's parent object, not on the sensor itself. It is helpful in this context, to think of the sensor as the gimbal for the antenna. Yet, the radar, receiver, or transmitter represents the electronic components that do not need pointing and whose location does not affect RF properties. While STK allows a radar, receiver, or transmitter object to be placed directly on a sensor, the use of embedded antennas is the only available option in this case.
为了尽可能模拟真实世界的配置，STK预期天线对象将放置在传感器上，因此它可以继承传感器属性，例如位置和指向。相反，链接到此天线的雷达、接收器或发射器对象必须位于传感器的父对象上，而不是传感器本身。 在这种情况下，将传感器视为天线的万向节是很有帮助的。 然而，雷达、接收器或发射器代表了不需要指向并且其位置不会影响射频特性的电子元件。 虽然STK允许将雷达、接收器或发射器物体直接放置在传感器上，但在这种情况下，使用嵌入式天线是唯一可用的选项。
3. 个人理解
注：纯属个人理解，非专业！
- 四者共性：都必须有父节点，不能单独作为场景中的对象。四者为STK中建立通信系统（CommSystem）的基本对象。
- 传感器可以作为父节点，其子节点可以是雷达、发射机、接收机、天线。
- 传感器：概念更宽泛，例如温度传感器、压力传感器等，STK中的传感器为通信传感器，STK中传感器主要用于一个对象针对另一个对象的视野（field of view）。
- 雷达是传感器的一个大类，传感器有一种类型为SAR，就是雷达的一种，具体类型的雷达参数更为具体，雷达除了传感，通常还需要识别（探测），例如雷达搜索/跟踪的参数‘探测概率’。
- 发射机/接收机比雷达更为进一步，为信号的发射和接收进一步指定参数。
- 天线作为无线电波与发射/接收模块之间的接口，通常与发射机和接收机一同使用。