A directional coupler selectively diverts part of a signal, whereas a splitter evenly divides the signal among multiple outputs.
Table of Contents
Overview of Power Splitting Devices
Power splitting components and systems are designed to ensure that it is possible to divide power evenly or in a given ratio across two or more paths. These devices are used in a wide range of telecommunications, electronic, and power distribution and management systems. The quality, cost, and efficiency of any splitting device utilized in such a system directly determine the overall effectiveness of the system and its operational costs. Thus, it is important to consider some prominent examples of power splitters and combiners, as well as their qualities and costs. It would be necessary to note that the prices and efficiency rates will be based on the evaluation of the specific case considered here, and both parameters are likely to vary across products.
Definition
One of the examples of a power splitter is a device geared toward ensuring that it is possible to divide the input power across the available outputs. Power splitters are commonly used in many applications because they can help allocate the power without significant losses that cannot be retained. The power combiner, in turn, performs the opposite function, merging several power inputs into a single output. It is significant in various systems where the input power should be combined for performance or efficiency purposes.
List of Prototypes
One of the possible prototypes is a resistive power splitter. These devices use resistors to allocate power among the outputs. These power splitting devices are simple and cost-effective, often in the range of under $50, but they are known to dissipate power as heat, thus affecting efficiency. The efficiency rate typically varies within 50-70%, making the resistive power splitters not the best choice for applications that require low power loss. Reactive power splitters use inductors and capacitors for power division, and these devices are typically more efficient, up to 90%. The cost is typically in the range of $75-$200 as well, but it varies depending on the specifications such as the frequency range and the power handling.
Which type of power splitter is best suited for a particular application depends on several factors, such as the required efficiency of signal splitting and the available budget. Given these factors, it is critically important to understand the differences between the two main power splitters, as well as their advantages and limitations. Hybrid power splitters combine resistive and reactive splitting to achieve the optimal performance and efficiency. Such splitters can boast well over 95% efficiency and handle a wider range of frequencies and power levels than their Wilkinson counterparts. However, the complexity of their design and improved characteristics result in greater costs. Specifically, hybrid power splitters’ prices start at about $200 and only increase as the specifications become more stringent. It is important to mention that these costs are fully justifiable in the case of systems applications where high performance and efficiency are expected. Meanwhile, Wilkinson power splitters owe their name to their inventor, and, unlike their hybrid counterparts, provide equal power division with no loss and no power dissipation. They rely on transmission lines and resistors to achieve such high efficiency, which often reaches 100%. At the same time, the cost of Wilkinson power splitters can vary greatly. At its lowest, the cost is around $100. In applications that require maximum precision and cost-effectiveness, the use of these high-efficiency power splitters is the best solution. Whether being used in telecommunications, power distribution or electronic circuit design, this knowledge will help to maximize system performance and minimize costs.
Understanding Directional Couplers
Directional couplers are necessary elements in the field of RF and microwave engineering which can sample signal energy from a transmission line with no impact on the transmission itself. The principle of their function allows for high precision of signal manipulation, and they are often used in signal routing, measurement, and monitoring systems.
Principle of Operation
The principle of operation of directional couplers is in directional or unidirectional coupling of a certain amount of electromagnetic power from one transmission line to another. This coupled energy can be utilized as the output signal or can be employed for energy addition to the transmission line. As the power is withdrawn, the main signal is unaffected as a transferred energy cannot reflect back to the original line. The coupler, therefore, assures the high precision sampling of power at a well-defined location for further use . Ideally, the coupler should receive 10% of the input power to the coupled port. The directivity of a high-quality coupler must be sufficient , so that the energy from the input to the coupled port is transferred only when the energy is moving in a selected direction.
Construction
Directional couplers use either coupled transmission lines or a waveguide structure to accomplish the directional coupling. The coupling depends on the distance and coupling mechanism between the lines or couplers, and the physical distance determines the efficiency at which power is transferred. Directional couplers also feature an isolation unit that prevents returns of signals or incoming signals to the transmitter. Directional couplers offer some unique advantages:
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Directivity, which enables differentiation between forward-going and reverse waves, both essential for a power-monitoring or feedback control system.
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Isolation is the second most important feature of directional couplers, as it ensures that there are no returns of signals from the input or coming from the output wave of the coupler. In high-quality directional couplers, isolation may exceed 30 dB.
Application
Directional couplers can be used in an extremely broad range of applications and frequencies thanks to their band performance ratings, designed for operation with a specific performance bandwidth, sometimes as broad as several gigahertz. Low directivity sine models are used for simple signal sampling in processes, whereas high directivity units are used for more complex feedback subsystems in such systems as radar and electronic warfare systems.
Comparing Functionality and Applications
Power splitters and power couplers are essential components to telecommunications, signal processing, and electronic circuits design. While these components function in a similar manner and have some overlapping applications, they differ in some crucial aspects. Knowing these differences is critical when selecting one for a specific use, as it will help to ensure optimal performance, efficiency, and costs. Here, we explore the differences in signal distribution and uses in electronic circuits.
Signal Distribution Differences
Power Splitters
Power splitters , as the name implies, are used to distribute power . Technically, they uniformly split an incoming signal into two or multiple output signals, attempting to keep the power levels retained on the outputs exactly as they were on the input. The essential feature of power splitters is that they can divide the power uniformly or based on defined proportions without significant signal losses. For instance, if a 3 dB splitter is used, the power levels on the two outputs would not decrease past simple division, with the input’s power cut in half over the two outputs.
Power Couplers
Power couplers, in contrast to splitters, divert a portion of the power from the primary signal path and transmit it to be used or analyzed by the secondary path . The basic principle behind coupling is that it allows activities to be carried out on the signal via the secondary path without interfering with the primary path. For instance, a typical directional coupler might transmit 10% of the input’s power value to an output referred to as a coupled port, providing a manner for analyzing the main signal in instruments on that path. On the other hand, the output on the direct port will keep traveling without realizing that a portion of it has been diverted, as the directional nature is such that the input is not affected by the direct output.
Applications
The primary use of a power splitter is in systems where single signals need to be distributed between multiple paths. A famous instance is a single antenna that broadcasts signals which need to be transferred between multiple receivers. Similarly, in a simple circuit, the components need to be supplied with equal amounts of power. In networking applications, internet signals must be distributed to different computers through a router. In these applications, equalizing the power is essential .
The primary use of power couplers is in systems that need to sample or monitor the signal or interact with it in some way. For a telecommunications system, for example, the signal’s power levels and quality can be estimated using a power level meter, and thus the couplers can be used to estimate the signal in a simple volt meter. In RF circuits, sampling is done that avoids unbalancing the system. In such an application, the output of the circuit is partially sampled, with the sample then fed into the input in reverse arrows. The directional property allows outward broadcasting work to be done on the outward output without affecting the inward input.
