12/1/2022 0 Comments Parallel planesThe first case from Figure 1 with ideally equipotential planes is just a model – 2 ports from the trace to the planes are used to excite only a TEM wave. TDR plot of a trace with two equal-potential reference planes (red plot) and a TDR plot of a trace with reference to just one plane at the excitation location (blue plot). In this simple case, the impedance of the trace referencing just one plane will be about 1 Ohm off on a time domain reflectometry (TDR) plot, as shown in Figure 3.įigure 3. In addition, the signal transformation changes the observable trace impedance. Unfortunately, those effects are practically unpredictable for complex designs. Waves in PPW are unwanted noise that can cause electromagnetic compatibility or interference (EMC/EMI) problems as well as unwanted propagation of signals between the components through parallel planes (multi-path propagation). Referencing the excitation to just one of the planes (GND) causes the signal to transform into a useful TEM wave as well as into radial waves of PPW. Both ports are via-ports with signal terminal at the trace and reference terminals at the bottom plane only. The trace segment is excited with a 1 V, 50 Ohm, 20 GHz harmonic source at the bottom left port. Power flow density in a trace as referenced to one plane. Figure 2 illustrates what happens with the signal in this case (click on graphic to see animation).įigure 2. What happens if one of the planes is a power plane and the other is a ground plane? Then the equipotentiality cannot be enforced. Related ResourcesĢ24 Gb/s Per Lane: Options and Challenges Both ports are via-ports with signal terminal at the trace and reference terminals simultaneously at the top and bottom planes. Power flow density in a trace with equipotential planes. For instance, if we launch a TEM wave into a trace with ideal equipotentiality of the parallel planes, we can observe the wave propagating strictly along the traces as in Figure 1 (click on graphic to see animation).įigure 1. Both waves are useful, but they have to be separated. TEM waves are used to transmit the signal between components while PPW waves are used to deliver power to the components. What can be simpler than that? Well, the fact that it is a three-conductor structure that supports propagation of transverse electromagnetic (TEM) waves as well as waves of the parallel plate waveguide (PPW) –superposition of radial or plane waves-complicates things. This means that $a$ must be $6$ for the two planes to be parallel.Traces on PCBs are often routed between parallel planes. To find one pair, we can start with Plane $\boldsymbol$ The rectangular prism shown above contains multiple pairs of parallel planes. Look for a reference plane and find a second plane that is facing opposite it. To identify parallel planes, we have to ensure that the planes we’re comparing are lying along with the same space. We’ve now learned about parallel planes, so it’s time for us to practice looking for parallel planes in three-dimensional figures. Two bookshelves facing each other are another great example of parallel planes.Each step extends along the same direction as one another, but these steps will never intersect each other. The steps on our stairs are also examples of parallel planes.They extend along with the same space (our home), but these two planes will never meet. Our homes’ ceilings and floors are great examples of parallel planes.What are some real-world examples of parallel planes? Planes that are not parallel and intersect along a line are called intersecting planes. What do we call planes that intersect? Yes, you guessed it right. Observe how the two extends in the same direction, but these planes will never meet. The figure above shows an example of two parallel planes. verify whether two planes (from equations) are parallelĪs mentioned in the first section, when two planes lie in the same direction but do not meet, we call them parallel planes.In the next sections, we’ll learn how to: These concepts were extended to parallel planes. Need some refresher? You can check out the following links: Parallel planes are planes that never intersect. Let’s start with recalling what parallel planes are: Want to know more about parallel planes? This article is a great source of information about parallel planes, their properties, and their application.
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