Innovating essential high technology systems with demanding specifications is always challenging; making any sort of difference requires extensive resources and deep subject matter knowledge.

But that’s what keeps it interesting.

To help customers with filter selection, we generally provide a lot of information on what our filters can do. But in this new Filter Basics Series, we are taking a step back to cover some background information on how filters do what they do. Regardless of the technology behind the filter, there are several key concepts that all filters share that we will dive into throughout this series. By providing this detailed fundamental filter information, we hope to help you simplify your future filtering decisions. 

In part 8 of this series, we dive deeper into bandwidth by looking at the history of bandwidth, how bandwidth dictates data rate, and why the type of filter required will vary depending on an application’s bandwidth requirements.

When selecting a filter implementation, one factor that is common across all frequencies is optimizing the size of the filter given the application and the required performance. At mmWave frequencies this can be prove to be a particularly interesting problem, given the change in the physical dimensions of the system as one moves from say 600MHz to 38GHz. 

To help customers with filter selection, we generally provide a lot of information on what our filters can do. But in this new Filter Basics Series, we are taking a step back to cover some background information on how filters do what they do. Regardless of the technology behind the filter, there are several key concepts that all filters share that we will dive into throughout this series. By providing this detailed fundamental filter information, we hope to help you simplify your future filtering decisions.

In part 4 of this series, we provide overviews of the main filter types and key filter technologies available today.

RF circuits for applications in the mmWave range (30 to 300 GHz) require high-performance filtering to meet the high-data, high-speed functionality that operating at these higher frequencies promises. However, filters for devices operating in the mmWave range will not function optimally if your printed circuit board (PCB) is not configured appropriately. For this reason, RF design engineers need to make a number of critical PCB design decisions that range from selecting the right materials to developing a board configuration that will limit common issues such as spurious-wave-mode propagation, conductor and radiation losses, unwanted resonance, and dispersion.

Spectral efficiency, or bandwidth efficiency, tells us about the channel capacity over a 1Hz bandwidth. It is a measure of the efficiency of a physical layer protocol when it comes to utilizing the spectrum available. To understand how spectral efficiency is calculated, it’s first important to understand the Shannon-Hartley Theorem in the context of 5G mmWave applications (which we discussed in an earlier blog post).

To help customers with filter selection, we generally provide a lot of information on what our filters can do. But in this new Filter Basics Series, we are taking a step back to cover some background information on how filters do what they do. Regardless of the technology behind the filter, there are several key concepts that all filters share that we will dive into throughout this series. By providing this detailed fundamental filter information, we hope to help you simplify your future filtering decisions. 

In part 3 of this series, we aim to help simplify filter selection by providing an overview and reference point for five of the most commonly discussed filter technology specifications.

At this point, you’ve likely seen a slew of mainstream news articles about 5G causing safety concerns around air travel. In fact, ahead of the rollout of new 5G services from major US telecom companies including Verizon and AT&T on Jan. 19, 2022, many international airlines canceled or delayed flights to major US airports where they believed 5G signals could possibly interfere with the radar signals required to properly operate landing equipment on their planes.

At Knowles Precision Devices, we truly do love all things RF. While we are focused on using our expertise in ceramics and thin film manufacturing to innovate on our high-performance filters, our engineers also enjoy keeping up with the trends impacting the entire RF “ecosystem.” This includes dedicating time to experimenting with various open-source RF modeling and analysis tools that we think our potential non-design engineer customers might find useful. One open-source RF and microwave network analysis tool we have been playing around with lately that we feel does a particularly good job is scikit-rf, which is based on the Python programming language.

The advent of fifth generation (5G) communications brings an increased interest in Millimeter Wave (mmWave) technologies. One of the biggest technology challenges engineers face with 5G is how to implement sufficiently high-performance RF filtering in mmWave applications. Given the frequencies involved a distributed element planar approach, such as using Microstrip or Stripline, is often ideal for constructing resonators and filters.