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Latest Innovations in Bandpass Frequency & Filters for RF Engineering

We live in an increasingly connected world where having a good signal is the expected norm. For businesses and organizations, this is even more important. Technology has become so entrenched in the modern way of life that daily activities and operations are highly dependent on wireless connections. 

But with so many applications, it’s becoming a noisy and cluttered space. RF engineers are having to be creative in innovating ways to improve filtering capabilities on different bandpass frequencies. 

This is especially true for military and space applications that have to compete against increasing commercial demands for satellite and radio communications. In this article, we look at some of the recent innovations in RF engineering, particularly regarding bandpass frequency and filters.

Gaining an Advantage in Applications that Filter Bandpass Frequencies

Three of the leading requirements for driving innovation are speed, power and size. Engineers need components that deliver communications faster, can be powered for longer, and yet are smaller or more compact.

The challenge is that often these three factors work against each other. Longer-lasting power sources typically are larger rather than smaller. Similarly, smaller bandpass circuits are often limited in their capabilities.

Additional challenges that are a priority for military applications are finding ways to reduce interference and improve security. Let’s look at how these challenges are playing out in military, space and commercial sectors.

Innovations in Military Applications Bandpass Frequency and Filters

One of the areas of focus for military equipment is to increase the capabilities of unmanned vehicles and aircraft. This includes increasing their range of operation, transmission, and payload capability all while ensuring control of the vehicles remains secure. It’s with this in mind that engineers have come up with some innovative solutions.

Intelligent tunable filters:

The idea of being able to tune filters is not new, but more effective ways of doing so are continually being explored. In a military setting, radio interference is a common tactic between adversaries.

Intelligent tuning is a step up from operator tuning, and requires bandpass filter design changes. A recently published study highlights three possible design alternatives:

  1. On-chip tunable bandpass filters provide improved out of band (OOB) rejection with the benefit of the small filter shape allowing for easy integration with RF front end. Continued areas for improvement include greater design flexibility and reducing in-band loss.
  2. Microstrip tunable bandpass filters have greater design flexibility and better performance compared to on-chip TBPFs. Their integration capabilities and lower costs combine to make them a preferred choice.
  3. Substrate integrated waveguide bandpass filters use twin stubs that are loaded independently to achieve frequency tuning. A primary benefit is that changes in one frequency have little impact on the second stub.

Operating in close quarters and with multiple sources leveraging similar frequencies, it’s vital to be effective in identifying and blocking adversary attempts to jam signals or listen in on communications. Intelligently tunable filters seek to address this by analyzing which frequencies are already in use and then seeking out an alternate secure frequency to switch to. 

Creating more compact, affordable bandpass filters with 3D printing

The applications for bandpass frequency filters require them to be both robust and compact. The U.S. military is now looking to learn from commercial RF applications, specifically cell phone technologies. Cell phones have been designed to be both portable and compact. While few models are built to withstand extreme military conditions, their use of 5G communication networks provides insights on how to leverage bandpass frequencies for different applications.

In this, bandpass filters will play a critical role with the requirement that they can be produced at a low cost and be able to handle extreme environmental conditions. 3D printing is one of the proposed solutions.

Historically, vulnerabilities occur when components are joined to make up the filters because multiple materials are used. Also the micro accuracy required when making RF filters is hard to achieve when the requirement is to make them even more compact. New techniques using stereolithic (SLA) 3D printing have been showing promising results to produce high-quality, low-cost bandpass filters.

Bandpass Frequency Filters in Space Innovation

With the majority of communications on Earth taking place via satellite-linked technologies, researchers are continually looking to improve signal filtering. For astronomers, it’s not just data signals that matter, imaging is as important. Developing the technology to be able to improve on space imagery sent back to Earth has required improvements in filters. 

One of the most exciting space projects in recent years is the Euclid mission which aims to get a better understanding of the origins of the universe. The parameters for this project require a high degree of accuracy while attempting to gather data from a vast spectrum. To put it in perspective, part of the project objectives read as follows: “Euclid must determine the near-infrared (NIR) photometry of at least 1 billion galaxies to a relative accuracy of better than 1.5%.”

Data gathering will be across three primary pass bands which are twice the width of conventional pass bands and will not be impacted by atmospheric absorption. RF filters will play a vital role in refining out-of-band blocking to improve the integrity of the data to be analyzed.

The Future of Bandpass Frequency Filtering

Improving clarity and accuracy of communication is not only a priority for military and space research. Commercial applications require this too. This is especially true as stakeholders begin to collaborate and utilize the same satellite resources for their own purposes. Because of this, the applications of bandpass frequency filtering are likely to broaden, becoming even more complex.

In this crowded world of bandpass frequencies, Q Microwave is a leader in RF solutions. For more than 25 years we have provided military and space specialists with off-the-shelf and customized RF filters and subsystem components. We draw on technical expertise and work to gain a deep understanding of customer requirements with every customized request.

Read more about our RF engineering services and find out why we are a trusted partner when it comes to innovating bandpass frequency and RF solutions for customers across the globe.