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How Are Custom RF Bandpass Filters Made?

Somewhere above you in Earth’s orbit is a satellite transmitting weather maps on 401-402 MHz.

These transmissions are only received due to a highly monitored frequency spectrum. The same is true for other applications that rely on radio frequencies, such as broadcasting towers and military radars. As more and more technology is added to the spectrum, having quality components to filter out the unwanted frequencies, like bandpass filters, is vital!

Source: The complete frequency spectrum, from 9 kHz to 300 GHzSource: The complete frequency spectrum, from 9 kHz to 300 GHz

But because of modern evolved technology, not every application in our world’s crowded frequency spectrum can use an off-the-shelf RF filter. Sometimes, engineers need a special component manufactured to meet their specific requirements. These can be for Electronic Warfare (EW) systems or satellites that intercept messages.

Due to these complex applications that may be operating in high-stress environments, filter customization and performance is paramount. In this article, we cover the meticulous design and development approach that our experienced engineers follow when creating custom RF bandpass filters.

How Custom RF Bandpass Filters are Made: With a Methodical Approach

No single filter technology fits all applications perfectly.

While the holy grail of filters would be capable of meeting all of your project requirements, there are typically many trade-offs to consider. Our team of experienced engineers has been creating custom RF filters for over twenty-five years, and we are ready to help you make those trade-off choices. 

Below, we lay out each step of how custom RF bandpass filters are made so that you can make the best purchasing decision.

Start with the Right Materials

A quality filter starts with quality materials. Whether you need a ceramic bandpass filter or a crystal filter, the material needs to suit your performance requirements.

Source: Q Microwave - Sample Ceramic Bandpass Filter  Source: Q Microwave - Sample Ceramic Bandpass Filter 

A filter manufacturer would ensure that any material they use meets Mil-Standard requirements, as well as high internal quality requirements. One example of this is the ability to screen capacitors down to .1pf tolerance. This allows for consistent and repeatable manufacturing of the most complex bandpass filters. 

To Ensure Excellence, Quality Assurance & Testing

Quality control measures, such as reliability and derating analysis, are critical in RF bandpass filters. As the filter, either using passive or active bandpass filter schematics, is assembled, there are multiple inspection steps throughout the manufacturing process. 

For example, our engineers screen out potential failure points before any components leave our manufacturing floor. This includes: 

  • ESS screening (regardless of customer requirements)
  • Thermal cycling
  • Random vibration testing
  • Burn-in testing
  • Making units fully hermetic through a laser welding process

Your partnered manufacturer would also ideally be backed by certifications, like ISO 9001. 

Once the bandpass filter has been manufactured and tested, it’s ready to be packaged.

Finally, Custom Filter Packaging

Custom filters can come in a wide variety of materials and sizes. Contrary to what you might think, filter packaging does not need to be a standard square box. There are a wide variety of cost-efficient custom packaging shapes and material options, from hermetic to CoPlanar MicroStrip.

A quality manufacturer will help you determine what Surface Mounting packaging best suits your needs:

  1. PWB SMT
  2. Formed Lead
  3. MicroStrip
  4. And/Or CoPlanar MicroStrip
At Q Microwave, our design team works directly with engineers to create custom mechanical outlines for swift integration into your assemblies. Custom filter packaging delivery estimates depend on the size of the component, its shape, material, and other factors. 

However, when you use standard packaging, initial prototype units are typically delivered within 4 to 8 weeks of contract acceptance.

What’s Next?

You might be ready to send over your requirements, but it’s important to do your due diligence when it comes to who is creating your filter.

Choosing a manufacturer is a significant decision that can influence the success of your project. Engineers find a manufacturer who not only meets their technical requirements, but also aligns with their budget and project management needs.

“Creating custom filters is a balancing act that requires meticulous attention to every design and material detail. Navigating the trade-offs between factors like size, cost, and power handling capability is more than an engineering challenge; it's almost an art form that can make or break a system’s performance.”

- David Higginson, Business Development Leader at Q Microwave

Get Your Custom RF Bandpass Filter Project Started!

By working with an experienced RF filter manufacturer, you can count on customization, design precision, and a meticulous process for achieving your desired filter performance.

If you can’t find an off-the-shelf filter that fits your needs, consider Q Microwave. We believe in arming our customers with the knowledge they need to have a timely filter production process – without breaking the bank.

Q Microwave specializes in various custom RF bandpass filter types that provide superior performance:

  • Unique multiplexer designs
  • Custom package options for system integration
  • Rapid semi-custom prototyping
  • Wideband multi-octave filters featuring steep roll-off rejections, low insertion loss, and high-power handling

Are you ready to craft a high-performing, reliable custom RF bandpass filter? Fill out your unique project needs and specifications in the table below, then get in touch with our engineering team!

List Your Unique Specifications! 

Some of our Clients - Raytheon, Northrop Grumman, Bae Systems, Lockheed Martin