The Process of Turning a Bandpass Filter Schematic Into an RF Filter

When an off-the-shelf filter doesn’t cut it for your project, the only solution is to get a custom RF filter from a trusted source. But when the success of your team hinges on an unknown manufacturing process, it can make your life more stressful.

That’s why we’re here to explain our process. With over 25 years of experience in RF engineering, Q Microwave has designed and implemented a range of RF filters. From the initial concept through to deployment, our engineers ensure high performance and reliability for our RF components. This dedication is crucial to maintaining our high standards, especially with the RF filter market size expected to grow to $308.4 million by 2028.

But what exactly happens during our methodical process of converting a custom bandpass filter schematic into a functional RF filter? To answer this question, we will walk you through each step of our manufacturing process below.

Let’s start by explaining what happens directly after you send us your specific application needs and bandpass filter requirements.

Step 1: Initial Design Phase

Once we receive your notes, we determine the best design method and filter material, such as ceramic, lumped element, or combline. We promise a fast turnaround time on this analysis to get the project moving. The actual generation of initial design files on our side generally takes three to five working days.

Not sure what to send our team? Fill out this PDF with your requirements and email it to us!

Once we have an initial bandpass filter schematic design, we create a simulated design of what the final product will look like. Then we send you an S2P file – which allows you to review the expected performance of the filter in your own model.

This transparency allows you and our team to discuss if this final RF filter design works for you, or if we need to adjust anything.

• If it doesn’t quite work for your project, we collaborate closely with you to create a new simulation file that meets your needs precisely. 
• If it does work, we move on to your project limits.

Now we ask, “What are your other restrictions?”

At this point, we determine if there are other requirements beyond just electrical performance that are needed. This could mean your microwave filter might need environmental screening or any limitations on package sizing.

Note: As this initial design is created, if you’re constrained in size, then it might change the filter material and performance we can provide.

Sample mechanical drawing from the Q Microwave engineering team.

Now that we know these three items, we can create a realistic quote for your review:

1. How much time the filter will take to create
2. What type of material we'll be using 
3. How much additional testing is required

Step 2: Agree on a Preliminary Quote

This quote will be a valid proposal with pricing, specs, and more information for the entire process. At Q Microwave, we are fully transparent with our pricing. This intensive initial design phase is to prevent any unknown cost increases down the line.

All of the initial design ideas, mechanical outlines, and recommendations come before anything is signed. This is to ensure that we only have your best interest in mind and that our project stays within its scope with respect to your budget and timeline.

Note: This process is only for RF filters, not microwave subcomponents.

Step 3: Production Begins 

Once our quote is approved, we begin with a kick-off call to introduce your primary contact. This contact streamlines communications on both ends so that you know who to call for questions or concerns.

At this point, the filter production starts. Our engineers will comb through your design requirements for both the electrical and mechanical parts. We generate an initial traveler (which outlines every manufacturing step needed) and the bill of materials. The engineer then purchases any materials that are needed. This is where lead times can be extended, depending on our material vendor’s timelines and how much of the material we have on-site.

Any custom design will generally take four to six weeks depending on the design’s complexity. If it is a hermetically sealed assembly, it may require additional machining steps. This could extend the timeline by another two weeks.

Sample Ceramic Bandpass Filter from Q Microwave

While our purchasing team waits for materials (if this step is needed), our engineers generate initial documentation for how your RF filter will be assembled, initial documentation for testing, and what steps need to be done during the testing process. 

Once the material arrives, we put everything into a kit. This kit goes to our engineering assembly line and they use the bandpass filter schematic documentation to put it together. 

Then, they perform an initial assembly test to make sure it performs well. Then it'll go back to assembly for cleaning and any sort of cleanup, then it'll go to engineering for a final frequency tuning, or final alignment, of the filter. Then it'll go through additional environmental requirements as needed. 

Once again, our team will go through any additional mechanical and environmental requirements after it's covered. The filter will then go to a marking and label room followed by final testing procedures to make sure it meets all of your requirements and that the bandpass filter transfer function works.

After assembly and cleaning, the component will go through inspection. After the final test, it'll go back to inspection again to ensure that all the paperwork and procedures were followed properly.

We admit that our process features a lot of testing and re-testing – but there’s a reason why our RF engineering team is called “kickass!” We don’t cut corners.

Once the product has been thoroughly analyzed, we ship it out to you!

Step 4: Billing

Our team does not bill you until the final bandpass filter is shipped. We normally do not see any drastic change in pricing after the initial quote because we take the time to do our due diligence at the very beginning of our partnership.

The final bill will also include any NRA or non-recurring engineering charges. Depending on the complexity and needed customization, there will likely be an NRA fee. We often get questions about what this NRA fee is for, since we have already done all of the designs and documentation. 

But this documentation, which includes the mechanical outline, filter performance, etc., will be referenced the next time you need the same filter. At that point, we would not charge you any additional fees because this documentation is already created.

We Check In With Your Satisfaction

After we ship the final RF filter, it’s normal for our customers to send us feedback and ratings from your entire business unit. These ratings are based on delivery time and quality of our microwave filters. 

Our team is always improving our process and we welcome any feedback our customers have for us. We do our best to mitigate any delays in a project by having multiple vendors that can supply us with similar products, so any unforeseen gap in materials can be covered by a different supplier if needed. 

However, if there is a major change in the specification of material or prototype design, only then would the pricing and production timeline be impacted. Our engineering team will always be upfront with you about these changes and what your options are.

The Journey From a Bandpass Filter Schematic to a Custom RF Filter is Now Complete!

Our process for creating a high-performance and resilient microwave filter from a bandpass filter schematic is a very detailed one, but worth it.

From the initial design phase to the final shipping, each step is guided by over 25 years of RF engineering expertise, ensuring that every custom filter meets the highest standards of performance and reliability.

The creation of a custom RF filter is more than just a technical endeavor – it is a partnership built on trust, innovation, and a relentless pursuit of quality.

That’s why our process is a testament to the unwavering commitment to excellence that defines Q Microwave. If you want to get your custom filter designed, learn more about our RF filter offerings today.