Standard off-the-shelf components are designed to perform reliably within well-defined operating envelopes. If you have enough physical space in your system or device, cavity filters are a good choice because they offer strong selectivity and can handle higher power levels reliably. If the application involves lower power and space is limited, lumped-element filters are often preferred because they are smaller and less expensive. Overall, as long as these design conditions are respected, standard components are usually sufficient and can be integrated into a system without significant challenges.
But this becomes a challenge in modern defense and aerospace designs, because performance requirements here often demand a combination of characteristics from both ends of the spectrum.
A design may need the thermal stability and power handling normally associated with larger cavity filters, yet only have room for a much smaller surface mount part. In such cases, off-the-shelf options force a trade-off: one part may fit the space but cannot handle the heat, while another meets performance requirements but is too large to accommodate.
Custom microwave components allow you to optimize these competing requirements by combining the most suitable features of different technologies into a single design.
This blog explains how custom microwave solutions can address the size, performance, and thermal limitations of standard components used in modern defense and aerospace applications.
Modern defense and aerospace systems must deliver high performance while operating within strict size, weight, and power constraints (SWaP). RF front-end filters, for example, often need to handle high power while maintaining tight control of the signal, a function traditionally served by cavity-based designs. In many platforms, however, the available space only supports a small surface-mount implementation, creating tension between electrical performance and physical size.
A smaller filter tends to have a lower Q-factor, meaning it is less precise at selecting the desired signal, and it also has higher insertion loss, which weakens the signal as it passes through. To compensate, the system may need stronger amplifiers, which consume more power and generate more heat.
Although small filters may fit within the allotted board area, they can struggle under high-power operation, potentially overheating or failing to adequately block unwanted signals, issues that are especially critical in demanding military systems.
Commercial off-the-shelf (COTS) components serve general applications with established requirements and are optimized by manufacturers for yield and broad market compatibility. They rely on standard dielectric constants, fixed housing geometries, and simplified internal topologies to keep production efficient. This approach works well for stationary telecom equipment or general instrumentation, where space and airflow are plentiful.
However, in defense and aerospace systems, components must deliver maximum performance in a very small space while keeping power consumption and heat under strict limits. In addition, platforms such as missile seekers and airborne electronic warfare systems operate in harsh environments that exceed the intended limits of most commercial components.
When a standard part nearly meets your requirements but doesn’t fit perfectly, your team will need to find workarounds for its limitations. They may need to design custom mounting brackets for a bulky filter or add extra thermal management to keep a smaller filter from overheating. These workarounds can add weight to the system and demand more engineering effort. While the component itself may be inexpensive, managing these integration challenges can extend your program schedule and increase overall resource needs.
When space is limited and power demands are high, you can’t rely on standard catalog parts to meet your system’s needs without workarounds. Instead, your team can treat the filter as a custom, integrated assembly, combining multiple technologies to leverage their strengths rather than searching for a single off-the-shelf solution that rarely exists.
For example, your team can use small lumped elements to conserve space while integrating high-performance dielectrics or metallic structures to achieve the power handling and signal quality of a larger component. This approach keeps the filter sharply selective and energy-efficient while fitting into a compact footprint, so you don’t have to compromise performance for size.
Choosing a custom solution can also reduce the work required by your team during system integration. You avoid spending billable hours designing complex mounting brackets or adding thermal management just to make a standard part survive demanding conditions. In short, this approach shifts the technical complexity from your team to the component manufacturer.
While standard components effectively support many RF architectures, certain high-density defense applications may benefit from additional design flexibility. In cases where a catalog part only partially meets the system’s size, thermal, or signal requirements, engineers may need to implement extra integration measures, which can reduce some of the initial efficiency gains.
Rather than choosing between a small component that can’t handle high power and a large component that won’t fit, a bespoke microwave solution can combine multiple technologies (e.g., lumped elements, cavity-like structures, advanced dielectrics) to address both requirements at the same time. The filter can be physically small (fit the PCB or module) while still handling the required power and maintaining signal quality (high Q-factor, low insertion loss).
So, instead of your engineers spending time adding extra cooling, redesigning housings, or overcompensating for a part that doesn’t quite meet specs, this complexity is addressed in the component itself during its design phase.
Q Microwave helps deliver this engineering advantage. We design microwave components tailored to the specific requirements of your mission and application. This approach helps protect your schedule, preserves your SWaP budget, and supports system performance as intended through:
Partner with Q Microwave today to streamline development and get a filter that fits, performs, and integrates seamlessly.
Q: At what point does the cost of integrating a standard COTS part exceed the cost of a custom solution?
A: The "tipping point" usually occurs when your engineering team has to modify the system to accommodate the component. If you are designing specialized mounting brackets, adding secondary thermal management systems, or redesigning the chassis just to fit a standard catalog filter, you have likely exceeded the cost of a custom design. A custom RF component design absorbs that complexity internally, helping preserve your system architecture and saves expensive integration hours.
Q: How does a custom design physically resolve the conflict between small size and high Q-factor?
A: We do not rely on a single topology. A standard surface-mount part might use basic ceramic resonators that suffer from high insertion loss. In a custom design, we can integrate high-performance dielectrics or metallic structures, typically found in larger cavity filters, directly into a compact surface-mount package. This allows the component to maintain sharp selectivity and handle higher power levels without requiring the physical volume of a traditional connectorized box.
Q: Can a custom surface-mount part genuinely match the thermal stability of a larger cavity filter?
A: Yes, because the materials are selected for your specific environment rather than general manufacturing yield. Standard parts use materials optimized for broad commercial use, which may drift under the extreme temperature cycling of a missile seeker or airborne jammer. Custom filter manufacturing allows us to use thermally stable materials and specific housing geometries that dissipate heat efficiently, helping ensure the filter remains stable even under high-power loads in a confined space.