The Knowles Precision Devices DLI brand of microstrip bandpass filters offers innovative filter topologies yielding excellent performance in a small footprint when fabricated on high DK temp stable ceramic substrate materials. Since our customers use our surface-mount filters in a wide range of applications, we’ve designed our devices so they can be used on most RF PCB materials. To ensure our customers achieve optimal performance and are successful with our filters, we have compiled a number of best practices and resources, which are outlined below.

Many microwave applications, such as repeaters, and electronic warfare equipment, require increased spectral resolution. This means these devices only need to look at a narrow slice of a given band. Filters that are optimized for the whole band, such us our planar microstrip devices, are too broadband for these applications. Likewise, traditional high Q filters, such as waveguide devices, are often too large to consider using in these types of applications.

With more than 2,000 satellites currently orbiting the Earth, and that number expected to quintuple in the next 10 years, the demand for space-ready components is exponentially increasing (Figure 1). At the same time, the technology needed to control and transmit satellite data has changed from mechanically controlled parabolic or dish technology to active electronically steered arrays (AESAs).

At Knowles Precision Devices, we support a wide variety of industries and applications with unique needs; the product catalog is constantly evolving to accommodate. We are often asked which frequencies we support. While our microwave products excel at higher frequencies, the catalog spans a wide range.

The US MIL-STD-461 specification manages electromagnetic interference emissions by setting limits on the levels that can be emitted from electrical equipment. This specification also sets regulation to control equipment susceptibility to external noise sources and establishes guidelines for properly measuring the relevant equipment features.

EMI filtering plays an important role in reducing noise that could interfere with other devices; in medical or defense applications, for example, false alarms due to external interference could be detrimental. Here, we will continue our EMI filtering exploration with application and installation considerations. For earlier reading, review EMI filtering basics and filter performance.

To comply with international legislation such as the EU Directive on EMC or the FCC, EMI filtering is an essential element of equipment design. Here, we will continue to explore EMI filtering through insertion loss and filtering performance.

The insertion loss performance shows signal attenuation at any given frequency. As a metric, the insertion loss performance is most useful as a guide in the filter selection process; the actual performance in service can vary depending on circuit characteristics.

In the race to implement mainstream 5G wireless communication, the world is waiting to see if this next-generation network will achieve a hundredfold increase in user data rates. This transformative technology not only boosts performance for the latest cell phones, but also for fixed wireless access (FWA) networks and Internet of Things (IoT) smart devices. In order to reach 10 Gbps peak data rates, the increase in channel capacity must come from somewhere. A key innovation at the heart of 5G is utilizing new frequencies greater than 20 GHz in the millimeter wave (mmWave) spectrum, which offers the most dramatic increase in available bandwidth.

With the ever-increasing use of electronic equipment comes a greater likelihood of interference from all the other equipment out there. In the same vein, we’re seeing more circuits, with lower power levels, that are easily disturbed; so, there’s a need to protect equipment from EMI (electromagnetic interference). In automotive or medical applications, for example, there can be no false alarms due to external interference. The level of uncertainty has pushed EMI compliance testing to the component level.

To meet international legislation such as the EU Directive on EMC or the FCC, EMI filtering is an essential element of equipment design. Introducing screening measures to case or cables, for example, may suffice in many instances, but you might need to introduce low-pass filtering for additional protection as well. Here, we will begin to explore EMI filtering and the terminology used in designing effective protection.

One of the questions we get asked regularly is:

‘why not just integrate a filter in the board stack?’

Our answer to this comes in two parts: First there are manufacturing tolerances to consider, and second there is size.