Diplexers, Triplexers, Multiplexers

Low insertion loss diplexers and triplexers are essential for many of today’s defense platforms and modern wireless environments that require high spectral fidelity. Low insertion loss diplexers and triplexers (1 dB) help receivers detect and process low-power targets, as well as discern targets of interest in interference-heavy environments. Spectrum Control offers low-loss multiplexer designs to help identify weak communication transmissions and recognize valuable intelligence signals in a crowded spectrum.

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Our database of low-loss diplexer and triplexer designs helps eliminate the need for additional gain when size, weight, and power (SWaP) initiatives are in place. Spectrum Control engineers incorporate innovative design techniques, including:

Iris coupling to reduce housing size and weight
Incorporated cross-coupling to create transmission zeros for improved out-of-band rejection
Spectrum Microwave’s pseudo-elliptic designs that use cross-coupling to achieve enhanced rejection performance
Integration of multiple topologies within a single package for broad frequency coverage

Spectrum Control consistently rises to engineering challenges. When a request for a diplexer with extremely low insertion loss, extremely high rejection, and a housing that fit a narrow opening, our engineers responded with a design incorporating unconventional cross-coupling that exceeded the requirements. We evaluated all applicable topologies to optimize performance without compromise. Suspended substrate diplexer and triplexer designs are ideal for broadband applications, offering superior design flexibility and low insertion loss.

High-power notch diplexers is another example of delivering customer-specific solutions. Designs that require rejection of two high-power tones, we developed a pole-placed highpass–lowpass notch diplexer that provided the required rejection without increasing loss on either side of the passband.

Novel Packaging Custom Housings

Novel Packaging

Because of the customer’s preexisting interface conditions, the output ports of this diplexer were required to exit the bottom of the housing. Our engineers designed the diplexed output connectors accordingly, ensuring precise alignment with the customer’s existing connectors.

Versatility is a hallmark that sets Spectrum Control apart from other filter companies. Drawing from a wide range of topologies, our engineers select the optimal approach for peak performance, including iris coupling to reduce unit size and silver plating to lower insertion loss.

See Custom Housings tab for more of our capabilities.

Custom Housings

Spectrum’s pseudo-elliptic designs incorporate cross-coupling to generate strategically placed transmission zeros, significantly enhancing rejection performance. Through precise control of resonator coupling paths and electromagnetic interactions, our engineers achieve steep roll-off characteristics and superior close-in attenuation without increasing insertion loss or filter complexity. This methodology reduces the number of poles required to meet rejection targets, enabling smaller, lighter designs while preserving high Q and stable passband performance.

This high-power notch diplexer is another example of Spectrum Microwave delivering customer-specific solutions. The customer required rejection of two high-power tones, so our engineers developed a pole-placed highpass, lowpass notch diplexer that delivered precise attenuation at the specified frequencies without increasing insertion loss on either side of the passband.

By carefully controlling pole placement and coupling structures, the design achieved the required rejection while maintaining passband integrity, power handling capability, and overall system efficiency.

This high-power notch diplexer is another example of Spectrum Microwave delivering customer-specific solutions. The customer required rejection of two high-power tones within a tightly constrained frequency plan, demanding both precise attenuation and minimal impact to adjacent passbands. To meet this challenge, our engineers developed a pole-placed highpass–lowpass notch diplexer that provided the exact level of rejection required without increasing insertion loss on either side of the passband.

By carefully optimizing pole placement, coupling coefficients, and resonator interactions, the design achieved sharp attenuation at the specified frequencies while preserving passband integrity and maintaining high power-handling capability. The result was a robust, application-specific solution that met stringent electrical and mechanical requirements without compromising overall system performance or efficiency.