Anatech Electronics manufactures standard and custom LC Bandpass filters and Duplexers/Diplexers from 0.1 MHz – 20 GHz.
K&L’s WSD-00420 ESMR duplexer is reaching thresholds of this technology with it’s extreme low insertion loss and tight rejection at 861.5 MHz this filter has been optimized for performance and cost
Anatech provides ceramic and cavity filters for INMARSAT communication applications

As demands increase for media rich applications and autonomous vehicle technologies in existing microwave bands, MtronPTI offers V-band and E-band Microwave Duplexers as a solution to enable gigabit-per-second data rates in backhaul data streams. The V-band duplexers cover 57.0 to 64.0 GHz and can deliver more than 2 Gb/s of secure data, while the E-band diplexers cover 71 to 86 GHz and deliver up to 10 Gbps of secure data, even in a dense urban environment.

2450 / 5512 MHz Diplexer (2450DP15B5512E) by Digi-Key.

The MtronPTI LF9422 L/S Band LC Filter Diplexer is custom designed for small form factor UAV-ISR platforms. Unlike open frame designs, the 1” x 1” wash-proof surface mount package is sealed, allowing automated assembly with no drift after board cleaning.

Diplexers and multiplexers are used to either separate or combine two different frequencies that are similar in range to one another. While bandpass filters can also be used to combine and separate signals, they’re only ideal for use with frequencies that are far apart from one another.

Narda West’s AMPS Band High Isolation Duplexer provides highly selective receive/transmit combining