Available Technology

Absorptive RF Filter for 20Ghz to 100GHz range - TRL 2

Reflectionless RF Filters for Radio Frequency Bands K, Ka, Q, U, V, E, W

What conventional RF Filters Provide

Conventional reflective filters do not dissipate spurious signals or added noise. Instead they build up as standing waves between the filter and the source and/or are radiated into the electronics housing, impacting the linearity, stability, and electromagnetic compatibility of the system. These effects often go unnoticed, but they can be important in some high-performance applications.

 

Background

High-frequency radio system engineers have numerous options for filtering requirements including topologies, synthesis equations and proven methods of implementation. Conventional RF filters focus almost exclusively on techniques that presume all circuit elements will be nominally-lossless, with a few exceptions. This presumption leads engineers to use filters with the following three properties:

  1. that minimize the passband insertion loss,
  2. show the sharpest possible transition between passband and stopband, and,
  3. reflect back to the source any out-of-band power rejections.

This causes the impedance mismatch to become maximized, but is accepted only because it occurs out of the operating band, since traditional thinking is that in-band performance is all that matters.  However, this is not always true.  If out-of-band signal power did not matter, why filter it in the first place?

 

Inventors: 
M A Morgan
Patent Number: 
US 9,923,881
Patent Status: 
Patent
Patent Issue Date: 
March 20, 2018
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