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WM490: Difference between revisions
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The '''Tektronix WM490''' is a series of waveguide mixers for 490-series spectrum analyzers, e.g., the [[7L18]], [[492]], and [[494]]. | The '''Tektronix WM490''' is a series of waveguide mixers for 490-series spectrum analyzers, e.g., the [[7L18]], [[492]], and [[494]]. | ||
As described in Spectrum Analysis Utilizing Waveguide Mixers, the application note [[media:26W-5390.pdf|26W5390]] states that whether a measurement is made at audio frequencies or millimeter wavelengths, the spectrum analyzer is used to measure amplitude vs. frequency. Typical measurements include spectral energy distribution or signature of the energy source. This can be as simple as measuring harmonic levels of a continuous wave source to a more complicated occupied bandwidth measurement of a digital microwave transmission system. | As described in "Spectrum Analysis Utilizing Waveguide Mixers", the application note [[media:26W-5390.pdf|26W5390]] states that whether a measurement is made at audio frequencies or millimeter wavelengths, the spectrum analyzer is used to measure amplitude vs. frequency. Typical measurements include spectral energy distribution or signature of the energy source. This can be as simple as measuring harmonic levels of a continuous wave source to a more complicated occupied bandwidth measurement of a digital microwave transmission system. | ||
Actual spectrum analyzer measurements at millimeter wavelengths differ from lower frequency measurements in the transition from coaxial cables to waveguides. Most spectrum analyzers have an internal mixer upper frequency limit of 21 to 22 GHz, and utilize a type "N" RF input connector. | Actual spectrum analyzer measurements at millimeter wavelengths differ from lower frequency measurements in the transition from coaxial cables to waveguides. Most spectrum analyzers have an internal mixer upper frequency limit of 21 to 22 GHz, and utilize a type "N" RF input connector. | ||
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When the requirement measurement is above 22 GHz, some type of external mixing is required. Current techniques utilize harmonics of the spectrum analyzer first sweeping LO and an external harmonic waveguide mixer covering the designer frequency range. The mixers extend the frequency range of measurement up to as high as 325 GHz. Each mixer covers a separate frequency range, typically about two thirds of an octave. | When the requirement measurement is above 22 GHz, some type of external mixing is required. Current techniques utilize harmonics of the spectrum analyzer first sweeping LO and an external harmonic waveguide mixer covering the designer frequency range. The mixers extend the frequency range of measurement up to as high as 325 GHz. Each mixer covers a separate frequency range, typically about two thirds of an octave. | ||
Note: The MIL-F-39000/3C which describes flanges for double-ridge waveguide was cancelled without replacement on January 20, 2009. | Note: The [[media:MIL-DTL-39000C.pdf|MIL-F-39000/3C]] which describes flanges for double-ridge waveguide was cancelled without replacement on January 20, 2009. | ||
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