Interdigital Filter for ADS-B

  

 

 

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A first attempt at a homebuilt interdigital filter for 1090mhz.

Based on the design and calculator at

Interdigital Bandpass Filter Design

 

 

Finally had a chance to do a wider scan of the filter's response. For a first attempt, I was pleased with the result, although the drop-off is a bit steep.

 

 

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November 2016 Rangeplot

from Planeplotter

 

 

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and from Virtual Radar Server

 

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outermost red ring is 300 nautical miles

 

 

Just prior to the end of November, the antenna and receiver were returned to the roof for the winter, protected by a heavy aluminium case.

October 2016 Rangeplot.

 from Planeplotter

 

 

(click to enlarge)

and from Virtual Radar Server

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Sometimes a single flight will register on VRS, but be barely visible on Planeplotter.

Since a power failure took out my outside receiver, most of October was recorded using indoor antennas. I hope to have the rooftop electronics reinstalled before the snow flies again.