N6GKJ Interdigital Filter Page

This is a homebuilt Interdigital Filter. The filter is tuned to 1256 Mhz. It has a 3db bandwidth 10 Mhz. The insertion loss is 18.94 db and greater than 21db at the band edges. This filter was designed by me on my laptop and WB6ASU, Freddie built it. This filter has at least 80 tapped holes. It takes about 4 days to make this this filter
This sweep shows the bandpass and loss of this filter. As you can see it does have decent skirts. The filter is good for about 40db of rejection at 1270 Mhz and up
This sweep shows the insertion loss of the filter. The markers are set for set for 1254 Mhz, 1256 Mhz, 1258 Mhz respectively. the center hump is at 18.94 db. that is better than 1.5:1 SWR across the desired bandwidth of the filter.