Figure 1


  • Bandpass, Highpass or Lowpass
  • Compatible with Microstrip, Coplanar Stripline, Lumped Well Grounded Element and Other Substate Environments
  • Fast Delivery
  • 200 MHz to 10 GHz
  • Rugged, High Q Construction
  • 3 dB bandwidths 3% to 200%
  • Gold Plated Brass Body
  • 50 Ohm, 70 Ohm, 93 Ohm
  • Pins or Tabs
  • 1.5 VSWR
  • Sealed (Glass Beads are used)
  • 3 Pole to 16 Pole
  • Lumped Element, spurious free design

DIF Filters are constructed using large cross-section inductors and single layer capacitors. This technique minimizes insection loss and maximizes ruggedness. Internal parts are firmly soldered, but are spot-potted for improved reliability and stability. All joints are microscopically inspected. These units are sealed. Glass-bead end connectors are used where round-pin terminations are specified. Epoxy sealing is used when flat tabs are required.

DIF Filters are easy to specify (see example below) and are suitable for channelized receivers, multipliers, amplifier output filters, etc. They may be readily multiplexed.

For the bandpass DIF Filters, low side attenuation will approximate 10% less (in db) than 0.1 dB Chebychev theoretical values down to 70 dB level. High side values will follow 10% less than a (N-1) pole .01 dB response, where N is the number of poles in the specific filter, down to at least the 60 dB level. The high-side selectivity characteristic can be improved on special order, if a non-monotonic skirt shape is allowable. DIF Filters can also be supplied with generalized Chebychev characteristics as described in the introductory material on lumped element and printed filters. Such filters are applicable to very wideband circuits and consist of lowpass-highpass combinations.

Picture of DIF filters

Center Frequency insertion loss can be calculated using the following formula:

EQ (1)         Loss = 7.5/BW  (.66 N - 0.83) 1/ (f o1/4)

Where          N = number of bandpass poles

                     BW = VSWR Bandwidth in percent (approximately 70% of 3 dB bandwidth for 5 pole, 90% of 3 db for 9 pole).

                        f o= center frequency in GHz

Note:         (f o1/4) = square root of square root of  f o

Channelized microstrip test fixtures are available to alleviate compatibility difficulties which have been common in the use of drop-in components. Installation of a typical filter is shown in Fig. 2. The channelized structure results in maximum input to output isolation.


  • = 1030 MHz
  • "Flat" Bandwidth = 80 MHz Minimum
  • 3 dB Bandwidth = 104 MHz Minimum
  • Required 60 dB = 392 Maximum
  • Bandwidth Number of Poles = 5(66 dB on a .01 dB Chebychev chart)
  • Percentage Flat  BW = ( 80/1030 ) x 100 = 7.76%
  • Insertion Loss = ( 7.5/7.76 ) (.66 x 5-.83) 1/ (1.03)1/4 = 2.4 dB 
  • Length = 1.5 inches (Table I)
  • Delivery = Start 30 Days
  • Part Number = DIF-1030-80-5

Figure 2

Figure 2 - FIlter Installation

DIF Filters can also be supplied with adaptor brackets enabling attachment of field replaceable connectors. Bandstop configurations are also available upon request.

Last Updated on Monday, 18 July 2011 14:18