# Interdigital Bandpass Filter FEATURES:
•Low Insertion Loss
•Low VSWR
•Flat Frequency Response
•2% TO 40% BANDWIDTH

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## Description

FI SERIES
 MODEL NUMBER FREQUENCY RANGE (GHz) 3dB* BANDWIDTH % OF F.C. NUMBERS OF* SECTIONS VSWR OVER* BANDWIDTH RANGE* Deg. FI 1 To 18 2% To 40% 4 To 15 1.50:1 To 12.4 0 C To +50 C

* Custom Design Available. Contact Manufacturer For Other Specifications *

GENERAL SPECIFICATIONS:
Impedance : 50 Ohms
Power Handling : 50 WATTS
The Maximum Insertion loss at a center frequency can be determined using the following formula :
Insertion Loss = (K) (0.5 + No. of Sections) + 0.1 / 3 db Bandwidth
Where the insertion loss constant (K) = 0.85 Up to 18.0 GHz Example : Center Frequency = 8000 MHz,
3 db BandWidth = 1700 MHz
Number of Sections = 8
The db BandWidth = (100 (1700)  / 8000 = 21.25%
Therefore Insertion Loss = (0.85) (0.5 + 8) + 0.1 / 21.25 = 0.44db
The Attenuation Range can be determined using the following formula :Attenuation Range = 3 db BW @ Fc = Reject Freq. – Fc / 3dbBandWidth

Example : Center Frequency = 8000 MHz, 3 db BandWidth = 1700 MHz
Number of Sections = 7
To find the Attenuation at 5900 and 9000 MHz :
The 3 db BandWidth from the Fc = 5800 – 8000 / 1700 = 1.294
The 3 db BandWidth from the Fc = 10200 – 580 / 1700 = +1.294
VSWR Bandwidth : Refer to Graph 3

ORDERING INSTRUCTIONS
FI-XXXXX-XXXX-XX-XX
Combline InterDigital—–FI-
Center Frequency (Fc)——XXXXX-
Minimum 3 db Bandwidth————–XXXX-
Number of Sections—————————-XX-
Input Connector————————————–X
Output Connector—————————————-X

MECHANICAL OUTLINE: Consult Manufacturer For Specific Configurations and Mounting Hole Locations