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Specifying Cavity Filters

Cavity Filter Part Number Description

Cavity Filter Part Number Description


1. Number of Sections

2. Series and Package Size

3. Center Frequency, MHZ

4. Bandwidth and Code (3dB BW Standard)

5. Input Connector

6. Output Connector (if different from Input)

(1)Requires Minimum Cross Section of 0.88"
(2) Requires SMA Removable Connectors at High Frequencies

Bandwidth Designator
3 dB /(blank)
1 dB /A
equi-ripple /R
special /X
Connectors
Connector Type Designator
BNC Female (1) B
BNC Male (1) BM
Blind Mate BP
N Female (1) N
N Male (1) NM
RF Pin (2) P
SMA Female S
SMA Male SM
SMA Removable SR
Special X
TNC Female (1) T
TNC Male (1) TM
Overview
Specifying Cavity Filters
Charts


Calculating Number of Sections


The following curves show the stopband frequencies normalized to the 3 dB bandwidth for filters with 2 to 13 sections.
A ratio of stopband frequency to 3 dB bandwidth is used.

The curve given on the right shows a slightly asymmetric frequency response resulting from the circuit used.
Other schematics may be utilized to yield different attenuation characteristics (i.e. steeper on the high frequency
side of the passband and shallower on the low side).

Example:
A CF-Series filter has a center frequency of 1000 MHz and a 3 dB bandwidth of 10 MHz. A stopband attenuation of 60 dB is required at 980 MHz and 1030 MHz.

The percentage bandwidth is 1%, calculated as follows:

Calculating Number of Sections Example

For the first stopband requirement we have:

Number of 3dB bandwidths from center frequency =



From the CP/CF series attenuation curve, we find that a minimum of 7 sections are required.

The second stopband requirement is: Number of 3dB bandwidths from center frequency =

From the CP/CF series attenuation curve, we find that 5 sections minimum are required.

The greater number of sections must always be used to insure full specification compliance; therefore, a 7 section should be used.

Insertion Loss Calculation - Cavity

Knowing the number of sections, center frequency and bandwidth of the filter, insertion loss may be calculated from the following formula:

Example: 5CF2-915/25-N
1. Percentage BW = 25 / 915 x 100 = 2.7%
2. Q from CF series curves = 2.9
3. Number of sections = 5
4.

Example: 9EZ6-8725/1375-S
1. Percentage BW = 1375/8725 x 100 = 15.8%
2. Q from EZ series curves = 1.1
3. Number of sections = 9
4.

CP and CF Series Attenuation Characteristics
 
  "Q" - CF,CP Series Narrowband Cavities
 
  "Q" - EZ and IZ Series, Wideband Cavities
 
  EZ and IZ Series Attenuation Characteristics

 

NARROW BAND - 0.5% to 4%
P/N  Freq-Range
(MHz)
% 3 db
Bandwidth 
VSWR
(Nominal)
Number of
Sections 
 Avg. Power
(Watts)
Operating
Temp. (Deg. C)
Relative
Humidity
 
CP  30 - 2000 0.5 - 4 1.5:1 2 - 6 10 -55 to +85  95%
CF2  500 - 2000 0.5 - 4 1.5:1 2 - 8 10 -55 to +85  95%
CF3  500 - 2500 0.5 - 4 1.5:1 2 - 8 10 -55 to +85  95%
CF4 2000 - 3000  0.5 - 4 1.5:1 2 - 8 10 -55 to +85  95%
CF6 2000 - 8000 0.5 - 4 1.5:1 2 - 8 10 -55 to +85  95%
CF7 4000 - 26000 0.5 - 4 1.5:1 2 - 8 10 -55 to +85  95%
See Cavity Filter Chart Section >


NARROW BAND [COMBLINE] - 1% to 25%
P/N Freq-Range
(MHz)
% 3 db
Bandwidth 
 VSWR
(Nominal)
Number of
Sections
Avg. Power
(Watts)
Operating
Temp. (Deg. C)
Relative
Humidity
 
 EZ3 500 - 6000 1 - 25 1.5:1 2 - 17 10 -55 to +85  95%
EZ4 1000 - 8000 1 - 25 1.5:1 2 - 17 10 -55 to +85  95%
EZ5  2000 - 12000 1 - 25 1.5:1 2 - 17 10 -55 to +85  95%
EZ6 4000 - 18000 1 - 25 1.5:1 2 - 17 10 -55 to +85  95%
EZ7 6000 - 26000 1 - 25 1.5:1 2 - 17 10 -55 to +85  95%
See Cavity Filter Chart Section >


WIDE BAND [INTERDIGITAL] - 25% TO 66%
P/N Freq-Range
(MHz)
% 3 db
Bandwidth 
VSWR
(Nominal)
Number of
Sections
Avg. Power
(Watts)
Operating
Temp.
(Deg. C)
Relative
Humidity
IZ3 500 - 6000 25 - 66 2.0:1 2 - 17 10 -55 to +85 95%
IZ4 1000 - 8000 25 - 66 2.0:1 2 - 17 10 -55 to +85 95%
IZ5 2000 - 12000 25 - 66 2.0:1 2 - 17 10 -55 to +85 95%
IZ6 4000 - 18000 25 - 66 2.0:1 2 - 17 10 -55 to +85 95%
IZ7 6000 - 26000 25 - 66 2.0:1 2 - 17 10 -55 to +85 95%
See Cavity Filter Chart Section >

Shock 10G
Vibration 20G
See the Cavity Outline Section for Outlines and Dimensions
Contact factory for specific requirements not listed above.

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