Lorch Microwave

Specifying Ceramic Filters

Ceramic Filter Part Number Description

1. Number of Sections

2. Filter Topology

3. Resonator Size

4. Center Frequency

5. 3dB BW

6. Termination Type

Reflow Profile

Overview

Specifying Ceramic Filters

Z-Pack Series™

Charts

Ceramic Electrical Performance
Parameter	Standard	Special
Frequency Range	400 - 3000 MHz	400 - 6000 MHz
Bandwidth	0.5 - 5%	0.1 - 25%
Number of Sections	2 - 6	2 - 8
Typical VSWR	2.0:1	<1.5:1
Power Handling	1 watt avg	Contact The Factory
Temperature Range	-20 to + 70 degs C	-55 to + 125 degs C

Filter Attenuation
The attenuation curves show the typical shape for the coaxial resonators for n=2 thru n=6. Use the formula below to determine the number of sections needed for the required attenuation.

Example:
Center Frequency = 1910 MHz
3 dB BW = 25 MHz
Stopband Frequency = 2000 MHz
Attenuation = > 50 dB

It is determined that 4 sections are required to meet >50 dB attenuation at 2,000 MHz.

Insertion Loss Calculation
Parameters needed:
1) Number of Sections (N)
2) Typical Resonator Qu (Qu)
3) Center Frequency (F_o)
4) 3 dB Bandwidth (BW)

Ql = (F_o)/BW
K = Qu/Ql

The formula is as follows:
l.L. = N*.63*20*LOG10(1+(1/(K-1)))

Example:
CF = 1910
3 dB BW = 25
Qu = 625 (6MM/Er 38.6)
N = 4

I.L. = 4*.63*20*LOG10(1+(1/(8.18-1)))=2.85 dB