EMI Filter:
The capacitor used in Filter just as ceramic EMI filter.It also called Feed-thru Capacitors,Feed Through Capacitor,Feed-thru Filter,Feed Through Filter,Feed-thru Condenser,EMI Feedthru. because of its physical structure.
Feed-thru Capacitor's inductance smaller than usual capacitor,so resonance frequency by itself are high.meanwhile,itprevent the high frequency signal direct couple from input to output for Feed Through design.It supply better depressioneffect during frequency 1GHz because of low-pass together with high-cut.
It is the most simple of feed through structure that connect internal and external electrode with ceramic form one(C type) or two capacitor(Pi type).The capacitance arrange from 10PF to 4700PF,the rated voltage can achieve 2000VDC.Discoidal Capacitor didn't show appearent resonance frequency by itself at 10GHz,because it has the coaxial strcuture.
Feed-thru Capacitor's dielectric is ceramic,but ceramic capacitor's capacitance will change by environmental temperaturechangable,capacitance changable will influence filter's cut-off coefficient of filter.The ceramic capacitor dielectric fix itsself capacitance temperature change.So select the adequate ceramic dielectric is very important.usual ceramic dielectric and its capacitance temperature change as follows:

Dielectric Feature		COG(NPO)	X7R	Z5U	Y5V
		super stable	stable	usual
Working  Temperature		-55℃---+125℃	-55℃---+125℃	-10℃---+85℃	-30℃---+85℃
Cap. Temp. Change(max)		0±30ppm/℃	±15%	-22%---+56%	-22%---+82%
Insulation Resistor(IR)		≥104MΩ	Cr ≤ 25nF   IR ≤ 4000MΩ Cr ≤ 25nF  IR* ≤ 100S
Dissiaption Factor(tanб)		Cr>50pF≤0.015 Cr≤50pF≤0.015 （15/Cr+0.7）	＜0.025	＜0.030	0.050
Dielectric Strength	working voltage	apply working voltage times(apply time 5 seconds,current 50max)
	200V	X2.5	X2.5	X2.5	X2.5
	500V	X1.5	X1.5	X1.5	—
	＞1KV	X1.5	X1.25	—	—
Digestion Decimal Logarithm Time		0	1%	6%	6%

Filter Inductor:
Filter inductor is used to ferrite materials,it can get together with the Feed-thru Capacitors conveniently,form the composite filter,in the filed of high characteristic filter,it also use wire-wound inductance.one point:Ferrite materials will appear magnetic saturation in high current,and reduce the filter function.

Filter Installation type:

H:Solder-in  type Filter                              L:Screw Threaded type Filter