SUDOTECK released application FILCalc for iOS.
This application has 3 calculation functions for RF Engeneer .
Version 1.00

1) LPF calculator .
2) HPF calculator .
3) Air Coil calculator.

Picker Wheel Data setting interface is very simple for all functions .

DETAILS of functions
1)LPF [Low Pass Filter]
When you want to design LPF ,set the kind of filters using left wheel .
[C1.] ... chebychev filter of ripple 1dB MAX .
[C.5] ... chebychev filter of ripple 0.5dB MAX .
[C.2] ... chebychev filter of ripple 0.2dB MAX .
[But] ... Butterworth filter .
[Bes] ... Bessel filter .
And next whel select Number of components .

Cut-off frequency is set with numeric 4 wheels and "KHz" , " MHz" wheel .

An ideal characteristic is displayed on the screen.
And calculated value will displayed ata each components .

2)HPF [High Pass Filter]
When you want to design LPF ,set the kind of filters using left wheel .
And next whel select Number of components .

Cut-off frequency is set with numeric 4 wheels and "KHz" , " MHz" wheel .

An ideal characteristic is displayed on the screen.
And calculated value will displayed ata each components .

3)Air Coil calculator
To developing filter circuits , you will often need to make some coils .
The Air Coil is used for many filters .
You can calculate the value of coil using [D]iameter wheel and [L]ength and [N] turn of coil .

Info TAB will show you the responce of each kind of filters ,S11,S21 and groupe delay .
Tap [i] button , you can jump File calc support WEB .