300 mhz bandpass filter circuit
sorry about my bad english
I want a circuit for no-pass UHF filter. for RF antenna T.V
It must allow to pass VHF-L and VHF-H with high quality and not allow to pass UHF
thank you for answer
It looks as if a low pass filter will work. You need to specify the following:
source impedance
load impedance
frequency range in MHz that will be passed
frequency range that will be attenuated
the amount of attenuation in the attenuated frequency range.
use a vhf antenna
and you wont have a problem
as a properly designed n fed antenna will do this job for you
as long as you use a balun or a balanced feeder
there are a hotel and they want to control the content of channel .
there are 2 group of rooms , some rooms are allowed to watch VHF and some rooms allowed to watch VHF and UHF.
the allowed room may be changed, one day may be 40% of rooms allowed and one day may be 80% of rooms allowed.
hotel central ANT. for all room . ( Each room have 1 coaxial cabel)
I want to build a circuit that :
1- when circuit active , the user of room not able to watch UHF ( only can watch VHF)
2- when circuit is not active , user can see VHF and UHF channels.
thank you
A 5th order low pass filter will do the job but you must specify which TV or channelization standard is in use in your country to get better answer. Are S channels used in this hotel?
You need a simple low pass filter with one or two varactor diode. When varactor capacitance is high, the filter will kill the UHF and the poor customers will not be able to see the p*orn movies...
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You need a simple low pass filter with one or two varactor diode. When varactor capacitance is high, the filter will kill the UHF and the poor customers will not be able to see the p*orn movies...[/quote]
Yes ...you right ,but this is not for p*orn movies.
I need low pass filter to kill UHF band. <300 MHz
who can give me the circuit for this low pass filter?
You can use filter solutions software to design low pass filters.(search google)
You should use Helical low pass filter form at that frequency that is controlled by PIN diodes from remote current..
May I use L C lumped circuit on pcb? Do the pcb trace affect the frequency
response?
@leilarazavi2000
you can find free but still good filter design software here:
http://tonnesoftware.com/
Especially get friendly with Elsie, SVCfilter and Helical.
When you have the low pass filter that blocks signals above 300MHz you can use a pin diode switch as BigBoss mentioned, see this link on pin diodes:
http://www.microsemi.com/literature/pinhandbook.pdf
and refer mainly to Figs 2.6 and 2.7 and of course you have combine the filters and the diodes into a common matching circuit for 75 Ohms impedance.
If you feel like using a double amplifier optimised separately for VHF and UHF bands in an integrated circuit form with built-in switch for either band, see this link:
http://www.vishay.com/docs/85171/85171.pdf a data sheet for Vishay's TSDF12830YS. Using this amplifier you can compensate for a bigger insertion loss due to your filters and cables.
rgds, unkarc
May I use L C lumped circuit on pcb? Do the pcb trace affect the frequency
response?