Customized RF Components and Microwave


RF Filter for Radio/Telecommunication Transmitter & Receiver to omit interference

RF systems operate at Radio Frequency, range varies between 30 kHz and 300 GHz. In particular, the VHF (very high frequency) 30 MHz to 300 MHz and UHF (ultra high frequency) 300 MHz to 3000 MHz frequency ranges are the most widely used in FM, television broadcasts, land mobile, maritime mobile communications, ground-to-air, air-to-air communications, two-way radios, satellite radio, weather radio, remote control system and amateur radio.

In Terrestrial, Marine and Air communication networks and related RF modules the transmitters and receivers are indispensable. RF transmitter receives serial data and transmits it wirelessly through its antennas connected. And then transmitted data is received by RF receiver which is operating at the same frequency as like the transmitter.


Interference is at least an occasional problem with most types of radio and wireless devices. The effects of interference range from being a minor annoyance to making the wireless system completely unusable. Two types of interference are common occurred in radio and telecommunication transmitter and receiver: Radio Frequency Interference (RFI), and Intermodulation interference.

RFI is caused by radio and TV transmitters, communications equipments, and other types of device that generate radio frequency power when they're operation. As like direct interference when occurs there is another strong radio signal on the frequency used by the wireless system. E.g. TV transmitter are very powerful and can affect radio communication systems at distances of 100 miles (160 km) or more. When interference happend, the first step should be to confirm whether the radio communication systems working frequency is on local TV channel in use in the area. It is a serious problem that must be corrected in order for the radio communication systems to be fully usable.

Intermodulation interference is caused by in the wireless receivers by the combination of two or more strong radio interfering signals. The interfering signals mix together in the wireless receiver to generate an internal signal which is close to the frequency of the receiver; also it caused by the signals either from other wireless transmitter combines with a strong local TV signals. Such internally-generated signals would interfere on another wireless system normal operation. General resolving intermod problems requires that one of the frequencies involved to be changed. However it is quite complicated and time wasted on the entire design concept.

How to find a efficient method to resolve the interference problem is always an issue for engineering and designer in wireless system. In order to keep the system overal design architecture not changed too much, to install or mount RF filters into the front-end circuit and filtering interference signals in transmitter and receiver would be very nice solution.

Temwell has extensive experience in designing and manufacturing RF Filter. We sort several classic application frequency bands in VHF and UHF, by Temwell designed Bandpass Filter, on the following table.

A. Frequency: 68-88MHz Spec (Freq / BW / IL) Size (LxWxH)   Accepted Type
TT67427B1-78M 78MHz / 20MHz / 2.5 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF64389B-78M 78MHz / 20MHz / 2.5 dB TF (30.5x7.6x12.5) Pin Type / Module Type

B. Frequency: 88-108MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT6388E-98M 98MHz / 20MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF6488E-98M 98MHz / 20MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type

C. Frequency: 108-128MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT67695B1-118M 118MHz / 20MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF69695BF-118M 118MHz / 20MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type

D. Frequency: 118-138MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT67159B1-128M 128MHz / 20MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF69159B1-128M 128MHz / 20MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type
E. Frequency: 136-174MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT63220B-155M 155MHz / 38MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF64220B-155M 155MHz / 38MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type

F. Frequency: 148-174MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT63213B-161M 161MHz / 20MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF64213BF-161M 161MHz / 20MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type

G. Frequency: 174-216MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT63212B-195M 195MHz / 42MHz / 1.5 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF64216B-195M 195MHz / 50MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type
H Frequency: 215-270MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT67853B-240M 240MHz / 60MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF69853B-240M 240MHz / 60MHz / 2.0 dB TF (30.5x7.6x12.5) Pin Type / Module Type

I. Frequency: 290-380MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT67869B-350M 350MHz / 90MHz / 1.5 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF69869B-350M 350MHz / 90MHz / 1.5 dB TF (30.5x7.6x12.5) Pin Type / Module Type

J. Frequency: 380-500MHz Spec (Freq / BW / IL) Size (LxWxH)  Accepted Type
TT6395F-440M 440MHz / 120MHz / 2.0 dB TT (22.8x7.6x12.5) Pin Type / Module Type
TF6495F-440M 440MHz / 120MHz / 1.5 dB TF (30.5x7.6x12.5) Pin Type / Module Type

66-88 MHz for PMR (Private Mobile Radio) trunking network, 88-108 MHz for FM radios station, 108-128 MHz for AM (air-ground voice communication signal) radio station, 118-138 MHz for aircraft radar, 136-174 MHz for radio transceiver, 148-174 MHz for maritime mobile, 174-216 MHz for radio microphone, 215-270 MHz for fixed mobile and broadcasting, 290-380 MHz for land mobile radio, 380-500 MHz for TETRA (Terrestrial Trunked Radio) as digital trunked mobile radio using.

The demo Bandpass filters are high attenuation and low insertion loss. They provided two package types: Pin (thru-hole) and Connector (SMA or N) for your flexible integration design. In case you need higher frequency more than 2.6 GHz, wider bandwidth or higher power more than 20 Watt, we have Cavity & LC filter to support. All products are made in Taiwan, quality reliable, see Certificates.

If you have more views and thoughts regarding customized RF filter in your transmitter and receiver design, please Contact us.