What is Broadband Bandpass Filter?

Broadband bandpass filter, called Wideband bandpass filter, is an RF filter that has a parameter of wide bandwidth. It means that the Bandwidth value in the 5 main parameters of the RF filter (Center frequency, Bandwidth, Insertion loss, Attenuation value, and Return loss) can reach a maximum value. The pattern presented on RF filter curve graph looks very long and wide, therefore, it is described as Broadband Band Pass Filter or Wideband Band Pass Filter. Surely, Because Broadband Bandpass Filter has a very wide bandwidth value, the actual utility can really cover a wider protection range to avoid noise intrusion.

Broadband band pass filter is usually not limited by which filter basis to design, as long as its performance can meet the function of wide Bandwidth value, it can be called. Whether it is Cavity Filter, Helical Filter, Ceramic Filter, or Crystal Filter, the design basis can be called Broadband bandpass filter.

Professionally speaking, in the low frequency as VHF / UHF Band, there has a Bandwidth of 200M-300MHz, which can already be called a Broadband Bandpass Filter. But when it comes to L Band, S Band, C Band, X Band, and even above K Band and U Band , Bandwidth parameters will also increase, and may reach values above 20GHz. This depends on the overall parameters of the filter to develop the best filter design.

The advantage of using Broadband Band Pass Filter is that it can isolate the noise off from the a long range of frequency band you would like to cover. There is no need to set up an RF Filter for each small frequency band to eliminate noise.  

There are two difficulties in designing a Broadband Bandpass Filter. 

First, the Filter Bandwidth refers to the horizontal plane at the top of the filtered waveform. The longer and wider the top horizontal plane is, the wider the Bandwidth value is. Therefore, for a good Wide Band Bandpass Filter, the Bandwidth performance must be flat and wide, and it cannot show the jagged shape, or keep jumping up and down repeatly. Usually, it needs to be maintained within 0.5~1dB of variation, and even the highest level can be required to be within 0.2dB of variation. Because the coverage of the wide bandwidth is very long, it is easy to be interfered and the curve of the bandwidth will be deformed. So, the lower the degree of change, the flatter the horizontal plane and the better the performance, which is very difficult to achieve. Only an experienced design team could achieve the suitable proposal to you.

Second, the operation of RF filter includes two sections: Let the signal through and Isolate the signal. By the value of Bandwidth, you can know what frequency range signals can pass through, and by Attenuation value, you can know what frequncy range signals will be isolated. So, Bandwidth value and Attenuation value are two forces that appear to be pulling each other. The larger the Bandwidth, the lower the Attenuation energy, and the smaller the Bandwidth, the greater the Attenuation capacity. Therefore, under the wideband bandpass filter design, due to Bandwidth is very wide, which means there has a long rang of signal could go through , the Attenuation capability is greatly affected, so that Attenuation value in wide band bandpass filter is often insufficient to meet the purpose of isolating signals. In order to find the best balance point, an experienced RF Filter development team is needed to discover the best formula as quickly as possible to meet customer needs.

Temwell group as the worldwide expert in RF Filter design enables to provide the completed RF Filter design, including Broadband Filter. Alos, as Broadband Bandpass Filter requests high quality design technology and knowledge, Tenwell RF Filter design team has over 25years experience, which is your best choice. Click and visit our online catalog for more detail spec sheet. 

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