UHF-Band Bandstop Filter: The Basic Configurations Of UHF-Band Band Stop Filters

In the world of electronics and communications, frequencies can be quite tough to comprehend. But if you look at how things work seamlessly, despite the complexities involved, you’ll be so surprised to know how satellites, aircraft and ship radars, as well as mobile phones and devices (and others) do their jobs, thanks to the frequencies they’re using to transmit and receive signals! And who makes sure that only the right frequencies pass through a given band? Its’ the job of electronic filters. And in the very busy UHF, or ultra high frequency band, it’s the UHF-band band-stop filters who make sure everything’s in “order”. Here’s how this filter works.

The Standard Configurations Of Band Stop Filters

Band stop filters are unique when compared to other types of electronic filters. It’s because this type of filter is created by combining low pass and high pass filters. It is also made using parallel connections, and not a cascading connection. The filter name also indicates that it stops a particular band of frequencies. Thus, in the UHF realm, UHF-band band stop filters play the roles of traffic enforcers, or bar/night club bouncers!

And because band stop filters pass above and below a particular range of frequencies whose cut-off frequencies are pre-determined, while eliminating or not allowing other frequencies to pass, they’re referred to as “band reject” or “band elimination” filters. Any of the frequencies that are in-between the two cut-of frequencies are also attenuated.

The UHF Band’s Useful Applications

The ultra-high frequency band is not just for transmitting TV signals over vast distances, but they’re also used for a host of other helpful, and profitable, applications.

For starters, the UHF radio spectrum range refers to the band extending from 300 megahertz (MHz) to 3 gigahertz (GHz), are also the frequency of choice of cellular telephone services, paging systems, satellite TV broadcasting, as well as 3G (third-generation) wireless services.

And since this frequency range is high, and the band is immensely wide too, it will be practical to employ wideband modulation and spread spectrum techniques. All the sub-bands and channels within the ultra-high frequency spectrum are allocated and supervised by the International Telecommunication Union.

The UHF band also has two sections, the “low-band” and “high-band” range. The low band UHF range has two overlapping bands, and these are low (from 450 to 536 MHz) and high (from 470 to 806 MHz), and the main users of these bands are land-based mobile radio and pagers, as well as UHF channels 14 to 69 (470-806 MHz).

The UHF’s high band range is the one above 900 MHZ, and the main users are studio-to-transmitter links or STL’s. And just like the very high frequency (VHF) band, licensing is a must in the UHF band too, and the required minimum ¼ wavelength antenna size for UHF radio waves is from 4 to 7 inches.

With the UHF band getting busier and busier each day, it’s imperative that the UHF-band band stop filters used for TV or data transmission satellites, radar systems and even mobile phones or pagers have the capability to effectively pass frequencies within its range, while at the same time attenuating, or blocking the entry of out-of-range frequencies.