Frequency Filters : Resolve your RF interference problems
ZCG Scalar are the Australian distributor of frequency filters manufactured by DCI Digital Communications Inc in Canada. DCI specialise in Radio Frequency Interference (RFI) products which reduce interference problems in the 30 MHz to 6 GHz range.
The products DCI design and manufacture include VHF and UHF bandpass filters, lowpass filters, duplexers, diplexers, multiplexers, combiners, tower top low noise amplifiers, discrete component filters, receive multicouplers and WiMax filters.
Quality filters for every RF interference issue
DCI's strength in this market is the design and fabrication of custom devices where your needs are not met by "off the shelf" models.
ZCG Scalar will work with you to define your specifications and provide custom solutions at reasonable prices. Specific solutions are available for specific RFI problems.
These high performance RF filters are made with steep skirts, low SWR and can accommodate low and high power applications.
There are frequency filter solutions available for numerous applications :
Television Broadcasting, digital and analogue
Digital Mask Filters are required to reduce the bandwidth of digital TV signals to conform to communication authority requirements. As each transmitter has its own characteristics, the filters are custom designed to work with your transmitter so that the combination of transmitter and filter conforms to all requirements. TV filters can be optionally combined for multiple channel use on one antenna.
FM Radio Broadcasting
FM Filters are used to reduce the bandwidth of the transmitter signal and, therefore, interference to other services. Two or more filters can be combined into a diplexer or multiplexer so multiple transmitters can share the one antenna.
Cellular Mobile Phone Providers
Filters on the reverse path (RX) of the Base Tranceiver Station (BTS) have been very successful in reducing dropped calls, reducing interference and increasing sensitivity. They are usually provided on an "as needed" basis to address unique interfering signals at a specific site.
Lowpass filters are helpful in removing in-band harmonic interference from nearby transmitters. The low pass filter would be added to the offending transmitter.
Wi-Fi Providers
Wi-Fi and ISM filters are high quality machined aluminum or silver plated filters available in a variety of configurations.
Bandpass filters can improve radio reception by reducing interference. Improved reception will increase data transfer rates and coverage distance. The filters pass a band of frequencies (channels) and reduce signals (interference) outside of the filter's pass band. They will not reduce interference from other signals or users on your channel.
Paging Companies
The most common problem for paging companies is complaints that they are interfering with other services.
Lowpass filters on paging transmitters reduce harmonics by about 35 dB, while having no effect on the paging transmitter signal since the filters have less than 0.15 dB of loss.
Bandpass filters can help to remove paging interference to other sites.
Military and other users
DCI can design non-standard specialised filters to meet the unique requirements of the military. The filters are anodized and weather resistant for rugged, corrosive and wet environments as frequently encountered by fixed and mobile military applications.
Other users of DCI filters include amateur radio operators, airports, railways, road transport companies, medical facilities, audio recording and satellite groups.
The DCI Product Range
The range of products DCI Digital Communications design and manufacture are :
Bandpass Filters
VHF and UHF bandpass filters from DCI are available in 4-, 6-, 8- or 10-poles, depending on how much rejection is required. DCI filters are passive and can be used in both the TX and RX pass. They are DC-grounded on both inputs and outputs for additional lightning protection. The filters come standard with type “N” connectors, with other types of connectors being optional.
Lowpass Filters
Lowpass filters are typically used on transmitter outputs to reduce harmonics and broadband noise, and on receiver inputs to reduce fundamental overload from higher frequency transmitters. DCI lowpass filters have extremely low loss (0.1 dB) with an estimated power handling capability of 2 KW.
A lowpass filter serves as excellent insurance against interference to other services. For example, VHF can interfere with UHF, and UHF can interfere with Cellular.
Duplexers and Diplexers
Duplexers are used to connect broadband transmitters and receivers to the same antenna for simultaneous operation.
They provide excellent isolation between RX and TX, suppress intermod from adjacent signals and provide additional lightning protection with DC grounded inputs.
They are useful where the TX and RX use a range of frequencies such as multi-channel trunked systems or video repeaters
DCI broadband duplexers have steeper skirt selectivity than most duplexers on the market and are used where 800 MHz trunking systems coexist with cellular systems. They provide excellent separation between services, reduce broadband transmitter noise and reduce desense.
Each duplexer is made up of two bandpass filters linked together into a 3-port device with a cable harness.
Multiplexers (TX and RX Combiners)
DCI makes a wide variety of transmit combiners linking as many as 8 bands to one antenna.
These units are used where multiple transmit and receive bands exist and there are multiple receivers and/or transmitters in each band. They allow the use of multiple transmitters and receivers on one antenna while providing considerable protection from other interfering signals.
Multiple window filters are made up of three or more band pass filters linked together with a cable harness that is specifically phase-matched.
Tower Top Low Noise Amplifiers
DCI tower top amplifiers achieve excellent sensitivity by using very efficient Low Noise Amplifiers (LNA) while maintaining better than average intermod immunity through the use of very sharp, low-loss filtering.
Each unit consists of a low-loss filter and low-noise amplifier, a transfer switch, and lightning protection on both the input and output coax.
The units are housed in a weatherproof aluminum enclosure that bolts to the tower leg.
Discrete Component Filters
Discrete component filters provide a wider variety of filter types and bandwidths than is attainable with cavities or helical resonators.
They can be made in low pass, high pass, bandpass and bandstop versions at almost any frequency and passband width. These filters are typically used for research and test bench applications.
Receive Multicouplers
Receive Multicouplers (RMC's) are used to achieve maximum sensitivity when multiple receivers are connected to one antenna. Typically a band pass filter is included for increased sensitivity and intermod immunity. RMC's can have multiple tower top Low Noise Amplifiers for optimum sensitivity.
WiMax Bandpass Filters and Duplexers
DCI manufacture filters in the common WiMAX bands. The filters are of a milled cavity design and therefore high in Q and selectivity. The filters are available in bandpass, duplex, diplex and multiplex designs. The variety of bands, poles and extras is large, and therefore all WiMAX filters are made to order.
For more detailed product information, visit the DCI Digital Communications website here »