Phase2 Microwave have a wide range of VHF and UHF filters available using lumped element, helical and combline technologies.
Lumped element filters can be used for medium bandwidth applications but most of the applications are for narrowband comms which requires helical or combline cavities.
For single frequency applications helical filters can be used but lack tunibility so combline cavities are the norm.
ATC Cavites and Combiners
Air Traffic Control applications (both Civil and Military) lie between 118 and 400Mhz and use narrowband comms channels. Phase2 Microwave have developed high Q highly temperature stable cavities which can be operator set at any frequency in the VHF band. The terchnology can also be used for the UHF band. The cavities can be cable combined to form combiners.
VHF and UHF Digital TV Systems.
The global implementation of digital TV networks required new filtering solutions. Phase2 Microwave developed a range of high performance VHF and UHF filters and combiners which have been used in a continental roll out.
By careful design, and the use of stop poles, the filters can be tuned across while maintaining a constant bandwidth. Following waveguide multi-channel multiplexer design procedures the combiners used a cable connected manifold design and the dimensions were derived from using circuit theory. Up to 5 channels were combined, some of which were adjacent, without needing cable length iterations.