Base Station Filters without Irises

We present here a breakthrough technology which is very promising for building broadband dielectric resonator (DR) filters. To the best of our knowledge this is the only technology versatile enough to allow us to build filters at different centre frequencies and the bandwidths ranging from 30MHz to 80MHz in the same housing (there are seven pending patents on this technology). Unlike the contemporary DR filter technology, this also allows to tune high dielectric constant resonators easily. The resonators have the shape of truncated cone. The way the filter is tuned and the particular shape of the resonators enhances the electromagnetic field energy in between the resonators by favoring the continuous components of the fields thus helping the tuning and rejecting the discontinuous components. As a result our technology can easily realize and control the strong couplings, which are usually difficult to be achieved with the existing DR technologies. The measurements for a 10 pole 60MHz DR filter at PCS bands without irises are presented. The insertion loss (IL) is 0.34dB. A tunable version of it is also presented. The particular shape of the resonator and the particular layouts improve the spurious response. The measured spurious response of the 60MHz filter is more than 700MHz, without a clean up filter. The incorporation of the comblines to further improve the spurious does not affect the tunability. Response of a 5 pole filter with three DR and two comblines are presented. The same housing is tuned externally for 25MHz, 20MHz and 15MHz and after fixing the bandwidth at 15MHz the center frequency is shifted by 70MHz. Many of the ideas to our knowledge are presented for the first time