Kristi Dhimiter Pance

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

Multiple Band and Multiple Frequency Dielectric Resonators Tunable Filters for Base Stations

The new tunable filter technology with truncated cone resonators is used here to realize multiple bands in different center frequencies in the same housing and with the same resonators. The bandwidth is varied from 20 MHz to 5 MHz and the center frequency is varied from 1930 MHz to 1990 MHz. The filter responses for 20 MHz and 5 MHz are achieved through complete external tuning and no cross couplings are applied. For the 15 MHz and 10 MHz responses the cross couplings are applied. The dielectric constant for the truncated cones and dielectric plugs is epsivr=35 and provides a very high Quality Factor Q and very good intrinsic spurious, which are so crucial for such a flexible design. To our knowledge this tunability in both bandwidth and frequency without affecting the Q is achieved for the first time. The design is patent-pending and we strongly believe that this represents a very important step towards the goal of remotely controlled filters for base stations.

60MHz DR Filter for both PCS and UMTS in the same Housing

The new tunable filter technology is used here to build full band (60 MHz) 9 pole dielectric resonator (DR) filters tuned at two different ranges separated by 200 MHz, PCS band (1930-1990 MHz) and UMTS band (2110-2170 MHz). All the measurements are taken in the same housing and the same resonators. The double conical resonators when put in proximity, provide the required strong couplings for the full band filter. The gap between the two conical parts that make the resonator, regulates the frequency over a very wide range without affecting the quality factor and helps provide a safe spurious free band. The fine tuning of the frequency is achieved with metal tuning plugs. Two different dielectric constants are used epsivr=35 and epsivr=45. In both cases, a typical 0.4 dB insertion loss is achievable for the 9 pole filter. An optimization of the design can push it very well near 0.3 dB for Er=35 or even lower. The design is patent pending and to our knowledge this full band DR filter tuned over such a wide range is presented for the first time.