All Filters

This application note describes the use of CST MICROWAVE STUDIO® in optimising the geometry of a free standing nested annular slot type Frequency Selective Surface (FSS). An isolation of better than 20 dB between the 316.5-325.5 GHz and 349.5-358.5 frequency bands was achieved in both the TE and TM planes for a 45 degree incident plane wave, while the insertion loss was below 1 dB. Read full article..

Metallic and dielectric cavity resonator filters continue to play an important role in the wireless infrastructure market. Particularly due to an increasing need co-site and co-locate several old and new standards performance requirements are getting more stringent. This is especially true for filter guard band gaps. One of the contributors to the filter bandwidth margin is the temperature drift allowance. This allowance is to allow for the filter response change due to (i) material thermal expansion/contraction, and (ii) change in the dielectric constant. A very useful technique has previously been developed to estimate the coaxial resonator temperature drift. This technique has extensively been verified in practice. However, its main limitation is that it relies on closed-form mathematical expressions, thus being applicable only to the canonical structures. In this paper we first reproduce in CST MICROWAVE STUDIO® the expected temperature drift results for commonly-used filter resonators. We then go on to show that this new methodology can be applied to structures of arbitrary shape, with an arbitrary number of elements, and with arbitrary material composition. Finally, we consider temperature drift for structures where dielectrics as well as metals change their properties at different operating temperatures. Read full article..

The Bragg Reflector implemented in the coaxial technology is an example for setting up simulations of periodic structures. The simulation is performed with CST MICROWAVE STUDIO® and compared to measurements. Read full article..

The CST EM STUDIO™ Thermal Solver has been applied to simulate the temperature distribution of a dual-mode filter. The current density distribution inside the lossy conductive metals is precomputed by CST MICROWAVE STUDIO® acting as the thermal source. Read full article..

Tuning of a coupled-resonator filter is performed in this article by using the group delay response of the input reflection coefficient of sequentially tuned resonators containing all the information necessary to design and tune filters. To achieve high out-of-band rejection losses a single transmission zero is introduced producing a pair of finite frequency poles. CST MICROWAVE STUDIO® is used to optimize and/or tune the bandpass filter resonse in a complete model by applying the new, fast MOR-Frequency Domain Solver. To speed-up the tuning process the entire model is split up into several sections and recombined in CST DESIGN STUDIO™ to get the overall filter response. Read full article..

This structure for mobile communication in LTCC technology combines a diplexer for the GSM and DCS frequency bands with a low pass filter for each band. Read full article..

This waveguide filter has been simulated with CST MICROWAVE STUDIO® general purpose frequency domain solver applying a tetrahedral mesh. Read full article..

The dichroic filter is an example for setting up simulations of frequency selective surfaces. The simulation is performed with CST MICROWAVE STUDIO® and compared to measurements. Read full article..

New, compact configurations for RF/microwave bandstop and lowpasss filters are presented. Compact footprints are achieved by folding the transmission lines in a microstrip platform. The effect of mutual coupling between the transmission lines, curved line sections, interconnecting lengths of the sections are taken into account to obtain the network parameters for the folded line filters. The folded line filters have practical dimensions for a wide range of electrical specifications, making physical implementation realizable. The filter designs have been validated by using full wave 3D EM simulation using CST MICROWAVE STUDIO®, as well as by comparison with the measurements. The new designs presented should prove useful for a host of embedded passive and RFIC applications in the 1-10 GHz range. Read full article..

The example design is a classic hairpin filter with a bandwidth of 3.6 to 4.3 GHz. The hairpin filter was designed for a return loss better than -20dB across the band. CST DESIGN STUDIO™ was used to design and tune the filter, the resulting layout was then verfied with the 3D- EM simulation software CST MICROWAVE STUDIO®. Read full article..

Shown is the discretised model of a dielectric two circuit filter with coaxial input and output couplers. Read full article..

The dual mode filter was developed, measured, and simulated by ESA (European Space Agency). Read full article..