1,720,996 research outputs found
Microwave components realized by additive manufacturing techniques
No full textThis paper presents an overview of the use of additive manufacturing (AM) technologies for the implementation of microwave components. Two major technological solutions, based on the AM of plastic materials, are discussed: in the former case, the AM plastic is used as a dielectric material that constitutes the component. Conversely, in the latter case, the plastic material is a mere support of the metallization, thus avoiding the contact of the AM plastic with the electromagnetic field and reducing losses. Several examples are illustrated and discussed, to highlight benefits and limitations of AM techniques in the current scenario of microwave applications
Wideband Bandpass TM Cavity Filters With Wide Spurious Free Band
No full textRecently, the spurious self-suppression method has been introduced and applied to the bandpass TM cavity filters to improve their stopband performance. However, this method has the limitation of being applicable only to TM narrow-band filters. This paper shows how to overcome this limitation. In particular, it shows how to increase the bandwidth and improve the stopband performance by removing the spurious resonance of the coupling irises due to TE10 mode. The conventional rectangular iris is replaced by a new bent c-shaped iris. In this way, the resonance of the iris TE10 mode can be shifted to lower frequencies (below the cut-off), improving the stopband performance of the filter. Moreover, this new iris shape provides large couplings that allow wide passbands, and strong excitation of the spurious resonant modes that allows for an efficient implementation of the spurious self-suppression method. Furthermore, double slot iris has been used to connect the two central cavities to increase the central coupling of the filter. Design examples of 4th order and 6th order TM cavity filters with wide spurious free range up to 18 GHz having fractional bandwidth (FBW) of 5% and 4%, respectively, are presented. Finally, the 6th order TM cavity filter has been manufactured and measured. Good agreement has been achieved between simulated and measured frequency responses
A New Resonant Coupling Structure for Inline Waveguide Filters with Transmission Zeros
No full textIn this work a novel resonant coupling structure in rectangular waveguide is introduced. The proposed structure allows the introduction of transmission zeros in the response of inline filters. The main advantage with respect to the resonant couplings usually adopted (i.e., resonant posts) is that the new structure allows the placing of transmission zeros very close to the passband. Moreover, it does not require any extra space as instead does the stopband singlet recently introduced for the same purpose. An equivalent circuit of the novel coupling structure is proposed, suitable for the use in the synthesis of filters with frequency-dependent couplings. Dimensioning charts are then introduced, to make it easy the initial assignment of the physical dimensions of the structure so that the extracted equivalent parameters have the assigned values. Finally, an example of use of the novel coupling structure in a 6-2 waveguide filter in Ka band is presented
Stereolithography Additive Manufacturing of Overmoded Spherical Filters
No full textIn this paper, we provide an overview of the stere-olithography (SLA) manufacturing process applied to the design of microwave filters. For that purpose, a spherical cavity that operates with the higher order mode TE101 has been used in order to design filters oriented for additive manufacturing. The characteristics of such mode (high Q-factor and size) makes it an interesting choice for filters manufactured with 3-D printers. For validation purposes, two doublet prototypes with different configurations and mechanical structures have been manufactured with an SLA 3-D printer, metallized, and measured. Results show various discrepancies between the two prototypes: with measurements matching fairly well with the simulations for one prototype, while a certain frequency shift is present for the other one
3-D-Printed Dual-Mode Filter Using an Ellipsoidal Cavity With Asymmetric Responses
No full textA new structure based on an ellipsoidal cavity that operates with the fundamental mode and its degenerate in a transverse routing scheme is presented in this paper. This configuration yields asymmetric filtering functions with two poles and one transmission zero, whose position can be easily controlled by the rotation of the input and output. For validation purposes, a two-pole filter has been designed and manufactured using 3-D printing techniques. Measured results demonstrate the feasibility of the proposed filter with good agreement between simulation and measurement
A New Termination Condition for the Application of the TLM Method to Discontinuity Problems in Closed Homogeneous Waveguide
No full textNovel Triple-mode Dielectric Cavity Filter Using Grooved Dielectric Resonator
No full textIn this paper, the TE01δ mode and the two degenerate HEH11 modes of traditional high dielectric cylinder resonator are gathered in frequency by grooving the puck in four directions, resulting in a hybrid triple mode resonator with high Q factor. A compact and low loss one-cavity triple-mode filter is then designed with such a resonator. Good features like low loss, sharp rejection and compact size are demonstrated by the measured results
Compact SIW filters with transmission zeros: A review and current trends
No full textThis paper presents a review of the recent advances in the field of substrate integrated waveguide (SIW) filters, with particular emphasis on the techniques adopted to increase the out-of-band rejection of the filters and on the miniaturization strategies. After an overview of classical approaches to introduce transmission zeros in SIW filters, a number of recently introduced techniques are presented. In particular, the use of specially implemented extracted-poles topologies and of pre-filters is described, discussed, and compared. For each of these techniques, numerical and experimental results are reported for validation
Spurious suppression through the control of their couplings: application to TM cavity filters
No full textIn this paper, a new approach for improving filter spurious free band is proposed. The main idea is to control the coupling coefficients of the spurious resonances in order to force them to cancel each other. The required coupling levels can be estimated by using an equivalent circuit. It is observed that, in contrast with what is commonly done, it is not convenient decreasing all couplings to the spurious resonances. The only coupling to be minimized is the central one, all other should instead be maximized.
This procedure can be used for suppressing spurious resonances generated by higher order modes. This method has been here applied to TM cavity filters. As shown in the paper, it is in general applicable to even order filter only. In this paper, a two-pole TM cavity filter centered at 9 GHz with a 3 dB FBW of 1.45% has been designed and manufactured. By applying this technique, the spurious free band has been increased from 12.4 GHz of the initial design to 19.7 GHz. Measured results show the feasibility of the proposed approach
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