Uros Jankovic

Bio: Uros Jankovic is an academic researcher from University of Westminster. The author has contributed to research in topics: Band-pass filter & Waveguide filter. The author has an hindex of 3, co-authored 14 publications receiving 38 citations.

Ultra Compact Inline $E$ -Plane Waveguide Bandpass Filters Using Cross Coupling

Abstract: This paper presents novel ultracompact waveguide bandpass filters that exhibit pseudoelliptic responses with the ability to place transmission zeros on both sides of the passband to form sharp rolloffs. The filters contain $E$ -plane extracted pole sections (EPSs) cascaded with cross-coupled filtering blocks. Compactness is achieved by the use of evanescent mode sections and closer arranged resonators modified to shrink in size. The filters containing nonresonating nodes are designed by means of the generalized coupling coefficients’ extraction procedure for the cross-coupled filtering blocks and EPSs. We illustrate the performance of the proposed structures through the design examples of third- and fourth-order filters with center frequencies of 9.2 and 10 GHz, respectively. The sizes of the proposed structures suitable for fabricating using the low-cost ${E}$ -plane waveguide technology are 38% smaller than ones of the ${E}$ -plane extracted pole filter of the same order.

Hybrid manufactured waveguide resonators and filters for mm-wave applications

Abstract: Additive and hybrid manufactured waveguide resonators and bandpass filters for mm-wave applications are presented. A Ka band 3D printed waveguide resonator with inductive windows and 28 GHz 5G band hybrid manufactured waveguide resonator and bandpass filter are designed. Hybrid manufacturing combines 3D polymer printing and conventional metal processing technologies. In order to illustrate the accuracy of the design, a 3D printed waveguide transmission line and resonator with the resonant frequency of 33 GHz are fabricated and tested.

Ultra compact pseudo-elliptic inline waveguide bandpass filters using bypass coupling

Abstract: This paper presents an ultra compact waveguide bandpass filter that exhibits a pseudo-elliptic response. The transmission zero created in the upper stopband to form a rapid roll off is produced through a bypass coupling with higher order modes. A 3rd order filter is designed at the centre frequency of 9.4 GHz with a 5.3% fractional bandwidth. The proposed structure's size is 38% smaller than one of a 3rd order E-plane extracted pole filter with comparable response. Additionally, this configuration allows larger span of different bandwidths. The filter has been fabricated and tested using E-plane waveguide technology, which has benefits of being inexpensive and having mass producible capabilities. Measurements of such a fabricated filter validate the simulated results.

Compact E-plane varactor -tuned bandpass filters

Abstract: This paper presents electromagnetic simulation of a varactor-tuned E-plane waveguide band-pass filter. Silicon varactor diodes which can operate through X band are placed between gaps in the centre fins of an E-plane extracted pole section to provide tuneability for the filter structures. The simulation of the filter was carried out by CST Microwave Studio with the diodes being modelled by its Spice model in CST Design Studio. Tuning range of 280 MHz is achieved.

Ultra compact E-plane waveguide multiplexers

Abstract: This paper present ultra compact diplexers and triplexers based on ultra compact E-plane waveguide filters. The ultra compact filters have significantly better attenuation and selectivity at both upper and lower stop bands compared to that of conventional E-plane filters. This allows channels to be placed much closer to one another. The filters retain ease of manufacturing of typical E-plane filters. Simulation and experimental verification of one such filter is given and simulation of a diplexer and triplexers based on such filters are demonstrated.

3D Printing of Microwave and Millimeter-Wave Filters: Additive Manufacturing Technologies Applied in the Development of High-Performance Filters with Novel Topologies

Abstract: Three-dimensional (3D) printing, additive manufacturing (AM), digital manufacturing, and free-form fabrication are some of the synonymous expressions commonly used to identify the new class of processes through which objects are built by selectively adding material, usually layer by layer, instead of subtracting material, as in conventional machining techniques like chemical etching, laser-cutting, milling, and electroerosion [1].

Lightweight Perforated Waveguide Structure Realized by 3-D Printing for RF Applications

Abstract: Waveguide structures are criticized for their bulky geometry and heavy weight in practical applications. Therefore, it is necessary to investigate the weight-reduction technique of the waveguide structures, while maintaining their electrical properties and mechanical fabricability. In this paper, a waveguide perforation technique for lightweight purpose is proposed, and an X-band pyramidal horn antenna that employs this technique is developed and tested. To ease the manufacturing process of the 3-D thin-wall structure, a 3-D metal-direct-printing technology is utilized to fabricate the perforated horn. Meanwhile, a full-metal horn without any perforation and a horn printed in dielectric material but coated with metal are also included to compare with the proposed one. Experimental results show that around two-thirds of the total weight can be reduced. Other measured results in terms of electrical performance are in excellent agreement with the full-metal ones, validating the feasibility of the design and fabrication approach. The novelty of this paper realized by the 3-D printing technique is a promising strategy to inspire lightweight structure designs for radio frequency applications.

Emerging Trends in Techniques and Technology as Applied to Filter Design

Abstract: In the last decade, the filter community has innovated both design techniques and the technology used for practical implementation. In design, the philosophy has become “if you can't avoid it, use it”, a very practical engineering approach. Modes previously deemed spurious are intentionally used to create in-line networks incorporating real or imaginary transmission zeros and also reduce the number of components and thus further miniaturize; spurious responses are re-routed to increase the passband width or stopband width, frequency variation in couplings is used to create complex transfer functions, with all of these developments using what was previously avoided. Clever implementations of baluns into passive and active networks is resulting in a new generation of noise-immune filters for 5G and beyond. Finally, the use of a diakoptic approach to synthesis has appeared an evolving approach in which small blocks (“singlets”, “doublets”, etc.) are cascaded to implement larger networks, (reducing the need for very complex synthesis), with this new approach promising a large impact on the implementation of practical structures. Filter technology has migrated towards “observe it and then adapt it”, pragmatically repurposing tools not specifically originally intended for the applications. Combinations of surface wave and bulk wave resonators with L-C networks are improving the loss characteristics of filters in the region below 2 GHz. Lightweight alloys and other materials designed for spacecraft are being used in filters intended for space, to provide temperature stability without the use of heavy alloys such as Invar. Fully-enclosed waveguide is being replaced in some cases by planar and quasiplanar structures propagating quasi-waveguide modes. This is generically referred to as SIW (Substrate Integrated Waveguide). Active filters trade noise figure for insertion loss but perhaps will offer advantage in terms of size and chip-level implementation. Finally, the era of reconfiguration might be approaching, as the basic networks are evolving, perhaps lacking only the appearance of lower-loss, higher-IP solid-state tuning elements.

A Novel Compact $E$ -Plane Waveguide Filter With Multiple Transmission Zeroes

Abstract: This paper presents a novel compact $E$ -plane waveguide filter using multiple resonators, which lead to multiple transmission zeroes The proposed filter is less than $015~\lambda_{ g}$ in length of a waveguide The key of the proposed method is to design the locations of transmission zeroes Four transmission zeroes, of which two are located in the upper stopband, while the other two are in the lower stopband, are produced by four resonators The couplings between the resonators and locations of the transmission zeroes are carefully analyzed and designed, which enhance the selectivity as well as the out-of-band performance Theoretical studies and experimental investigations are conducted to demonstrate the proposed design The good agreement between the simulation results and measurement results is achieved Moreover, this kind of filter can be implanted well in $E$ -plane structures

Bandpass Filters Designed by Transmission Zero Resonator Pairs With Proximity Coupling

Abstract: The concept of transmission zero resonator pair (TZRP) is used in this paper. Based on this TZRP, a new method to induce a passband is demonstrated, by which different types of bandpass filters can be designed. The proposed TZRP is structured by a pair of resonators with different resonant frequencies, which lead not only to two transmission zeroes, but also to a transmission pole between them. Passband filters can then be built by designing the proximity coupling between the TZRPs, as the TZRP works as a basic resonant element. The passband of these filters can be flexibly controlled by the resonators of TZRPs, which determine the locations of the transmission zeroes and poles. By carefully allocating the transmission zeroes, high selectivity and large out-of-band rejection can be realized. This design method is applied to design filters in two different transmission media, namely, microstrip line and rectangular waveguide. Simulated and measured results demonstrate the effectiveness of this new approach of bandpass filter design. The designed filters have the properties of small size, easy fabrication, low cost, and low loss.