Dr. Senad Bulja, PhD, FIET, SMIEEE https://drbulja.com Mon, 19 Aug 2024 06:14:12 +0000 en-US hourly 1 Split-distributed resonators and filters https://drbulja.com/split-distributed-resonators-and-filters-317/ https://drbulja.com/split-distributed-resonators-and-filters-317/#respond Mon, 06 Feb 2023 07:57:05 +0000 https://drbulja.com/?p=317 We have recently introduced a new class of cavity resonators and filters, termed distributed resonators [1] and [2]. The distributed resonator allows a major reduction in the resonator profile while maintaining an excellent electrical performance. In [1], an individual distributed resonator consists of a number of low-profile resonant posts arranged in a grid, where the resonant posts on the vertical and horizontal axes of the grid mainly couple to their immediate neighbors. The substantial reduction in the filter profile, comes – to a degree – at the price of the footprint, mainly due to the fact that the individual distributed resonator consists of a number of resonant posts. 

In this paper, the concept of [1] and [2] is further generalized by realizing the individual resonant element in a distributed form. The new resonator is termed split-distributed resonator since the individual resonant post is effectively split in order to better exploit mutual coupling. Due to their split configuration, the individual distributed resonant posts no longer strongly couple only to their neighbors on the vertical and horizontal axes, but to their diagonal elements as well. This has a profound effect on the reduction of resonator footprint, while maintaining the low resonator profile and excellent electrical performance.  As a practical demonstrator, a 5-pole is designed and fabricated, and its performance tested. The filter is made to operate at a frequency of 1.8 GHz, with an absolute bandwidth of 40 MHz. Each resonator of the proposed filter consists of 9 split-distributed resonant elements, placed in close proximity. The chamber size of each resonator is 30 mm x 30 mm x 7 mm, with an unloaded quality factor of over 1700.  The measured insertion loss of the filter is 0.94 dB, which is in excellent agreement with the theoretically predicted value of 0.76 dB. 

Fig. 1 Fabricated 5-pole split-distributed filter with individual resonators (left) and Measured and simulated S-parameters of 5-pole split-distributed filter – dashed line: computed; solid line: measured.
Fig. 1 Fabricated 5-pole split-distributed filter with individual resonators (left) and Measured and simulated S-parameters of 5-pole split-distributed filter – dashed line: computed; solid line: measured.

 

[1] S. Bulja and M. Gimersky, “Low-Profile Distributed Cavity Resonators and Filters,” IEEE Trans. Microw. Theory Techn., vol. 65 issue 10, pp. 3769-3779, 2017.

[2] S. Bulja, E. Doumanis and D. Kozlov, “Concentric distributed resonators and filters”, in Radio and Wireless Symposium (RWS), Anaheim, CA, USA, 2018, pp.267-269.

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]]> https://drbulja.com/split-distributed-resonators-and-filters-317/feed/ 0 PCB Distributed Filters https://drbulja.com/pcb-distributed-filters-309/ https://drbulja.com/pcb-distributed-filters-309/#respond Fri, 03 Feb 2023 06:44:50 +0000 https://drbulja.com/?p=309 We have recently introduced a new class of cavity resonators and filters, termed distributed resonators [1] and [2].  The distributed resonator allows a major reduction in the resonator profile while maintaining an excellent electrical performance. In [1], an individual distributed resonator consists of a number of low-profile resonant posts arranged in a grid, where the resonant posts on the vertical and horizontal axes of the grid mainly couple to their immediate neighbors. The substantial reduction in the filter profile, comes – to a degree – at the price of the footprint, mainly due to the fact that the individual distributed resonator consists of a number of resonant posts. In our previous contribution of [2], the concept of [1] is somewhat further generalized, where it was suggested that a resonant element of [1] can itself be made in a distributed form. In both [1] and [2], the resonators and filters are made to operate in the air.

In this paper, a new family of ceramic resonators and filters is introduced. The proposed resonators are enabled by the integration of distributed resonators into standard Printed Circuit Board (PCB) substrates. This integration caters for not only a tremendous reduction in the resonator profile, but it also enables utilization of the unused PCB real estate. As an example of the feasibility of the proposed idea, a 3-pole filter based on 3-by-3 distributed resonant elements was designed and fabricated, Fig. 1. The filter was made to operate at a frequency of 1.12 GHz with a bandwidth of 20 MHz. The substrate used for this filer has the dielectric permittivity of 12.85 and a loss tangent of 0.0019. The measured results show a good agreement with simulations, Fig.1. 

Fig. 1 Fabricated 3-pole PCB distributed filter (left) and Measured and simulated S-parameters of 3-pole PCB distributed filter the left – dashed line: computed; solid line: measured.
Fig. 1 Fabricated 3-pole PCB distributed filter (left) and Measured and simulated S-parameters of 3-pole PCB distributed filter the left – dashed line: computed; solid line: measured.
  1. S. Bulja and M. Gimersky, “Low-Profile Distributed Cavity Resonators and Filters,” IEEE Trans. Microw. Theory Techn., vol. 65 issue 10, pp. 3769-3779, 2017.
  2. S. Bulja and D. Kozlov, “Split-distributed resonators and filters”, Radio and Wireless Symposium, Orlando, US, January 2019. 

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