Jing Ai

Miniaturized Quint-Band Bandpass Filter Based on Multi-Mode Resonator and

Based on multi-mode resonator (MMR) and λ/4 resonators, a miniaturized microstrip quint-band bandpass filter (BPF) with mixed electric and magnetic coupling (MEMC) has been presented. The proposed MMR is employed to generate the 1st, 2nd, and 5th passbands, while the 3rd and 4th ones of close band proximity are achieved by using four coupled λ/4 uniform impedance resonators (UIRs). Due to MEMC cancelling effect, virtual grounds in feed lines, and source-load cross coupling, multiple transmission zeros (TZs) can be yielded to obtain sharp passband roll-off skirts. To verify the validity of the design approach, a quint-band BPF centering at 2.1, 3.0, 4.0, 4.7, and 7.2 GHz (denoted as f1, f2, f3, f4, and f5) with respective 3 dB fractional bandwidths of 13.7%, 5.6%, 10.5%, 5.1%, and 2.9% has been designed and fabricated, whose measured results show good consistence with the predicted frequency responses.

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Based on the coupled-line stub-loaded shorted stepped-impedance resonator (CLSLSSIR), a compact microstrip tri-band band-stop filter (TB-BSF) with controllable frequencies, stopband attenuations (SAs), and sharp transition band roll-off skirts has been presented. The proposed CLSLSSIR exhibits multimode resonant behavior and is employed to achieve tri-stopband application by applying the virtual ground effect at the attaching position. Due to the infinite input impedance effect of CLSLSSIR, as well as the resonance of

Resonators With Mixed Electric and Magnetic Coupling

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Miniaturized Frequency Controllable Band-Stop Filter Using Coupled-Line Stub-Loaded Shorted SIR for Tri-Band Application

-type network combined with two loaded CLSLSSIRs and transmission line, multiple transmission poles can be yielded to obtain high selectivity of transition band. Finally, an example TB-BSF operating at 1.57, 2.4, and 3.5 GHz with respective SAs of 18, 26.5, and 33.2 dB has been designed and fabricated.

Miniaturized quad-band bandstop filter with controllable frequencies using multiple-mode resonator

The operating mechanism of the quad-band band stop filter (QB-BSF) with multiple-mode resonator (MMR) is introduced in this paper. Based on the design procedure, the operating stopband frequency locations of the proposed QB-BSF can be conveniently controlled. Also, the BSF features compact size and sharp roll-off skirts for transition bands. As an example, a QB-BSF centered at 1.23/1.8/2.4/3.5GHz with respective rejection levels of 22.5/47/52.1/23.7 dB has been designed.

A novel narrowband filter with cross-coupling used for system-in-package applications

A novel narrowband filter with cross-coupling is presented. By taking advantage of the structure of multilayered substrates, two substrate integrated circular cavities (SICCs) are stacked, and cross-coupling is realized between the two resonators by different slots in the middle layer. Because of the cross-coupling structure, two transmission zeros (TZs) are introduced in the out-of-band region, allowing the frequency selectivity to be improved. The simulated insertion loss at the central frequency of 33 GHz is approximately 3 dB and the 3-dB bandwidth is 0.4 GHz. The structure is simple to fabricate and practical for use in system-in-packaging applications.

A novel dual-polarized antenna with low profile and high port isolation

A novel dual-polarized antenna with low profile and high port isolation is proposed in this paper. The proposed antenna consists of two dipoles perpendicular with each other. One dipole is composed of a pair of trapezoidal patches with four triangular parasitic patches, which is the same as the other one. Each trapezoidal patch has two rectangular slots. Both of the dipoles are printed on the upper and bottom sides of the substrate, respectively. Simulated results show that the proposed antenna is able to achieve 47% impendence bandwidth (VSWR<2) over the frequency band of 2.34GHz to 3.78GHz. More importantly, the simulated port isolation is better than 62.3dB across the whole impendence bandwidth. The proposed antenna achieves good performance such as low profile, wide bandwidth with very high isolation, and stable radiation pattern.

A COMPACT WIDE BANDPASS FILTER WITH GOOD SELECTIVELY

A compact Ku-band bandpass filter (BPF) with wide passband, compact size and high selectively is presented. The presented BPF is composed of two quarter-wavelength resonators and a dual-mode resonator, resulting in a compact circuit size. The transmission zeros (TZs) located at the lower and upper stopband are achieved by the mixed electromagnetic (EM) coupling and dual-mode resonator, respectively, resulting in a high frequency selectively. The measured results show minimum in-band insertion loss, fractional bandwidth and variation of group delay to be 0.9 dB, 36.2% and 0.12 ns, respectively. Also, the stopband suppression is greater than 28 dB from 5 to 10.3 GHz and 30 dB from 19.5 to 29.5 GHz. The effective circuit size of the filter is 8.43× 2.28 mm2 (0.63λg × 0.17λg , where λg is the guide wavelength of 15.1 GHz).

Dual high-selectivity band-notched UWB monopole antenna using simple dual-mode resonator and high-impedance lines

A new planar microstrip-fed monopole ultra-wideband (UWB) antenna with dual notched bands has been presented. By employing a simple dual-mode resonator with two symmetrical outer high-impedance lines beside the microstrip feed line of the proposed UWB antenna, two controllable rejection bands with high-frequency selectivity are created. The parametric studies of the proposed structure are explored for the dual band-notched operating mechanism. Finally, the experimental results, including return losses, radiation patterns, and peak gains are shown, declaring that the proposed antenna has good impedance matching performance and radiation pattern properties.

Split-type quad-band bandpass filter with quarter-wavelength resonators

In this paper, a split-type sharp rejection microstrip quad-band bandpass filter (BPF) with X/4 resonators has been presented. Two split-type dual-band BPFs are studied and combined to form quad-band responses. The quadruplet coupling topology is introduced to generate source-load coupling, resulting in one pair of transmission zeros at each side of all the four passbands. Eventually, a quad-band BPF centered at 2.1, 2.4, 3.9 and 4.5 GHz with respectively fractional bandwidths of 8.5%, 3.4%, 5.5% and 4.9% has been designed and implemented, whose measured results provide a good verification for the simulated ones.