Sharp Skirt Characteristics Research Articles

A Compact, Hybrid SIW Filter With Controllable Transmission Zeros and High Selectivity

A novel, highly selective, and compact filter with controllable transmission zeros (TZs) is proposed in this brief. The hybrid structure of the proposed filter is based on the substrate integrated waveguide (SIW) and microstrip line resonators. The negative magnetic coupling was introduced through a full-wavelength microstrip line resonator, and the additional TZ was added by the cross-coupling of indirectly connected resonators in the traditional box-like topology. Consequently, high selectivity is achieved with TZs located at both sides of the passband. The independent control of the left and right TZs can be realized by controlling the cross-coupling and external coupling. The proposed work achieves good performance, including sharp skirt characteristics, compact size, and low loss. As a validation of the concept and performance, a filter prototype designed following the procedure is fabricated and measured.

인공전송선로를 이용한 이중모드 링-공진기 대역통과 여파기

Abstract This paper presents dual-mode ring-resonator bandpass filter using LUC of artificial-transmission-lines. The conventional ring-reso-nator bandpass filter has limitation in miniaturization because the conventional ring-resonator is based on a one wavelength operation, and problem due to undesire harmonics. The ring-resonator bandpass filter is miniaturized and show higher order mode rejection by configuring a ring-resonator with LUC of artificial-transmission-lines. The two-stage bandpass filter is designed and fabricated with a ring-resonator and input/output interdigital coupled line. A fabricated filter shows dual-mode, rejection of whole ultra wide band, sharp skirt characteristics and has ring area reduced by 60 % compared to the conventional ring-resonator bandpass filter.Key words: Artificial-Transmission-Line, LUC, Dual-Mode, Ring-Resonator, Higher Order Mode Rejection, Miniaturization, Ultra Wide BanddeC$2016fghi8fjfkeC7@l(mnop520150461)#A8' eCqrs.t i8fjBIT#uvRf(Department of BIT Medical & Electrical and Electronics Engineering, Kangwon National University)

Analysis of Novel Approach to Design of Ultra-wide Stopband Microstrip Low-Pass Filter Using Modified U-Shaped Resonator

A novel microstrip low-pass filter is presented to achieve an ultra-wide stopband with 11 harmonic suppression and very sharp skirt characteristics. The filter is composed of a modified U-shaped resonator (which creates two fully adjustable transmission zeroes), a T-shaped resonator (which determines a cut-off frequency), and four radial stubs (which provide a wider stopband). The operating mechanism of the filter is investigated based on a proposed equivalent-circuit model, and the role of each section of the proposed filter in creating null points is theoretically discussed in detail. The presented filter with 3 dB cut-off frequency () has been fabricated and measured. Results show that a relative stopband bandwidth of 164% (referred to as a 22 dB suppression) is obtained while achieving a high figure-of-merit of 15,221.

Design of Microstrip LPF with Sharp Cut-off Frequency and Wide Stopband

AbstractA novel lowpass filter with wide stopband and sharp skirt characteristics is proposed. To obtain the applicable lowpass filter, several cells of coupled T-shaped resonator, U-shape and dumbbell-shaped resonators are connected in series. The proposed filter has low insertion loss, high return loss in the passband and wide stopband. The transition band is from 3.18 to 3.29 GHz with −3 and −20 dB, respectively. Results of the fabricated filter exhibit a roll-off and relative stopband bandwidth of 217 and 137%, respectively. Measurement and simulation results show good agreement.

Development of IMD3 Measurement System Around 5 GHz Using HTS Notch Filters

We developed a third intermodulation distortion (IMD3) measurement system around 5 GHz in order to realize superconducting transmit filters in a mobile communication system. We added a high temperature superconducting (HTS) notch filter to the simple IMD measurement system and then focused on reducing the system noise levels. We designed and fabricated the HTS notch filter composed of three-pole hair-pin resonators with high attenuation and sharp skirt characteristics. The IMD characteristics measured using the system were reduced by 49.7 dBm by using the HTS notch filter.

Design of Sharp Roll-Off Lowpass Filter With Ultra Wide Stopband

A novel microstrip lowpass filter is proposed to achieve an ultra wide stopband with 12th harmonic suppression and extremely sharp skirt characteristics. The transition band is from 1.26 to 1.37 GHz with -3 and -20 dB, respectively. The operating mechanism of the filter is investigated based on proposed equivalent-circuit model, and the role of each section in creating null points is theoretically discussed. An overall good agreement between measured and simulated results is observed.

Design of Microstrip Bandpass Filters Using SIRs with Even-Mode Harmonics Suppression for Cellular Systems

The design of microstrip bandpass filters using stepped-impedance resonators (SIRs) is examined. The passband center frequency for the WCDMA-FDD (uplink band) Japanese cellular system is 1950 MHz with a 60-MHz bandwidth. The SIR physical characteristic can be designed using a SIR characteristic chart based on second harmonic suppression. In our filter design, passband design charts were obtained through the design procedure. Tchebycheff and maximally flat bandpass filters of any bandwidth and any number of steps can be designed using these passband design charts. In addition, sharp skirt characteristics in the passband can be realized by having two transmission zeros at both adjacent frequency bands by using open-ended quarter-wavelength stubs at input and output ports. A new even-mode harmonics suppression technique is proposed to enable a wide rejection band having a high suppression level. The unloaded quality factor of the resonator used in the proposed filters is greater than 240.

Elliptic-function lowpass filter with sharp cutoff frequency using slit-loaded tapered compact microstrip resonator cell

A novel slit-loaded tapered compact microstrip resonator cell to design a class of elliptic function compact lowpass filter with sharp skirt characteristics is proposed. Several cells are connected in series form to obtain an excellent lowpass filter. The bandwidth is enhanced and the size is reduced compared to conventional tapered resonators. The results of filter simulation with an EM-simulator and measurement show accurate attenuation at cutoff frequency. The proposed filters have compact and simple structures, small sizes, high selectivity, wide stopband, low insertion loss, etc; all these features are the requirements of wireless communication circuits. Measurement results show good agreement with the simulation.

A Study on Compact Wide Bandpass Filter Using Inter-Digital Resonator

A new type of the wide-band BPF made up of an inter-digital resonator and parallel-coupled lines was proposed. The bandwidth of the inter-digital resonator becomes wider by increasing the number of fingers. The design of the parallel-coupled line was performed by optimazing the structural parameters so that the bandwidth is the same as that of the inter-digital resonator. The measured results of the combination of above elements for the BPF agreed well with the simulated ones such that the insertion loss is less than 0.67dB and that the sharp skirt characteristics are realized by attenuation poles near the edges of the passband.

Compact Low-Pass Filter with Sharp Skirt Characteristics and Broad Stopband

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

Cryogenic receiver front-end with sharp skirt characteristics

This paper presents an experimental cryogenic receiver front-end (CRFE) with sharp skirtcharacteristics for mobile base stations. The CRFE comprises a high-temperaturesuperconducting filter, a cryogenic low-noise amplifier, and a highly reliable cryostat that isvery compact. The major characteristics of the proposed CRFE measured at 70 K area centre frequency of 1.95 GHz, passband width of 20 MHz, sharp selectivity of20 dB/100 kHz, 1.4 dB ripple, 31.3 dB average passband gain, and average passband equivalent noisetemperature of 47.9 K. The CRFE weighs 19 kg and occupies 35 l. Random failure of thecryostat is also evaluated by a continuous operation test using four identical onessimultaneously. The cryostat used in the CRFE has a high reliability level of over five yearsof continuous maintenance-free operation.

High- Tc superconducting tunable filter with steep attenuation

We developed a compact RF receiver front-end subsystem using a high- T c superconducting sharp-skirt band-pass filter with a center frequency tuning function. The subsystem had two pairs of the tunable filter and an LNA on board. A 23-pole hairpin-type 2-GHz microstrip-line filter was fabricated with YBa 2Cu 3O y thin films deposited on a 35-mm-wide and 70-mm-long sapphire substrate. Attenuation characteristics were more than 40 dB at 1 MHz, apart from both the lower and the higher pass-band edges. For center frequency tuning, a 1-mm-thick dielectric sapphire plate was stacked on the filter, and the filtering characteristics were tuned by moving the plate using a piezoelectric bending actuator. The range of the center frequency modulation was more than 10 MHz with no significant degradation of the low-loss and sharp-skirt characteristics.

2 GHz tunable superconducting band-pass filter using a piezoelectric bender

We have developed a 2 GHz tunable superconducting band-pass filter using a piezoelectric bending actuator. The filter is a 12-pole microstrip line structure on 50 mm diameter LaAlO 3 substrate and has low loss and sharp skirt characteristics. The center frequency was 1.94 GHz and the attenuation characteristics were 30 dB at 1 and 3 MHz apart from the lower and higher band-edge, respectively. A sapphire (Al 2O 3) plate was stacked on the filter with an air gap and the gap thickness was controlled electrically from the outside of a refrigerator using a piezoelectric bending actuator. The center frequency of the filter could be adjusted within 11 MHz in such a manner that the low loss and sharp skirt characteristics were not degraded.

Frequency responses of 14 GHz hairpin type superconducting bandpass filter

For the performance enhancement of communication systems, high quality filters are required. Also a size minimization of the filter is required for the integration of device in the limited area. Hairpin type filters have been designed with the center frequency of 14 GHz for the size reduction. Superconducting YBCO thin films have been grown on MgO substrates by pulsed laser deposition with a Nd:YAG laser. YBCO thin films were patterned by a conventional wet-etching process. The transition temperatures of these films have shown to be in the range of 86–89 K. The film thickness was measured to be about 500 nm. With the simulation results, the frequency responses showed low insertion loss and sharp skirt characteristics. The frequency response of HTS 14 GHz filter was measured at 77 K and compared with the simulation result.