Suspended Substrate Stripline Research Articles

Study and Design of A Dual Mode Resonant Band-Pass Filter Suspended Substrate Stripline for 5G Communications

Study and Design of A Dual Mode Resonant Band-Pass Filter Suspended Substrate Stripline for 5G Communications

Super‐wideband cascaded bandpass filter using suspended substrate stripline technology

AbstractThis paper presents a wideband cascaded bandpass filter with a fractional bandwidth of 160% centered at 10 GHz using suspended substrate stripline technology. The highpass and lowpass filters are both 11th‐order generalized Chebyshev designs with a cutoff frequency of 2 and 18 GHz, respectively, and cascaded to form a continuous 2‐18 GHz bandpass filter. Simulated and measured results of all of the filters show good agreement, and measured results of the cascaded bandpass filter shows less than 2 dB of insertion loss and greater than 10 dB of return loss over the entire passband.

Cascaded suspended substrate stripline bandpass filter

AbstractA new design of bandpass filter on a single layer implemented by using high Q suspended substrate stripline (SSS) structure is proposed. The designed filter is composed of cascaded highpass (HPF) and lowpass (LPF) filters, which forms a passband with a fractional bandwidth of 21.4% centered at 1.58 GHz and exhibits a very good selectivity through two transmission zeros. The simulated and measured results show a good agreement over the bandwidth with the in‐band insertion and return losses of 0.31 dB and 17.7 dB, respectively.

Design and characterisation of dual‐mode suspended‐substrate stripline filter

A new design technique of a dual-mode ring-resonator suspended-substrate stripline filter is reported here to achieve low passband insertion loss, high quality factor, and good spurious response. A fourth-order bandpass filter was designed and fabricated at the operational frequency of 2.07 GHz with two ring resonators packaged in a metallic cavity where each ring resonator is one wavelength long. The transmission zeros of the dual-mode filter are generated due to the phase cancellation between the two paths in a ring, thus a sharp-skirt selectivity filter response was achieved. Perturbation notch structure was implemented on each ring resonator to provide the electromagnetic coupling of two degenerate modes, thus a dual-mode response of the filter can be synthesised. Measurement results of the first dual-mode filter prototype showed a return loss and an insertion loss of better than 16.42 and 0.926 dB, respectively, while an out-of-band rejection of up to 55 dB was achieved. The novel filter design technique proved that no cross-coupling is required to obtain the transmission zeros of the filter, thus the sharp-skirt response was achievable.

Tunable narrow bandwidth of a bandpass filter combined microstrip and suspended substrate stripline

AbstractThis paper introduces a narrow bandwidth tunable filter. The filter has been tuned electronically by using varactor diodes. A set of mechanically tuning screws have been utilized to overcome the manufacturing tolerance of the filter's resonators. In contrast to most the combline filters, which depend on the cross‐coupling approach to generate the transmission poles, the proposed filter has a pair of transmission zeros located on both sides of the passband, by employing two uncoupled microstrip resonators that have been electronically tuned independently. The proposed filter bandwidth tuning range is 59–88 MHz with 3 dB fractional bandwidth 1.94–2.76 respectively. A detailed demonstration of the suggested tunable filter is introduced based on a mathematical approach.

Design of 2N-diode power-combined frequency tripler with coupled suspended striplines

A novel scheme for power-combined frequency tripler adopting 2N diodes is proposed in this work. Even mode coupled suspended substrate stripline is used to divide and recombine the input and output power. The circuits of the tripler are printed on both sides of the substrate, with N diodes on the front side and the other N diodes on the back side. The front diodes and back diodes are in anti-parallel connection, and DC biased separately to increase the bandwidth and power capacity. Three Q-band prototypes with two, four, and six diodes are fabricated and tested. The output compression powers at output frequency of 43.5 GHz for two/four/six-diode tripler are 9.2, 11, and 12 dBm, respectively. Power capacity is improved with the proposed tripler. Optimum DC bias is also discussed in this work, and it is found that it first increases with drive power, and then drops when large drive power applied because of the increased series resistance of the diode due to high junction temperature.

Classes of reconfigurable band‐reject filters realising constant absolute bandwidth in two distinct states

This study presents the synthesis and design of novel band-reject filters whose frequency characteristics can be reconfigured between two distinct states, each of which is centred at a different resonant frequency. The absolute bandwidth of the reconfigurable filters in the two distinct states is maintained constant by virtue of introducing two new resonator types which are thoroughly studied and analysed in this work. The synthesis of two prototype networks realising a common electrical specification is illustrated and each network is subsequently transformed into two types of band-reject filters comprising novel coupled-line sections. The presented circuit concepts are then validated through the simulation of a suspended-substrate stripline filter modelled utilising high frequency structure simulator (HFSS) which realises an absolute bandwidth of 200 MHz in the two distinct states centred at 1180 and 1485 MHz. The HFSS filter model is manually reconfigured between the two distinct states upon terminating stubs within each of its resonator structures as either open circuit or short circuit. The performance of the HFSS filter model shows close correspondence to the performance of the synthesised prototype network, thus demonstrating the validity of the proposed circuit principles.

P-i-n-Diode-Based Four-Channel Switched Filter Bank With Low-Power TTL-Compatible Driver

The design of a four-channel switched filter bank in the S- and C-band using p-i-n-diode switches is described. Narrowband filters (3.2%-3.5%) are designed on suspended substrate stripline. The biasing circuit allows the switches to be driven with transistor-transistor-logic-compatible voltages and minimum biasing current. The average insertion loss measured is 3.6 dB corresponding to a Q-factor of 580. Spurious responses were suppressed from dc to roughly 19 GHz.

PLANAR BANDPASS FILTER WITH 100-DB SUPPRESSION UP TO TENFOLD PASSBAND FREQUENCY

This paper proposes a miniature microwave bandpass fllter. It comprises quasi-lumped suspended substrate stripline resonators of a new type. Their common substrate consists of two contiguous dielectric layers. Every resonator in the fllter has three parallel strip conductors. Two of them are placed on the outer substrate surfaces and the rest is placed inside the substrate. The fllter of the sixth order was designed with the use of special optimization rules that are universal for all resonator fllters. The substrate of the fabricated fllter was made of RT/Duroid 5880 (r = 2:2, tan- = 0:002) with thickness of 0.127mm. It has dimensions of 12mm £ 45:5mm. The measured passband has a center frequency of 1.01GHz, 3-dB fractional bandwidth of 11%, and minimum insertion loss of 1.4dB. The 100-dB upper stopband extends up to 10.5GHz.

Generalised parallel‐coupled line and interdigital filters with unusually broad upper stop bandwidth:synthesis and design in homogeneous media

The synthesis and design of generalised parallel-coupled line and interdigital filters suitable for realisation in a homogeneous media are proposed in this study. The filters comprise novel coupled line sections whose synthesis is discussed in detail leading to the derivation of formulae to evaluate their modal-impedances. It will be shown that the proposed filters comprise asymmetrically coupled stepped-impedance resonators and are capable of realising broad upper stopbands. Filter examples are synthesised and subsequently realised in suspended-substrate stripline technology were simulated utilising High Frequency System Simulator (HFSS) show close correspondence to theoretical predictions.

SUSPENDED SUBSTRATE STRIPLINE BANDPASS FILTERS WITH SOURCE-LOAD COUPLING STRUCTURE USING LUMPED AND FULL-WAVE MIXED APPROACH

This paper presents the design of two suspended substrate stripline (SSS) bandpass fllters (BPFs), both with a source-load coupling structure embedded to create a transmission zero (TZ) near each side of the passband edges. For the flrst BPF, the physical circuit layout is proposed flrst and followed by the establishment of an equivalent LC circuit. The optimization of element values of the LC circuit using a circuit-level simulator leads to quick adjustment of the structural parameters of the physical circuit layout with the aid of a full-wave simulator. For the second BPF, the ingenious equivalent LC circuit modifled from that of the flrst one is proposed for bandwidth enhancement, which is achieved by exciting two extra loaded resonances in the passband. With the element values of the LC circuit optimized, proper reshaping the physical circuit layout from that of the flrst BPF is easily accomplished. The presented lumped and full-wave mixed approach is very e-cient in that the circuit- level simulator is used to the largest extent and the time-consuming full-wave simulator is employed only at the later stage of the design. Experiments are conducted to verify the design of the two SSS BPFs and agreements are observed between the measured and simulated data.

A Suspended-Substrate Ku-Band Symmetric Radial Power Combiner

This letter presents a novel eight-way radial power combiner that exhibits wide bandwidth and very low insertion loss. The peripheral ports of this power combiner use low loss suspended substrate stripline. A cylindrical cavity is introduced as the power combining structure to obtain high combining efficiency and high power handling capability. The proposed power combining structure successfully integrates planar transmission lines with a 3-D cavity structure to realize a wide band, low loss, and compact eight-way power combiner. Measured results show a bandwidth of 3.6 GHz from 12.1 to 15.7 GHz with return loss better than 19 dB and insertion loss less than 0.17 dB, which agree very well with simulated results.

A broadband suspended substrate stripline filter using dual-mode resonator

A broadband suspended substrate filter is proposed and implemented using dual-mode resonator aiming at transmitting the signals in the passband of 10–18 GHz. It is composed of two quarter-wavelength resonators and inductor. The inductor is a short-circuited stub. After optimization of this filter, a good bandpass behavior with 10 transmission poles is theoretically realized and experimentally confirmed. Within the whole BPF passband, the return loss is found better than 10 dB, and the insertion loss is less than 1.9 dB. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26070

MINIATURE SUSPENDED-SUBSTRATE BANDPASS FILTER

A new quasi-lumped suspended-substrate stripline structure admitting implementation of miniature highly selective narrowband filters is studied. Appreciable improvement of the device selectivity is achieved with supplementary strip conductors introduced between the resonators, which induce attenuation poles near both passband edges. Furthermore, these supplementary conductors reducing the coupling between the resonators allow diminishing the interresonator spacing and the total size. A four-resonator filter is synthesized using the intelligence optimization method. Experimental results of the manufactured filter are presented. Received 6 July 2010, Accepted 11 August 2010, Scheduled 16 August 2010 Corresponding author: V. V. Tyurnev (tyurnev@iph.krasn.ru).

Design of wideband diplexer in suspended substrate stripline medium

A wideband diplexer is designed and developed in suspended substrate medium using wide-bandpass filters of 1014 GHz and 1418 GHz. Tight coupling between resonators is achieved by etching the resona...

Design of a tri-section folded SIR filter

This letter reports the design of a suspended substrate stripline bandpass filter with relocatable second pass band using tri-section folded stepped impedance resonators (TFSIRs). Resonance conditions for the TFSIR in terms of impedance ratios have been derived. Location of the second pass band as a function of impedance ratios (of TFSIRs) has been studied in detail. Experimental results of a filter designed at 2.95 GHz with 31% bandwidth have been compared against the simulation results.

Second-harmonic suppressed SSS band pass filter

This paper presents parametric studies related to equalization of even- and odd-mode phase velocities in coupled suspended substrate striplines (SSSs). An SSS band-pass filter at 2.4 GHz with suppressed 2nd harmonic has been designed using the present phase-velocity equalization technique and experimental results of the filter are discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 600–602, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21419

Design of periodically elevated groundplane SSS band-pass filter with suppressed second harmonic

Using periodically elevated groundplane along the coupled line sections in the lower cavity of suspended substrate stripline (SSS), a parallel-coupled line band-pass filter having suppressed harmonic at 2f/sub 0/ has been designed. Even and odd mode phase velocities in each coupled line section at 2f/sub 0/ have been equalised by using the right number of periodic grounding cells with proper dimensions. Based on this equalisation technique, a filter at 2.4 GHz has been designed and fabricated to prove the concept.

Use of partially overlapped suspended substrate striplines for the realization of wideband microwave filters

This article presents realization of low loss, wide stop-band suspended substrate stripline (SSS) wideband pass filters using interdigital and stepped-impedance resonators. SSSs have been characterized using the finite-difference method (FDM). The experimental results of the fabricated filters are compared with the theoretical results. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.

On the design model of broadside-coupled SSS line for microwave integrated circuits

A practical design model for the analysis of broadside-coupled suspended-substrate stripline is presented. The modified design expression of the shielded microstrip line is valid for a wide range of structural parameters and dielectric constants, that is, 1.0 ≤ er ≤ 140.0 for dielectric constant, 0.1 ≤ w/h ≤ 10.0 for strip width with an accuracy of <0.5%. This design expression is further extended for broadside-coupled suspended-substrate stripline. The proposed broadside-coupled suspended-substrate stripline (BCSSS) expressions are valid over a practical range of structural parameters and dielectric constants. The validity range of this expression for structural parameters is 1.0 ≤ er ≤ 16.0 for dielectric constant, 0.1 ≤ w/b ≤ 2.0 for strip width, and s/b ≤ 0.5 for substrate thickness. The average accuracy of the present expressions is <0.6% and <0.2% for the even- and odd-mode effective dielectric constants, respectively, with maximum deviation less than 1.16% with respect to reference value. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 292–297, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20969