A tunable multilayer diplexer using substrate integrated waveguide (SIW) technology is proposed in this letter. A multilayer design is chosen to easily control the electric and magnetic coupling ...through circular slots in order to achieve a wide-stopband response. The proposed diplexer works at two unique frequencies (centered at 10.5 and 13.5 GHz) with high isolation (>42dB) and a wide stopband (up to 21 GHz). A varactor diode is used in the proposed diplexer for tuning. The varactor diode is placed in the structure in such a way that both channels can be tuned independently without affecting one another. The results show the flexibility of the diplexer in achieving desired responses and its suitability for integration with any tunable component. Simulated and measured results obtained are in good agreement.
In this brief, a dual-mode dual-band filter based on half-mode substrate integrated waveguide (HMSIW) is presented. The proposed filter has the capability to tune the two pass-bands independently. ...The proposed filter consists of two HMSIW resonators coupled through a pair of E-shaped coupling slots. Two resonating modes (TE 101 and TE 102 ) are excited in each resonator. A varactor diode is used in the proposed filter for tuning purpose. The varactor diode is placed in the structure in such a way that both bands can be tuned independently. The lower passband can be tuned from 3.26 to 3.47 GHz with insertion loss of 0.2-2.9 dB. The higher passband can be tuned from 5.47 to 6.13 GHz with low insertion loss of 0.1-2.1 dB. The presented results show the flexibility of the filter to achieve desired responses and its suitability for integration with any tunable planar structure. A good agreement between the simulated and measured results is observed.
QMSIW-Based Single and Triple Band Bandpass Filters Iqbal, Amjad; Tiang, Jun Jiat; Wong, Sew Kin ...
IEEE transactions on circuits and systems. II, Express briefs,
07/2021, Letnik:
68, Številka:
7
Journal Article
Recenzirano
This brief proposes compact and planar substrate integrated waveguide (SIW)-based filters for single and triple band operations using two quarter-mode SIW (QMSIW) cavities. Two miniaturized QMSIW ...cavity resonators (QMSIWCRs) are capacitively coupled. Miniaturization in the QMSIWCR is achieved by adding an arc-shaped slot and a rectangular open-ended stub at the closed-end of the QMSIWCR. In the triple band bandpass filter (BPF), a capacitor is added to the open-ended side of the stub to enhance impedance matching at the higher modes. It has the centre frequencies of 2.1, 3.98 and 6.6 GHz with an insertion losses (ILs) of 0.93, 0.98, and 1.2 dB at the lower, middle and upper passband, respectively. Moreover, the measured fractional bandwidths (FBWs) are 16.97, 8.77, and 8.42% at the lower, middle and upper passband, respectively. Two rectangular slots are etched on the upper layer of the cavity to suppress the second mode and reduce coupling of the third mode; this realizes a single-band filter with an improved upper stopband response. It has the centre frequency of 2.1 GHz with a wide upper stop-band response, having a rejection level of 20 dB up to <inline-formula> <tex-math notation="LaTeX">3.19f_{c} </tex-math></inline-formula>. The operation of filter is additionally discussed and verified by means of a lumped element equivalent circuit model and experimental results. The proposed filters are suitable for integration with other planar radio-frequency (RF) components due to their compact sizes, low ILs, planar structures, multiple transmission zeros (TZs) and adequate bandwidths.
This article proposes a quad-band multiport harvester that can scavenge ambient radio frequency (RF) energy of available frequency bands (i.e. GSM-900, GSM-1800, 3G and Wi-Fi) efficiently. This ...design's novelty is the use of frequency-dependent multiple antenna ports that enables the harvester to fully exploit all available frequency bands, spatial diversity, and polarization for maximizing the harvested RF energy at a lower power density level in an ambient environment. Indistinctly, the proposed antenna consists of 8-port which maintain <inline-formula> <tex-math notation="LaTeX">0.33\lambda \times 0.33\lambda </tex-math></inline-formula> (i.e. wavelength <inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula> calculated at 0.9 GHz in free space) average area per port and has achieved more than 35% relative bandwidth (BW) with a maximum gain of 6.5 dBi to cover the selected frequency bands. Besides, the proposed quad-band rectifier with a multi-stub impedance matching network is feasible for RF harvesting over the available ambient frequency bands. The proposed rectenna's measurement results show that the generated average dc output voltage is increased up to 0.750 V at a low RF input power density of −27 dBm for a load resistance of 2.11 <inline-formula> <tex-math notation="LaTeX">\text{k}\Omega </tex-math></inline-formula>. The overall dc rectification efficiency of the 8-port pixel harvester is also assessed and depicted to be 66.52% when the resultant RF input power density level is −27 dBm. Measurement in an ambient outdoor and controlled indoor environment is also conducted, demonstrating that the new 8-port pixel RF harvester can produce a dc output voltage of 0.797 V which is greater than some of the reference RF harvesters.
SIW Cavity Backed Self-Diplexing Tunable Antenna Iqbal, Amjad; Tiang, Jun Jiat; Lee, Ching Kwang ...
IEEE transactions on antennas and propagation,
08/2021, Letnik:
69, Številka:
8
Journal Article
Recenzirano
This communication presents a compact quarter-mode substrate integrated waveguide (QMSIW) cavity-backed self-diplexing tunable antenna. An open-ended slot is used to split the circular half-mode SIW ...(HMSIW) cavity resonator into two QMSIW cavity resonators. A varactor diode-loaded stub is added with each QMSIW resonator to achieve miniaturization and resonant frequency tuning. The miniaturization and tunability technique is demonstrated in a stand-alone QMSIW resonator and also in a QMSIW based self-diplexing antenna. The antenna is simulated, optimized, and subjected to practical testing inside a rectangular device. The device is treated as a quasi-receiver/transmitter, which consists of electronic circuitry and the proposed antenna. The resonant frequencies can be independently tuned by changing the values of the varactor diodes connected with each resonator. The simulated and measured results confirm that the proposed antenna can be tuned from 3.77 to 4.59 and from 4.96 to 6.1 GHz in the lower and higher frequency bands, respectively. The isolation between the two resonators in both bands is always better than 21 dB. The measured gains vary from 4.85 to 5.87 and 4.87 to 6.5 dBi in the lower and higher frequency bands, respectively. The proposed design shows stable and unidirectional radiation patterns in all tuning cases in both bands. The proposed self-diplexing tunable antenna is a competitive choice in compact and spectral-efficient radio frequency (RF) front ends where tuning is necessary for the efficient use of the frequency spectrum.
Fifth generation (5G) is a recent wireless communication technology in mobile networks. The key parameters of 5G are enhanced coverage, ultra reliable low latency, high data rates, massive ...connectivity and better support to mobility. Enhanced coverage is one of the major issues in the 5G and beyond 5G networks, which will be affecting the overall system performance and end user experience. The increasing number of base stations may increase the coverage but it leads to interference between the cell edge users, which in turn impacts the coverage. Therefore, enhanced coverage is one of the future challenging issues in cellular networks. In this survey, coverage enhancement techniques are explored to improve the overall system performance, throughput, coverage capacity, spectral efficiency, outage probability, data rates, and latency. The main aim of this article is to highlight the recent developments and deployments made towards the enhanced network coverage and to discuss its future research challenges.
A compact quarter-mode substrate integrated waveguide (QMSIW)-based self-quadruplexing antenna is proposed for compact radio frequency (RF) front ends. The QMSIW-based self-quadruplexing antenna has ...four unequal resonators resonating at the Industrial, Scientific, and Medical (ISM) band (2.45 GHz), fifth-generation (5G) band (3.5 GHz), wireless local area network (WLAN) band (4.9 GHz), and wireless fidelity band (5.4 GHz). All four resonators radiate through the open-ended wall of the QMSIW resonator and the arc-shaped slot inside the cavity. By properly optimizing the locations and dimensions of the resonators, higher isolation (<inline-formula><tex-math notation="LaTeX">></tex-math></inline-formula>29.9 dB) is gained. In fact, all four resonators operate on a common grounded substrate with negligible interference. A dummy rectangular device is used to keep the printed circuit board (PCB) and antenna in it to measure the S -parameters and radiation properties. The proposed antenna has a lower circuit size (0.23<inline-formula><tex-math notation="LaTeX">\lambda _{g}^{2}</tex-math></inline-formula>), reasonable gain (<inline-formula><tex-math notation="LaTeX">></tex-math></inline-formula>3.85 dBi), high efficiency (<inline-formula><tex-math notation="LaTeX">></tex-math></inline-formula>82.7 %), and high isolation (<inline-formula><tex-math notation="LaTeX">></tex-math></inline-formula>29.9 dB). Based on the above-mentioned attributes, it is a good candidate for compact RF front ends.
This article presents the detailed theoretical, simulation, and experimental analysis of a half-mode substrate integrated waveguide (HMSIW)-based multimode wideband filter. A third-order, ...semicircular HMSIW filter is developed in this paper. A semicircular HMSIW cavity resonator is adopted to achieve wide band characteristics. A U-shaped slot (acts as a λ/4 stub) in the center of a semicircular HMSIW cavity resonator and L-shaped open-circuited stubs are used to improve the out-of-band response by generating multiple transmission zeros (TZs) in the stop-band region of the filter. The TZs on either side of the passband can be controlled by adjusting dimensions of a U-shaped slot and L-shaped open-circuited stubs. The proposed filter covers a wide fractional bandwidth, has a lower insertion loss value, and has multiple TZs (which improves the selectivity). The simulated response of filter agrees well with the measured data. The proposed HMSIW bandpass filter can be integrated with any planar wideband communication system circuit, thanks to its planar structure.
For low input radio frequency (RF) power from -35 to 5 dBm, a novel quad-band RF energy harvester (RFEH) with an improved impedance matching network (IMN) is proposed to overcome the poor conversion ...efficiency and limited RF power range of the ambient environment. In this research, an RF spectral survey was performed in the semi-urban region of Malaysia, and using these results, a multi-frequency highly sensitive RF energy harvester was designed to harvest energy from available frequency bands within the 0.8 GHz to 2.6 GHz frequency range. Firstly, a new IMN is implemented to improve the rectifying circuit's efficiency in ambient conditions. Secondly, a self-complementary log-periodic higher bandwidth antenna is proposed. Finally, the design and manufacture of the proposed RF harvester's prototype are carried out and tested to realize its output in the desired frequency bands. For an accumulative -15 dBm input RF power that is uniformly universal across the four radio frequency bands, the harvester's calculated dc rectification efficiency is about 35 percent and reaches 52 percent at -20 dBm. Measurement in an ambient RF setting shows that the proposed harvester is able to harvest dc energy at -20 dBm up to 0.678 V.
With the rapid growth of data traffic and mobile devices, it is imperative to provide reliable and stable services during mobility. Heterogeneous Networks (HetNets) and dense networks have been ...identified as potential solutions to address the upcoming capacity crunch, but they also pose significant challenges related to handover optimization. This paper presents a comprehensive review of recent handover decision algorithms in HetNets, categorizing them based on their decision techniques and summarizing their input parameters, techniques, and performance evaluations. Our study highlights the technical challenges and opportunities related to handovers in HetNets and dense cellular networks and provides key findings from recent studies. The significance of this survey is to provide a comprehensive overview of handover decision algorithms in HetNets and dense cellular networks, which can aid in the development of more advanced handover optimization approaches.
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