Volume 75, Issue 9-10

A compact dual-band balanced bandpass filter with high frequency selectivity and adjustable passband based on the perturbed circular substrate integrated waveguide cavity is firstly proposed in this paper. Two pairs of metallic vias are located at 45°direction of cavities to separate a pair of degenerate modes (TM 110 modes) to achieve the differential-mode (DM) dual-band response. Moreover, the perturbation vias can also be used to control the center frequency of the second DM passband while the first one still stays unaffected. The introduction of source-load coupling makes the filter exhibit excellent selectivity. And four controllable transmission zeros appear near two DM passbands. Finally, good common-mode suppression has been got owing to the proposed balanced structure. The measured results are in accordance with the simulated ones well.

This paper mathematically investigates a special kind of digital infinite-impulse response (IIR) filters, suitable for filtering out very low frequencies near zero from digital signals. We investigate the transfer functions of such filters from 1st to 3rd order and provide formulas to calculate the filter coefficients from the desired cutoff frequency.

In this paper, a wideband continuous pure right hand circularly polarized (RHCP), high gain, and low-radar cross-section (RCS) array antenna is proposed. A linear-to-circularly polarization conversion (LCPC) Metasurface (MS) is employed as the superstrate of the Fabry–Pérot (FP) resonator antenna, consisting of two oblique slits etched patches located at top and bottom, respectively, and a metal ring with corner-cutting patch inside, that ensure a wideband transmission and reflection LCPC frequencies ranging from 9 to 22 GHz, and 7–13.5 GHz, respectively. While, a pure RHCP LCPC frequency band of 9–12 GHz is produced by adopt the proposed MS that is benefit from the design of etched oblique slits and corner-cutting patch surrounded by the metal ring, where the magnitude and phase difference can be kept in the variation of ±3 dB and 10°, respectively. Then, a rectangle patch-fed MS FP antenna is designed by an arrangement of 5 × 5 MS unit cells. Following this, the sequence rotated technique is utilized to arrange the array antenna by 2 × 2 units, ensuring a wide band RCS frequency band. The proposed array antenna is fabricated and measured, which indicated the correctness of this design for performance of high gain, low RCS, and wideband pure RHCP. Compared with recent reported MS-based FP works, a wideband LCPC frequencies purity is obtained, and a good radiation and scattering performance is obtained in the design.

A single-layer wideband high efficiency reflectarray in Ku-band has been presented in this paper. A novel dual-resonant patch element approach has been analyzed and optimized to obtain good radiation performances within the operating frequency band. The phase shift range of 573° can be obtained with less steep linear phase shift curve. To compensate the differential spatial phase delays from the feed to the elements, the variable size technique has been utilized for obtaining required phase shifts. The reflectarray aperture has been designed, manufactured and measured. Measured results are in good agreement with the simulated ones. The measured gain of the reflectarray aperture at center frequency can reach 27.2 dBi, which is equivalent to aperture efficiency of 51.3%, and the 1-dB gain bandwidth of the aperture is 18.4%.

A bilayer split-ring chiral metamaterial converts the linearly polarized wave, into a nearly perfect left or right-handed circularly polarized wave. The proposed antenna is intended to operate at center frequency of 5.80 GHz with switchable polarization capability. The polarization re-configurability is achieved by electronically switching of two PIN-diode pairs, which are embedded into bilayer split-ring Chiral Metamaterial. The optimized length of rectangular patch is 16 mm and width is 12.1 mm. Two types of radiation characteristics offered by the proposed antenna; left hand circularly polarized in mode 1 and right hand circularly polarized in mode 2. Measured results show that its impedance bandwidth is 155 MHz from 5.70 to 5.855 GHz for both mode 1 and mode 2. The measured axial-ratio bandwidth is 100 MHz from 5.75 to 5.85 GHz for mode 1 and 110 MHz from 5.73 to 5.84 GHz for mode 2. Antenna has LHCP gain of 2.52 dBi and RHCP gain of −23 dBi in mode 1. RHCP gain of 2 dBi and polarization purity of about −20 dBi is obtained in mode 2. The proposed antenna has simple structure, low cost and it has potential application in field of wireless communication (i.e., WiMax, WLAN etc.).

A wideband circularly polarized (CP) array antenna has significant importance in modern communication system. In this paper, we proposed a wide band CP array by combing dual split ring resonators (DSRRs) to dual layer microstrip antenna. A 2 × 2 dual-layer microstrip antenna array is used to radiate wide band linearly polarized wave, and the 3 × 3 four-layer DSRRs is used as an external polarizer which converts linearly polarized wave to circularly polarized wave at distinct frequencies. The proposed array achieves an impedance bandwidth of 20% ranging from 4.57–5.57 GHz and AR bandwidth of 16.83% ranging from 4.57–5.41 GHz. The prominent futures of the proposed array are wide impedance bandwidth on desired frequencies. This new concept is theoretically and experimentally investigated to evaluate the performance of the proposed array, which allows a better prospect for the application of radar and satellite communication systems.

Open dielectric waveguides are structures used to guide electromagnetic energy in integrated circuits above the cutoff or as leaky wave antennas propagating the energy transversely out of the waveguide in a narrow region below the cutoff. In this study, the related operating regions for the hybrid EH modes of a cylindrical dielectric rod were obtained analytically. Analyses of the leaky wave characteristics of the hybrid EH modes for various radii of the rod and various dielectric constant values were performed. The guided modes existing above the cutoff with a pure real propagation constant, and the leaky wave modes existing below the cutoff with a complex propagation constant, were obtained from the coefficient matrix of the characteristic equations system of the structure using the bisection method and Davidenko’s method, respectively. Additionally, the guided modes of the structure were obtained and designated in the light of previous studies in the literature. The results show that the frequency spectrum of the antenna mode region increases as the value of the dielectric constant and the radius of the dielectric rod decrease. In addition, a circular dielectric with a smaller radius and dielectric constant had a larger frequency spectrum in the leaky wave antenna applications.

A square dielectric resonator antenna (SDRA) offering high polarization purity as a feed for parabolic reflector antenna is presented in this paper. Three sequences of holes are strategically integrated into the SDRA to enhance the polarization purity of the desired mode by suppressing the cross-polarization (X-pol) generating higher order mode. A detailed study on the performance of the parabolic reflector antenna with the proposed SDRA feed is also performed. The composite structure provides low X-pol levels of −33 dB at the half-power beamwidth (HPBW) points and −35 dB at the 1 dB co-polarization region in the H-plane. The composite structure radiates in the broadside direction with a high gain of 26 dBi and radiation efficiency of 95%. The proposed SDRA is designed to operate at 3 GHz of the S-band. A prototype of the proposed design is fabricated and experimentally verified. A measured X-pol isolation of 39 dB at ±15% of HPBW (European Telecommunication Standards Institute [ETSI] standard for satellite communication) and 50 dB at boresight is obtained in the H-plane. The small size, light weight, stable radiation performance and high polarization purity offered by the proposed SDRA make it a suitable candidate for satellite communication application.

A new wideband omni-directional compact rectangular ring dielectric resonator antenna (RRDRA) fused with slotted bevel shaped patch antenna is presented for the ultra-wideband (UWB) applications. The RRDR (rectangular ring dielectric resonator) is employed to generate lower order radiating modes with merge with the modes of patch to obtain high impedance bandwidth in UWB region. Further, RRDR use led to reduction in overall conductor loss to achieve high radiation efficiency. The proposed RRDRA structure achieved an impedance bandwidth covering the frequency range from 2.6–15.6 GHz, or ∼142%. The measured results show that the proposed DRA provides peak measured gain of 6.2 dBi and radiation efficiency of 90% at resonant frequency 6.3 GHz with stable omni-directional monopole like radiation patterns with low cross-polarization. The proposed antenna has a short ground plane of size 40 × 40 × 11.6 mm 3 or ∼0.34 λ 0  × 0.34 λ 0  × 0.10 λ 0 at 2.6 GHz.

This paper presents a miniaturized dual-element Super-Wideband (SWB) Multiple-Input-Multiple-Output (MIMO) antenna. The operation bandwidth is enhanced by 175% with a Bandwidth Dimension Ratio (BDR) of 6960, using a tapered microstrip line and employing an improved isolation technique. An inverted T-slot is used in the partial ground plane of the antenna. Isolation is increased up to 25 dB over the operating band (1.6–24.5 GHz) by using a pair of T-shaped stubs and a rectangular strip between them. A detailed analysis of the parameters Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Mean Effective Gain (MEG), Total Active Reflection Coefficient (TARC), isolation between the ports, and Channel Capacity Loss (CCL) is undertaken to investigate the performance of proposed SWB MIMO antenna. A prototype of the proposed design is developed by fabricating on the FR–4 (loss tangent 0.02) dielectric substrate of electrical dimension 0.18 λ 0  × 0.14 λ 0 . The measured parameters are in good agreement with the simulated ones. The proposed antenna focusses on 2.4–2.483 GHz frequency band (Bluetooth) and 3.4–3.6 GHz frequency band with a center frequency of 3.5 GHz (as part of the sub 6 GHz 5G band).

A wireless frequency shift keying (FSK) transceiver that can simultaneously transmit and receive over the same radio channel using a novel complex baseband technique is introduced. The proposed design combines a traditional FSK modulator with a new frame-based demodulation technique able to recover data without using traditional cancellation techniques. Self Interference (SI) level has no impact on demodulation and can be ignored. The mathematical equations are detailed and validated by simulation. The implementation through software defined radio (SDR) using Ettus B210 USRP and GNU Radio proves that the system works properly and enables the In-Band Full-Duplex (IBFD) for FSK. An example of one single hope real-world IBFD communication is presented. Energy efficiency and System performances have been also evaluated using the bit error rate (BER) curve and discussed. The proposed technique enhances the spectral efficiency by factor 2 and seems very useful for low-rate applications such many internet of things (IoT) devices.

Emerging technologies, such as the Internet of things (IoT), machine learning (ML) and machine-to-machine networks encourage deployment of large-scale wireless sensor networks (WSNs). The major problem in WSN is the limited energy of node batteries. Therefore, the efficient use of node energy for data sensing, processing and communication operations is important to maintain a fully operational network for longest period of time. Literature presents a wide range of lifetime maximization techniques for WSN such as resource allocation algorithm, clustering and routing, sleep–wake scheduling, energy harvesting, MIMO technique, Distributed source coding, genetic algorithm and sink mobility. These techniques effectively lessen the energy consumption and enhance the lifetime of the entire wireless sensor network in various applications. Besides energy consumption, the characterization parameters such as coverage and connectivity, communication and modulation schemes, operational environment, network parameters, node parameters and service parameters also have great impact on WSN performance. This paper presents a comprehensive survey of state-of-the-art research works that improves the performance of WSN by optimizing various network characterization parameters and lifetime maximization techniques. These results highlight the key issues which affects WSN performance and provide a roadmap for WSN designers for effective implementation of novel WSN strategies.