International Journal of RF and Microwave Computer-Aided Engineering最新文献

In this article, a simple approach for achievement of flexible coupling is presented based on the half-mode substrate-integrated waveguide (HMSIW). Since both electric and magnetic fields vary along the magnetic wall of the HMSIW, there exists mixed coupling between two adjacent HMSIWs. In this context, only by adjusting the width of the coupling slot at specific regions, both coupling property and strength can be conveniently controlled. Besides, as the coupling slot possesses the merits of simple structure and high flexibility, it is also expected to achieve desired couplings between multimode resonators. For demonstration, three cross-coupled bandpass filters (BPFs) with different kinds of frequency responses are constructed based on the typical cascaded trisection coupling topology by mixing one SIW and two HMSIWs, including two single-band and one dual-band designs. All measured results are highly consistent with the simulated ones, validating that the HMSIW not only has the inherent advantage of smaller size than the conventional SIW counterparts but also possesses unique feature in providing flexible coupling without extra circuit.

This letter presents a multifunctionality reconfigurable substrate-integrated waveguide (SIW) filter embedded in a microstrip line. The proposed filter used an electromagnetic bandgap structure (EBG) to compact the size and improve the electromagnetic features. The SIW filter consists of a three-cell EBG with metallic circular-shaped connected to the ground through cylindrical vias. Firstly, the base SIW structure offers a wide passband filtering response, and then, to obtain selective passband, wide band rejection, and controllable resonance frequencies, a three-cell EBG along with four diodes has been attached. The filter is designed and printed on a Rogers 4003 substrate with a thickness of 1 mm and is experimentally validated for functionalities operated at three modes with an average 3 dB bandwidth of 115 MHz in each frequency. In addition to that, two transmission zeros (TZ) have been produced in the upper band frequency. The filter’s response is also tunable by turning the diode off or on and changing the main parameters of EBG, the gab, and the position between cells. The study explores resonance frequency alterations in a three-state system of on/off. By eliminating or diminishing specific modes, and incorporating diodes, distinct resonance behaviors are observed. Moreover, shifting frequency resonance in a multiparameter system has been investigated. Increasing B1 induces a significant shift to lower values, while an increase in D1 leads to a decrease in the first and second resonance frequencies and an upward shift in the third. The designed filter has been fabricated and tested to compare and confirm simulated responses. Simulation and measurement results are in good agreement. The S-parameters of measured results gained a good response (>15 dB) within the passbands and stopbands and an insertion loss of 1.5 dB suitable for 5G and Wi-Fi systems.

In this paper, a collaborative control method of transmission amplitude and phase for transmitarray antenna (TA) design is proposed. In this proposed method, one of the most popular hypersurface fitting models, Gaussian stochastic process (GP) model, is utilized to construct an accurate surrogate model. Following this implementation, a mapping relationship between structural parameters of TA unit cell and its transmission amplitude and phase is established. The most advantage of this method is its applicability for general TA designs because it is much difficult to control the amplitude and phase of unit cell independently through adjusting separate structural parameters. To verify the high efficiency of the proposed method, three TA antennas with different scanning angles are designed to obtain high sidelobe suppression level. Measured results show that the proposed collaborative control method of amplitude and phase is much promising for high sidelobe suppression level in TA designs.

In this paper, a low-profile co-linearly polarized simultaneously transmit-receive antenna (STRA) terminal is presented for 5G and upcoming technologies. The proposed STRA terminal comprises of an identical pair of spatially rotated half-circular microstrip antennas for transmission (Tx) and reception (Rx). The challenge of self-interference (SI) is addressed by employing passive SI cancellation techniques such as spatial diversity, field confinement, and surface perturbations. This has been accomplished by using fence-strip structure and V-shaped slots in the ground plane. The STRA was designed, fabricated, and tested for full-duplex operation in a sub-6 GHz band lying from 5.73 to 5.88 GHz, providing high interport isolation ranging from 35.5 dB to a maximum of 46.5 dB. The proposed STRA was implemented using Rogers 3003™ substrate. The measurements yield radiation characteristics with high gain of 5.45-6.0 dBi and 5-6.5 dBi for Tx and Rx antennas, respectively. The measured results are in good conformance with the simulated design. This antenna finds its potential usage in V2X and private 5G networks and can be extended for full-duplex MIMO implementations.

This paper presents a low-profile dual-band microstrip patch antenna operated at the 2.45/5.8 GHz ISM bands, targeting wireless body area network (WBAN) applications. The proposed antenna is fabricated on a jean substrate measuring 74 × 82 mm². The four corners of the conventional rectangular patch are cut to activate an additional operating frequency and to enhance the radiation pattern. The circular slot is added to the radiating patch to fine-tune the desired frequencies. The measured impedance bandwidth of the proposed antenna at 2.45 GHz and 5.8 GHz bands is 3.68% (2.40 GHz–2.49 GHz) and 3.81% (5.67 GHz–5.89 GHz), respectively. The measured maximum gains are 3.08 dBi at 2.45 GHz and 2.15 dBi at 5.8 GHz. Moreover, the antenna’s performance when placed on flat and rounded body surfaces is also investigated. The proposed antenna achieves stable radiation pattern and low specific absorption rate (SAR) value with low complexity in design. The results indicate that the proposed antenna can be a promising candidate for WBAN applications.

This paper presents the design and measurements of a 215-252 GHz 40 nm bulk CMOS frequency doubler with a 6.8 dBm deliverable peak output power and a conversion gain of 11.8 dB. The designed chip is composed of a 28.5 dB gain 6-stages 110 GHz power amplifier, an optimized push-push doubler biased in class-C configuration, and an output impedance matching network. A numerical method had been applied here for designing each implemented matching network achieving the optimum matching while maintaining the minimum insertion loss as well. The presented design shows the highest output power among the other sub-THz-designed CMOS counterparts. The design occupies an area of 0.795 mm² and shows a total DC power dissipation of 262 mW and DC-RF efficiency of 1.87%.

In this research work, the design of a dipole antenna based on metamaterials is proposed, which can be used as a high gain multiband communication device for RFID applications. This antenna is printed on two sides of an Arlon substrate, which has an overall electrical dimension of 0.39 λ₀ × 0.11 λ₀ × 0.0014 λ₀. The metamaterials are used to obtain a multiband antenna, and their integration technique into the antenna results in a high gain compared to a conventional antenna without any magnification or additional layer. The simulated and measured results show that the proposed antenna can operate at 0.88-0.97 GHz, 2.41-2.48 GHz, and 5.77-5.91 GHz with a reflection coefficient of less than −10 dB, which make it well suited for RFID at 860-960 MHz and 2.4 GHz/5.8 GHz. All these resonant frequencies show better impedance matching with high gain. The proposed antenna has the advantages of simple design, low profile, easy feeding, low manufacturing cost, and easy integration into the electronic circuit.

This paper presents a lumped-element wideband directional coupler that enables arbitrary impedance matching and harmonic suppressions from 2f₀. The coupler consists of four filtering networks (FNs) and an asymmetric branch-line hybrid serving as the matching network. The use of lumped-element topology helps reduce circuit size and improve harmonic suppressions. Each FN, composed of two lumped-element resonators, contributes two additional transmission poles, enabling bandwidth scaling, bandwidth enhancement, and harmonic suppressions. To demonstrate the effectiveness of the proposed design, a wideband coupler with various terminal impedances operating at 0.5 GHz is designed, simulated, and fabricated. The measured size is $$, the fractional bandwidth for –14.3 dB return loss is 46%, and the harmonic suppression is more than –30 dB from 0.69 to 4.5 GHz.

In the present article, a design approach to accomplish circular polarization-based rhombus ring microstrip-fed monopole antenna working at 5.8 GHz for wireless body area network (WBAN) applications is proposed. The input impedance calculation using an electromagnetic theory of transmission line in a travelling wave coupled to the parallel-plate inductor model is conducted. Radiated electric field pattern calculation of the conventional square ring microstrip patch antenna (MSPA) using Biot and Savart’s law is reported. The circular polarization of the proposed antenna is accomplished by loading the radiating path with a capacitive element sectioned in the neighbourhood of the feed line. The proposed planar monopole antenna of volume 0.38λ₀ × 0.38λ₀ × 0.029λ₀ (λ₀ is evaluated at the resonant frequency of 5.8 GHz) achieves a -10 dB impedance bandwidth of 86.20% in the band (3-8 GHz) with a stable real gain of 8.29 dBic in circular polarization at the resonant frequency of 5.8 GHz and axial ration bandwidth of about 32.75% in the (5-6.9 GHz) band. Specific absorption rate (SAR) evaluation of the studied antenna is computed numerically on a part of the human phantom model to justify its use in WBAN applications. It is noted that the maximum amount of radiation absorbed by a part of the human phantom model is limited to a maximum SAR value of 1.45 W/kg and 0.754 W/kg on 1 g and 10 g of tissue mass, respectively. The prospective design has been fabricated and tested, and the experimental results are in good agreement with the simulation outcomes.