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

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.

This paper proposes a novel scheme for developing a linearly polarized (LP) hybrid antenna using a simple integration of a planner cavity-backed antenna with a conventional rectangular patch antenna. To substantiate, a half-mode rectangular substrate-integrated waveguide technique is divided into halves to reduce the size and later integrated with a patch antenna. The patch antenna is getting excited by the mutual coupling of TE₁₀₁ mode and resonating in the vicinity of the cavity resonator. These two different combinations of strategy let the antenna obtain superior characteristics such as bandwidth and gain. To make this structure enable to use in the planner circuit, a 50 Ω microstrip line is incorporated. This proposed hybrid antenna is simulated and tested experimentally to justify its worthiness. The simulated and measured data maintained good agreements regarding S₁₁, bandwidth, gain, radiation pattern, and efficiency.

In the paper, a wideband tunable 4 × 4 Nolen matrix is proposed. By using the presented topology of the Nolen matrix, tunable output port phase differences can be realized by inserting one type of tunable phase shifters (T-PS). Besides, the in-band phase deviation error is minimized by adding compensation phase shifters (C-PSs) to the output ports of the Nolen matrix. Analytical design methods based on signal flow graphs and complex exponential signal are given to obtain the rigorous relationships of the coupling and phase shifts in the Nolen matrix. Besides, a detailed method for output ports phase slope compensation is provided. For validation, a prototype centered at 5.8 GHz is designed and fabricated. Measurement results agree well with the simulated ones. By using only one voltage to control the phase shifts of the T-PS in a 90° range for each input excitation of the Nolen matrix, a full 360° range of the progressive phase difference is realized by switching four input ports. The measured fractional bandwidth under 10 dB return loss and isolation is larger than 24.5% with the in − band ± 1.5 dB amplitude imbalance and ±15° phase deviation error for ports 1-4 excitations. Besides, for a more strict criterion of ±1 dB amplitude imbalance and 10° phase deviation error, the measured bandwidths are larger than 15% for all port excitations.

We propose a new dual-band passive RFID tag antenna design by combining a rectangular spiral coil and patch-meander-line dipole with an interconnected structure. This design enables operation in high-frequency (HF) and ultra-high-frequency (UHF) RFID systems, suitable for energy harvesting and tracking applications. The simulations by the CST full-wave software demonstrate conjugate impedance matching between the tag antenna and two RFID tag chips. At 13.56 MHz (HF), the tag antenna exhibits an inductive reactance of 422.79 Ω, while at 922.5 MHz (UHF), it presents an impedance of 9.41 + j174.96 Ω. The antenna generates a maximum magnetic field intensity of 0.5 A/m and omnidirectional electromagnetic fields with an antenna realized gain of -4.26 dBi at 922.5 MHz. We also analyze the impact of the tag antenna combination using numerical software. Furthermore, we fabricate a prototype tag antenna and validate its performance with RFID readers. The proposed tag antenna achieves the maximum read ranges of 11 cm and 6.9 m for the HF (13.56 MHz) and UHF (920-925 MHz) bands, respectively, accompanied by the energy harvesting of 1.48 volts at the HF band by the coupling magnetic field received by the HF antenna to the chip ST25DV04K at the output voltage pin.

To enhance filter performance in terms of stopband, we propose a wide-stopband substrate-integrated waveguide filter based on the rejection of higher-order modes. The filter establishes the inner and outer coupling windows at the mode’s weakest electric field to achieve mode suppression. Simultaneously, we employ the electromagnetic hybrid coupling theory to analyze the electromagnetic distribution of the particular modes and determine the dimensions of the coupling circular apertures and slits based on the extracted coupling coefficients to attain suppression of the specific modes. The filter successfully suppresses all higher-order modes having resonant frequencies below that of the TE₁₅₀ mode, as demonstrated by simulation results. We conducted measurements and found that the filter has a center frequency of 4.78 GHz, a bandwidth of 100 MHz with a -3 dB attenuation, and a stopband of -25 dB that extends up to 16.62 GHz (i.e., 3.48 times the center frequency). Simulation and measurement results demonstrate a good correlation. This method, compared to other SIW filters, is easy to design, has a wider stopband range, can be readily applied to practical microwave communication systems, and has potential applications.