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

In this paper, a planar antenna structure-based compact high gain wideband antenna array is presented for 5G millimeter wave applications. The proposed array uses a 1-to-8 power divider to feed eight antenna elements arranged linearly. To enhance the gain, multiple slits and I-slots are placed on the ground plane and feeding network, respectively. To further improve the gain of the design, an L-shaped metallic reflector is positioned at the optimum distance. With a large 10 dB bandwidth of 35.93% from 22.6 to 32.5 GHz, the proposed antenna array operates in the two 5G bands of 26 GHz and 28 GHz. The proposed antenna array’s measured gain varies from 9.18 to 13.22 dBi which is higher than the gain of 6.60–10.45 dBi of the unmodified array for the entire operating range. The antenna array shows a narrow beamwidth of 6.25° in its E-plane and radiates in end-fire direction. The overall dimension of the proposed antenna array is 57 mm × 25.978 mm × 0.787 mm, which features a simple, compact design. This antenna can be used for millimeter wave application as it fulfills all the requirements of future 5G applications at 26 and 28 GHz bands.

Cancer is a significant disease that often results in severe side effects from traditional treatments. Microwave hyperthermia has emerged as a minimally invasive, highly effective, and low-toxicity treatment option that has gained widespread use in recent years. The primary objective of this study is to develop and assess a miniaturized slit patch antenna designed to operate at 2450 MHz for hyperthermia therapy. The octagonal antenna patch features four symmetrical slots to reduce its size, enhance directional radiation, and improve focusing and penetration depth. Additionally, a metal cavity is incorporated at the top of the antenna to create a gap between the antenna and the skin, allowing for skin heat dissipation, improved impedance matching, reduced outgoing radiation, and enhanced directional radiation. The performance of the antenna is assessed based on specific absorption rate (SAR), penetration depth (PD), and effective field size (EFS). Subsequently, the antenna is fabricated and tested in pork tissue, with the measured results demonstrating good agreement with the simulated outcomes.

A novel hybrid bandpass filter (BPF) with wideband and high selectivity is proposed in this paper. The hybrid BPF is composed of two film bulk acoustic resonator (FBAR) cells and three lumped component resonators realized by the integrated passive device (IPD) technology. The ABCD matrix to S-parameters matrix method is used to calculate the frequency response of the BPF. Moreover, the expressions of transmission zeros (TZs) have been extracted. In the design process, an iterative design approach is proposed to improve the circuit and layout of the hybrid filter based on the packaged acoustic-electric hybrid simulation effect. Finally, two parts of the filter are packaged based on the flip-chip method, and two prototypes for the BPF are measured. The measured results of two chips with 3 dB fractional bandwidth of 13.7% and 15.8% are designed and fabricated, which verifies the validity of the proposed design principle.

In this article, a novel design approach to wideband dual-mode resonant circularly polarized (CP) antenna is advanced. An analytical design approach with low complexity as supported by a set of closed-form formulas is presented. Thus, the wideband dual-mode CP characteristics can be forward predicted and simply realized by incorporating stub asymmetry-enabled self-phase-shift dipoles and unequal feeding branches. At first, stubs are employed to broaden the impedance bandwidth by simultaneously exciting dual resonant modes. Then, the phase quadrature and equal magnitude conditions for wideband CP can be automatically realized by incorporating unequal Y-shaped microstrip branches and asymmetric slotline stubs. Finally, the coincidence between the simulated and measured results of the fabricated prototype antenna further confirms the feasibility of the design approach. It is shown that the presented antenna can exhibit an impedance bandwidth of 20.1% and a 3 dB axial ratio bandwidth of 16.3% in the boresight direction.

This paper presents the design of a frequency-tunable substrate-integrated waveguide (SIW) band-reject filter, specifically for spectrum underlay cognitive radio operation. The proposed filter has a simple tuning circuit but provides a wide frequency tuning range from 2.9 to 4.4 GHz (41%). The second resonant mode has been suppressed using a simple quadrature coupling; hence, the fundamental mode bandwidth of the filter has been increased from 2.08 GHz to 3.36 GHz. Due to its wide tuning range, simple tuning circuit, and increased fundamental mode bandwidth, the proposed filter is greatly important in underlay cognitive radio construction. The second-order filter has also been developed, and its performance is analyzed with both simulation and measurement. It gives a tunable bandwidth of 41%, an insertion loss of more than 10 dB, and a fundamental mode bandwidth of 3.36 GHz. The filter performance is also analyzed after connecting it to the standard horn antenna. Finally, from the total efficiency plots, it has been concluded that the proposed filter achieves all the above advantages with a low-lossy nature.

A 4 × 4 Isotropic Homogeneous Metasurface (IHM) backed, rectangular slotted dual-layered triband microstrip patch antenna (MPA) is proposed in this article. A detailed mathematical way to analyze the tensor surface impedance matrix (TSIM) of the proposed 4 × 4 IHM and slotted patch is demonstrated. The proposed IHM-backed MPA has a triband even-mode resonance at f_r0 = 2.45 GHz, 2f_r0 = 5.4 GHz, and 4f_r0 = 7.7 GHz. A better and more accurate estimation of bio-superstrate loading effect for triband resonance is employed using the human skin (ε_r = 52.79, σ_s = 1.39) and blood (ε_r = 52.8, σ_s = 1.23) layer on the top of dual-layered metasurface-backed slotted MPA. TSIM characterization is observed for both blood- and skin layer-loaded dual-layered metasurface-backed slotted MPA. Chicken breast (ε_r = 55.2, σ_s = 1.49, and tanδ = 0.325) with blood (ε_r = 58.2, σ_s = 2.59, and tanδ = 0.364) is loaded onto fabricated dual-layered structure to verify numerically modeled estimation. A closed form triband, even-order resonance mode (i.e., f_r0, 2f_r0, and 4f_r0) estimation based on dielectric superstrate thickness (H_s) is numerically established using MATLAB solver. Complete measurement setup with simulated vs. measured results is compared in this article.