Jing-Li Guo

This paper addresses the computational inefficiency of reflection coefficient calculation for loaded antennas under Continuous-Wave (CW) electromagnetic illumination. A rapid calculation method based on multi-port network S-parameters is proposed. By establishing a network model incorporating radiation and load ports, the loaded antenna system is characterized as a scattering parameter matrix. Under the premise of maintaining invariant network topology, this method enables rapid re-calculation of reflection coefficients through updating load parameters only, effectively avoiding repetitive full-wave simulation modeling in conventional approaches. A genetic algorithm optimization framework is subsequently developed based on this methodology, successfully designing an elliptical illuminator antenna with near-field horizontally polarized plane-wave simulation characteristics. Simulation results demonstrate that the optimized antenna achieves VSWR below 2.7 across the 0.1 MHz-30 MHz operational bandwidth, while the dominant polarization component of the electric field in the test area satisfies ≥0.1 V/m (0.1 MHz-1 MHz) and ≥1 V/m (1 MHz-30 MHz), fully complying with the IEC 61000-4-23 illumination compliance thresholds.

A novel data-based method for fast calculation of radar echo in near-field (NF) regions is presented in this letter. Newly defined generalized radar cross section (GRCS) data for target and near-field aperture characterized (NFAC) data for radar antenna are used, which is built on the Huygens surface surrounding the targets and antennas. The new GRCS data are only related to the scattering properties of the targets, and can be decoupled from the antenna in the NF region. The GRCS data and NFAC data can be used to replace the target and antenna in the radar echo simulation, and the radar echo simulation is transformed into data processing, which can make the calculation much faster compared to the electromagnetic (EM) simulation. The simulation progress is introduced in detail and some examples are given for verification. The simulated results show the effectiveness of the proposed method.

A low-profile wide-angle coverage antenna for Ad Hoc communication networks is presented in this letter, which consists primarily of a rotationally symmetrical structure with a microstrip patch antenna positioned at its center. Utilizing two orthogonal coupling feeds, the microstrip antenna produces circularly polarized radiation in the broadside direction. Meanwhile, the rotationally thin structure is driven by the coupling of the microstrip patch, and a linearly polarized radiation out of the range of ±15° is generated. Due to this parasitic structure, the radiation of the whole antenna at the upper hemisphere is balanced greatly, which leads to the wide-angle coverage ability enhancement of the low-profile antenna. A prototype operating at 2.7 GHz is fabricated and tested, demonstrating an impedance bandwidth of 15% (2.4 to 2.8 GHz). Measurement results show a 6 dB difference between the maximum and minimum gain in the upper hemisphere. With an overall antenna height of just 6 mm, all gains in the upper hemisphere exceed −3.5 dB.

A dual-band horizontally polarized omnidirectional antenna for WiFi applications is proposed in this letter, which consists of a 3-D radiation slot on a metal box and three folded patches inside. The 3-D slot is formed by connecting two trapezoid slots at top and bottom of the box with a rectangle slot at the vertical side. Then, the radiation slot is excited by a folded patch connected to the feed line and produces two resonances at 2.45 and 5.5 GHz. With the help of two parasitic patches beside the excited patch, the higher frequency band is broadened. Measured results show that the antenna has two 10 dB return loss operating bandwidths of 5.32% and 20.56%. Moreover, the measured out-of-roundness for the horizontal radiation pattern is less than 2.4 dB in lower frequency band and that of higher frequency band is less than 5.3 dB. Besides, the antenna maintains a compact size of only 22 mm × 10 mm × 25 mm (0.18 λ ₀ × 0.08 λ ₀ × 0.20 λ ₀ , where λ ₀ is the wavelength of the lowest operating frequency), with the gain about 2 dBi and the cross-polarization ratio greater than 20 dB in the entire band.

A wideband traveling-wave circularly polarized (CP) antenna printed on single-layer PCB for Millimeter-Wave (MM-Wave) applications is presented in this communication. The proposed antenna radiates the CP wave on the basis of the principle similar to the classical endfire-mode helical antenna. The proposed antenna is terminated with an absorber to realize traveling-wave radiation. The traveling-wave working mechanism causes the proposed antenna to have a frequency scanning function and higher stability compared with resonant antennas. Curved microstrip transmission lines are adopted as the CP radiation elements; the whole array antenna is etched on a single-layer substrate. A prototype operating at 30 GHz is fabricated and measured. The radiation beam of the proposed antenna scans from −14.5° (28 GHz) to +22.5° (34 GHz), the axial ratios are lower than 3 dB, and the measured gains show a maximum value of 21.9 dBi at 33 GHz and a minimum value of 20.3 dBi at 28 GHz. The measured |S11| and |S21| are lower than -10 and -16 dB, respectively, in the frequencies mentioned above.

This paper presents the design of dual circularly polarized (CP) series-fed arrays based on Sequential rotation (SR) technique with uniform radiation elements. The radiation elements and feeding network used in the array are uniform, which leads to the possibility of dual-CP radiation by series-fed SR arrays. Meanwhile, the elements radiate unequal powers due to this arrangement. The relationship between the axial ratio (AR) and four key parameters of the array is derived and thoroughly discussed. Good polarization purity and port isolation can be realized by optimizing these parameters. A dual-CP array working at 10 GHz is designed with the help of the analysis. Experimental results show that the proposed antenna has good properties.