Liwei Song

Creases in origami reflectarray antennas (ORAs) impose layout exclusion zones that invalidate conventional shaped beam synthesis, assuming continuous periodic apertures. A crease-compatible shaped beam synthesis approach is presented, in which crease-intersecting elements are treated as constrained reflectors by removing only their patches while retaining a continuous ground plane, thereby translating geometric restrictions into explicit amplitude/phase constraints. These constraints are incorporated into a modified alternating projection method (MAPM) via an iteration-updated ternary state matrix and a revised inverse projector, where the amplitudes of internal elements are kept prescribed, and only their phases are iteratively optimized. A 15 GHz hexagonal twist ORA using triangular-ring unit cells is designed to generate a sector beam in the xoz plane and a pencil beam in the yoz plane. Full-wave simulations demonstrate a peak gain of 26.4 dBi with sidelobe levels below −16.1 dB, validating the proposed beam shaping synthesis with crease constraints for ORAs.

An ultra-wide pass-band and dual-polarized frequency selective surface for K-Ka frequency band is presented. The characteristics of wide passband, angular stability, and fast roll-offs are realized by using LC resonant structures and multi-layer coupling. The whole structure of the frequency selective surface cell is symmetrical, realizing TE and TM polarization. A prototype of the proposed FSS is manufactured and measured. The size of the prototype is 123.6 mm×123.6 mm×2.961 mm. The measured results have a good agreement with the simulated ones. The measured passband is from 18.3GHz to 37.2 GHz (K-Ka frequency band), of which the relative bandwidth is 68.1%. Moreover, the passband has little change within the incidence angle ±40° for both TE and TM polarization. Therefore, the FSS can be widely used in the communication system.

The presence of creases in origami reflectarray antennas (ORAs) significantly impacts antenna layout, and traditional method of removing intersecting elements affected by creases fail to achieve desirable electromagnetic performance. This letter proposes a layout design method for ORAs that avoids creases by configuring each panel layout individually. For intersecting elements, we adjust their positions to prevent intersecting with creases. Layout optimization models are established on each panel, using the displacement values of the intersecting elements as variables. The objective of the optimization is to minimize the sum of the squares of these displacement values. Constraints ensure that the repositioned elements do not intersect with creases or overlap with adjacent elements. Using a Flasher-configured ORA with triangular ring elements as an example, the proposed method improves electromagnetic performance compared to traditional methods. A 1.2m × 1m Flasher- configured ORA prototype was designed and fabricated. Measured results demonstrate that the radiation patterns closely match the design values, with a gain of 36.64 dB at 15 GHz and sidelobes below -20 dBi on the two principal planes.

In this paper, two new methods are proposed for miniaturizing planar ultra-wideband horizontally-polarized omnidirectional Vivaldi antenna arrays. In the first method, the order of a power divider is decreased by means of feeding two neighboring Vivaldi antenna elements in series as a sub-array, or termed as a double-Vivaldi antenna element and thus the layout area required for a feeding network is reduced. Therefore, the layout problem of a conventional circular Vivaldi antenna array with a confined size is solved. Meanwhile, non-uniform elements with different taper rates are used to solve the in-band peak gain variation that is caused by a disc monopole mode. In this way, a non-uniform series-fed double-Vivaldi antenna array is presented. In the second method, a folded loop structure is introduced for an electrical size reduction of the aforementioned array. As a result, a lower resonant frequency is obtained. Measured results show that the final design has advantages of a large operating bandwidth, a small footprint of π × (0.284λ _max ) ² and a high gain. Besides, a clear design flowchart is given.

The digital model of airborne frequency selective surface radomes (AFSSRs) is the basis of design, simulation analysis, manufacturing, and other related research on AFSSRs. This paper proposes a rapid modeling method for AFSSRs based on dynamic customizable primitives. Firstly, a layered digital model construction scheme for AFSSRs is presented based on the typical radome wall structure. Then, according to the characteristics of various surface configurations and the complex wireframe information of AFSSRs, the dynamic primitives are raised to express the boundary and contour information of all kinds of radomes. Focusing on the undevelopable characteristics of the aerodynamic shape surface of the AFSSR, the arrangement solution and mapping method for frequency-selective elements on undevelopable surfaces are proposed. Furthermore, the implementation logic of this method for the creation of each layer model and the assembly of the whole machine model is introduced. Finally, a rapid modeling system (RMS) is established based on this method, enabling the automated creation of digital models of AFSSRs. Utilizing this system resulted in modeling time savings ranging from 20% to 97.5% compared to traditional methods, which verifies the feasibility and effectiveness of this method.

The digital model of airborne frequency selective surface radomes (AFSSRs) is the basis of design, simulation analysis, manufacturing, and other related research of AFSSRs. This paper proposes a rapid modeling method of AFSSRs based on dynamic customizable primitives. Firstly, a layered digital model construction scheme of AFSSR is presented based on the typical radome wall structure. Then, according to the characteristics of various surface configurations and complex wireframe information of AFSSRs, the dynamic primitives are raised to express the boundary and contour information of all kinds of radomes. Focusing on the undevelopable characteristics of the aero-dynamic shape surface of the AFSSR, the arrangement solution and mapping method for frequency selective elements on undevelopable surfaces are proposed. Furthermore, the imple-mentation logic of this method on the creation of each layer model and the assembly of the whole machine model is introduced. Finally, according to this method, a rapid modeling system (RMS) is established, and the modeling effect and efficiency of the RMS are demonstrated and compared, which verifies the feasibility and effectiveness of this method.

This work presents a quasi-precise interval analysis (IA) method for radome tolerance analysis, which tackles the precise interval prediction of radome transmission coefficient with complex expressions. Through traversal of errors and interpolation with incident and polarization angles, the precise transmission coefficient interval can be obtained, and then combined with the real-imaginary-parts-based IA (IA-RI) method and amplitude-phase-based IA (IA-AP) method for electromagnetic performance prediction. The proposed method is precise in the context of the present complex interval description method. Results compared with the currently best analytical AP method validate the effectiveness of the proposed method. The interpolation-based AP method yields the narrowest EM performance intervals, with 46%-76% width reduction over the analytical one. The interpolation-based RI method reaches a better balance between precision and efficiency, with 20%-54% width reduction and more than 99.9% time reduction.

A compact third-order filtering antenna array with high gain and two controllable radiation nulls is proposed. The antenna consists of one narrow patch in the center fed by the coaxial port and four wide patches placed around it. Four short-end stub-loaded resonators are capacitively coupled between the center patch and the outer patches, which makes the radiated E-fields of the center patch and the outer patches in-phase at the center frequency of the passband to realize the high gain and out-of-phase at the low and high stopbands to introduce a pair of radiation nulls. The working principle of the filtering antenna array can be explained by the coupled-resonator network. Finally, a filtering antenna array centered at 3.5 GHz with a fractional bandwidth of 4.26%, a high maximum gain of 12.2 dBi, high out-of-band selectivity, and wide stopband is designed, fabricated, and measured.

In this paper, a dual-band frequency selective rasorber(FSR) is proposed based on a composite absorption structure. The FSR is a three-tier structure composed of lossy layer I, lossy layer II and a dual-band frequency selective surface (FSS). The lossy layer I is composed of a lossy cross-shaped structure in which, dual-passband resonators are added and constructed by parallel interdigital capacitors and meandering strip inductors(PLC). The lossy layer II is composed of a hybrid circular strip resonator loaded with lossy elements. FSS is implemented in two Jerusalem slots. By combining the lossy layers I and II as a composite lossy structure, the absorption bands of lossy layers I and II are successfully connected in the frequency response, and the bandwidth of S ₁₁ under -10dB is extended from 3.1 to 20.6GHz. The proposed FSR integrate dual-band, dual-polarized, and broadband absorption performance simultaneously. Finally, a prototype of the composite FSR is fabricated to validate the simulated results.

A low-profile, wideband, and high-gain antenna array, based on a novel double-H-shaped slot microstrip patch radiating element and robust against high temperature variations, is proposed in this work. The antenna element was designed to operate in the frequency range between 12 GHz and 18.25 GHz, with a 41.3% fractional bandwidth (FBW) and an obtained peak gain equal to 10.2 dBi. The planar array, characterized by a feed network with a flexible 1 to 16 power divider, comprised 4 × 4 antenna elements and generated a pattern with a peak gain of 19.1 dBi at 15.5 GHz. An antenna array prototype was fabricated, and the measurements showed good agreement with the numerical simulations as the manufactured antenna operated in the range of 11.4–17 GHz, with a 39.4% FBW, and the peak gain at 15.5 GHz was 18.7 dBi. The high-temperature simulated and experimental results, performed in a temperature chamber, demonstrated that the array performance was stable in a wide temperature range, from −50 °C to 150 °C.