Low-profile Substrate Integrated Waveguide Research Articles

A low-profile SIW multi-beam antenna array fed by a compact two-layer 6 × 6 BFN

Abstract This paper presents a low-profile six-beam antenna implemented by a compact two-layer 6 × 6 beamforming network (BFN) and a 6 × 2 slot antenna in substrate integrated waveguide (SIW) technology. The main components of the proposed 6 × 6 BFN are 3 × 3 multi-aperture couplers, interlayer hybrid couplers, and several phase shifters which are embedded on two microwave substrates. The proposed antenna has been designed, simulated, and fabricated for the frequency range of 28–32 GHz. The size of this antenna is 82 × 31.8 × 0.787 mm3, which can be a suitable choice for 5G applications due to its compact dimensions compared to similar works. Prototype testing shows that the proposed structure presents a stable beamforming performance both in simulation and measurement with good agreement. The antenna generates six radiation beams in directions ±9°, ±30°, and ±54° with good return losses and isolations.

Wideband Low-Profile SIW Cavity-Backed Circularly Polarized Antenna With High-Gain and Conical-Beam Radiation

A low-profile substrate-integrated waveguide (SIW) cavity-based antenna with conical-beam circularly polarized (CP) radiation is presented. Conical-beam CP radiation is obtained by the combination of a radial current source and a loop current source, which are produced by a shorted monopole patch and an annular array, respectively. The proposed annular array configuration is designed by combining multiple identical customized parasitic patch elements arranged around the monopole. Phase compensatory lines and shorted annular ring slots are introduced in the array to tune phase difference of two current sources and to generate in-phase currents on the elements, respectively. All antenna elements are simultaneously excited within a center-fed SIW cavity. In order to fully picture the operating mechanism, we analyze the wide impedance and axial-ratio (AR) bandwidths based on an equivalent circuit model and an electromagnetic theory. Then, parametric studies are carried out for a detailed design illustration. To verify the design, a prototype has been fabricated and measured, which shows a stable conical-beam radiation and good performance including: a low profile of $0.062\lambda _{0}$ , a 10 dB impedance bandwidth of 20.4%, a 3 dB AR bandwidth of 17%, a maximum gain of 8.25 dBic, and an advantage of large ground compatibility.

Low profile SIW slot antenna with wide beam‐width radiation pattern

A linearly polarised antenna with wide beam-width is proposed. This antenna is based on substrate integrated waveguide (SIW) cavity. The half-power beam-width is about 145° in the E-plane, and 140° in the H-plane. This proposed antenna has a low profile of 0.03λ0 (λ0 denotes to the space wavelength corresponding to the operating frequency centre) and a compact size of 0.31λ0 × 0.31λ0, which is very suitable for modern communication systems. The maximum gain is about 6 dBi, and the radiation efficiency is about 90% at the working frequency band. The cross polarisation is very small.

Substrate-Integrated-Waveguide E-Plane 3-dB Power-Divider/Combiner Based on Resistive Layers

Several different microwave circuits, including beamforming networks and balanced amplifiers, make use of 3-dB power dividers and combiners. A well-known architecture able to work over large bandwidths, a critical request for many applications, is based on E-plane three-port waveguide structures, where a lossy element is added to overcome the inherently poor isolation given by lossless three-port junctions. While a standard implementation based on normal rectangular waveguides often results in large and heavy structures, an implementation based on substrate-integrated-waveguide (SIW) technology offers advantages in terms of compactness, weight reduction, cost minimization, and integration possibilities with active stages. This paper presents the design, fabrication, and characterization of two SIW E-plane 3-dB power divider/combiners where the lossy element is realized using a resistive layer. The prototypes cover the entire X-band from 8 to 12 GHz, and the resistive layers are realized according to two different manufacturing techniques to investigate the potentials of both approaches. The optimization of the resistive layer geometry and resistivity, a critical aspect for low-profile SIW circuits, is discussed in detail. In particular, an analytical formula is derived, which allows to determine the optimum values for the resistive layers' principal parameters, namely the length and resistivity, without the use of full-wave numerical solvers.

Wideband Circularly Polarized Substrate Integrated Waveguide Endfire Antenna System With High Gain

A K-band endfire substrate integrated waveguide (SIW) circularly polarized (CP) antenna system on a single-layer printed-circuit board is proposed. A high-gain SIW H-plane horn and a Vivaldi antenna are developed to produce two orthogonal polarizations in the plane of the substrate. They are combined with a low-profile SIW 3-dB coupler to provide identical feeding amplitudes with 90° phase difference. The performance of the CP antenna system is demonstrated over the 23-27-GHz frequency range by comparing simulations and measurements in terms of gain, axial ratio, radiation pattern, and return loss. The results show that the proposed antenna system operates with a wideband 3-dB axial ratio from 24.25 to 26.5 GHz and a high and uniform gain of almost 8 dB. Measured results are found in good agreement with simulations.

Conformal SIW H-Plane Horn Antenna on a Conducting Cylinder

This letter presents a conformal wide-band substrate integrated waveguide (SIW) H-plane horn antenna mounted on a large conducting cylinder. The effect of a curved low-profile SIW H-plane horn is examined when it is mounted on a conducting cylinder of varying radius. In order to compensate the deterioration of the voltage standing wave ratio (VSWR) of the H-plane horn antenna, two air slots along the sides of the flare part of the antenna are cut. With the utilization of the slots, the matching between the feed line and the horn antenna is improved and the working frequency bandwidth is broadened simultaneously. Measured VSWR of the fabricated antenna is below 2.5 from 6.1 GHz to 19 GHz. The antenna also exhibits stable radiation beam over the same frequency range. It is observed that measured results agree well with simulated ones.

군위성 송수신기용 기존 금속 도파관을 대체하는 DNG형 기판적층 도파관 공진기의 설계

A new and significantly small guided and resonant structure is suggested to take over bulky metallic hollow waveguides used in military satellite transceivers. Below Ku-band, the conventional waveguides resulting in quite heavy transceivers will be replaced by the low profile SIW(substrate integrated waveguide) structures that are distinguished from the others in that the suggested ones have much lower cut-off frequencies by the circuital configuration of DNG(dobule negative) constitutive parameters and become even smaller than the other SIWs. The design scheme is validated by the circuit and full-wave simulations from the guided, resonant, and coupled structures. Besides, a bandpass filter as the suggested coupled structure is fabricated with a cheap substrate in a low-budget fabrication process and its frequency response is measured as verification of the purpose of the design.