Abstract-A novel wideband substrate integrated waveguide (SIW) antenna topology, consisting of coupled half-mode and quarter-mode SIW resonant cavities, is proposed for operation in the 60 GHz band. This innovative topology combines a considerable bandwidth enhancement and a low form factor with compatibility with low-cost PCB manufacturing processes, making it excellently suited for next generation, high data rate wireless applications. Moreover, exploiting SIW technology, a high antenna-platform isolation is obtained, enabling dense integration with active electronics without harmful coupling. The computer-aided design process yields an antenna that covers the entire [57-64] GHz IEEE 802.11ad band with a measured fractional impedance bandwidth of 11.7% (7 GHz). The measured maximum gain and radiation efficiency of the prototype are larger than 5.1 dBi and 65%, respectively, within the entire impedance bandwidth.Index Terms-Coupled resonators, substrate integrated waveguide (SIW) antenna, half-mode SIW (HMSIW), quartermode SIW (QMSIW), bandwidth enhancement, wideband, 60 GHz. I. INTRODUCTIONn recent years, an increasing demand for broadband multimedia applications has appeared, which forces the capacity of wireless networks to increase continuously. 5G mobile communication is an excellent example of this trend, as extremely high data rates need to be offered to the end user. To this end, novel wideband antenna topologies need to be developed, exhibiting a limited footprint while being implemented through cost-efficient manufacturing, as required for integration into user equipment, such as handsets.As the spectrum up to 6 GHz is becoming ever more crowded, the [57-64] GHz IEEE 802.11ad band is the ideal candidate to meet the requirements of 5G mobile communication systems, both in terms of bandwidth and number of interconnected devices. This globally available and T. Deckmyn, D. Vande Ginste and H. Rogier are with the Department of Information Technology, IDLab, Ghent University -imec, Technologiepark 15, 9052 Ghent, dries.vande.ginste@intec.ugent.be; hendrik.rogier@intec.ugent.be).S. Agneessens is with the Department of Information Technology, IDLab, Ghent University -imec, 9052 Ghent, Belgium, and also with the Centre for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, 9052 Ghent, Belgium. He is currently an FWO unlicensed band offers 7 GHz of frequency spectrum for wideband communication. The high atmospheric attenuation, caused by the absorption peak of oxygen atoms, makes the conditions ideal for short range, low interference, and highly secure communication between many devices sharing the same spectrum [1]- [2].Nowadays, a breakthrough of the very promising Substrate Integrated Waveguide (SIW) technology is apparent in the millimeter wave research field [3]. Recent trends and applications include antennas, filters and couplers for RF frontends [4], beam steering [5] and MIMO systems [6]. The heightened interest in SIW technology for millimeter wave applications can be att...

A novel dual-band substrate integrated waveguide (SIW) antenna array topology is proposed for operation in the 28 GHz and 38 GHz frequency bands. Four miniaturized quartermode SIW (QMSIW) cavities are tightly coupled, causing mode bifurcation and yielding an antenna topology with four distinct resonance frequencies. A pair of resonances is assigned to both the 28 GHz and 38 GHz band, achieving wideband operation in both frequency ranges. Moreover, owing to the exploited miniaturization technique, an extremely compact array topology is obtained, facilitating easy and straightforward integration. The computer-aided design process yields a four-element antenna array that entirely covers the 28 GHz band (27.5-29.5 GHz) and 38 GHz band (37.0-38.6 GHz) with a measured impedance bandwidth of 3.65 GHz and 2.19 GHz, respectively. A measured broadside gain of 10.1 dBi, a radiation efficiency of 75.75 % and a 3 dB beamwidth of 25° are achieved in the 28 GHz band. Moreover, in the 38 GHz band the measured broadside gain amounts to 10.2 dBi, a radiation efficiency of 70.65 % is achieved and the 3 dB beamwidth is 20°.

A dual semi-circular microstrip patch antenna implemented on a biodegradable substrate is presented for operation in the [863-873]-MHz and [2.4-2.5]-GHz frequency bands. To cover these frequency bands, two semi-circular patches are compactly integrated onto a biodegradable cork tile, commonly found as support in laminate flooring, serving as a substrate. Thereby, the antenna tile may be seamlessly embedded as a sublayer of the floor structure. A higher-order mode is generated by applying via pins in the antenna topology, to produce a conical radiation pattern with a null at broadside and sectoral coverage in the vertical plane. As such, the concealed-floor antenna covers all azimuth angles of arrival in smart houses. The antenna performance is fully validated, also when the tile is covered by different PVC sheets. Owing to the supplementary design margins, the antenna impedance bandwidth remains covered. Moreover, the radiation patterns are measured in various elevation planes. In stand-alone conditions, a radiation efficiency and a maximum gain of 74.3 % and 5.8 dBi at 2.45 GHz and 48.1 % and 2 dBi at 868 MHz are obtained. Its omni-directional coverage in the horizontal plane, stable performance on the inhomogeneous and biocompatible cork substrate and for various inhomogeneous superstrates and its low-profile integration make the proposed antenna an excellent candidate for smart floors and smart houses.

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For the design and production of reliable devices applied in wearable components, characterization of the electromagnetic properties of materials is of paramount importance. Therefore, we propose a novel approach, based on a resonance-perturbation method, which compares simulations and performed measurements. An inset-fed patch antenna with a resonance frequency in the vicinity of the 2.45-GHz Industrial, Scientific, and Medical band enables us to quickly estimate the characteristics of a given material sample. In a first step, the two frequencies for which the simulated return loss of the fixture crosses a defined threshold are modeled as polynomial functions of the relative permittivity and loss tangent of the material under test. Then, the electromagnetic properties of the material are obtained by comparing the modeled and measured frequencies. The electromagnetic properties of several textile materials of interest are determined with this method. It is shown that the proposed technique is fast, precise, and nondestructive. Owing to this, it is suitable for integration into an assembly line, where substrate samples are straightforwardly characterized before being used for the manufacturing of actual antennas.