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A novel low-profile grooved-dielectric choke ring with dual-band surface impedance resonance is proposed and experimentally demonstrated. The proposed structure is designed by engineering the surface impedance of a dielectric-based choke ring to introduce two resonant frequencies around the global navigation satellite system (GNSS) bands of L2 (1227.60 MHz) and L1 (1575.42 MHz). This provides capacitive surface impedances around both bands simultaneously, which is required for efficient surface wave suppression for higher multipath rejection performance. To demonstrate the proposed principle of surface impedance engineering, an in-house choke ring prototype of the proposed design is tested with the widely used Dorne and Margolin antenna. A high multipath rejection in both GNSS bands is experimentally confirmed with comparable performances to an otherwise bulky, heavy, and expensive conventional metallic choke ring.

This paper proposes a robust option for developing a new class of efficient and cheap antenna array based on patch array fed by substrate-integrated waveguide (SIW) through slot apertures for wireless backhauling applications. It consists in performing the feed network in SIW and the radiating structure in microstrip technology. The microstrip lines are coupled to the slots on the top wall of the SIW. Hence, it is demonstrated that the best alternative of the costly, heavy, and bulky rectangular waveguide feeder is SIW, which provides miniaturization, cost reductions, performance enhancements, and easy integration with patch array antennas. The experimental prototype presented in this paper demonstrates the efficiency of the design method and the feasibility of creating low-cost moderate-bandwidth millimeter-wave planar $8\times 8$ patch antenna array configurations in two stacked substrates to get ultracompact antenna module. The principle of achieving such high-quality antenna array is presented in detail along with experimental verification of theoretical results to validate the design procedure and demonstration of the feasibility of implementing the array by means of relatively inexpensive compact structures. The maximum gain is around 23 dBi at 22.4 GHz, the measured impedance bandwidth is 5%, and the efficiency is around 70%.

This paper presents a global navigation satellite system (GNSS) circularly polarized ceramic patch antenna using the Yagi-Uda theory to generate a null in the right hand circular (RHC) gain pattern at the horizon and around all azimuth angles to mitigate ground-based interference. The study shows that you can control the nulling elevation angle by changing the spacing of the directors used in this Yagi structure. The optimized results show an important attenuation of the RHC gain at an elevation of 15 degrees. At this elevation the RHC gain is 35 dB down from the max gain which is close to 8 dBic at zenith. The proposed AJ3000 antenna is an efficient and low-cost solution to reduce the impact of intentional and unintentional interference in the higher GNSS band for timing applications.

A novel low-profile dual-band tunable artificial magnetic conductor (AMC) structure based on the choke ring is presented in this paper. The structure is tuned to the Global Navigation Satellite System (GNSS) frequencies of L2 (1227.60 MHz) and L1 (1575.42 MHz). Using full-wave simulations for the Dorne & Margolin (DM) antenna mounted on the AMC structure, it is demonstrated that the proposed dual-band structure provides good multipath performance at both L2 and L1. Compared to the conventional choke ring, the novel design provides a 52% reduction in height and a 26% reduction in diameter.

In this study, a 60 GHz optically transparent microstrip (OTM) patch antenna array is designed, fabricated and measured. Gold meshes are implemented for the two layers of the antenna. A numerical parametric study on the positioning of the two meshed layers is performed to give design considerations and optimise both the electromagnetic and optical performances of OTM antennas at 60 GHz band. The simulation and measured results of the OTM antenna with a theoretical maximum transparency up to 74.6% are compared with a light reflecting reference antenna. Both antennas have similar reflection coefficients and radiating performances. This study provides practical design rules to fabricate high gain OTM antennas with performances similar to those of standard topologies at 60 GHz band, with the addition of high optical transparency.

The performance of multiple-input-multiple-output (MIMO) system operating at the 60 GHz band is investigated based on experimental data in a real underground mine gallery. However, the millimeter wave (mmW) channels face some challenges such as high propagation loss. In order to overcome this issue, a planar microstrip antenna array has been designed, and fabricated. Moreover, the effect of miners' activity in the vicinity of the short-range wireless link is studied. Statistical parameters of the propagation channel, such as RMS delay spread, path loss, K-factor, channel correlation and capacity are extracted and analyzed. Results suggest that miners presence substantially affects both received power and time dispersion parameters and should therefore be considered when developing underground mine wireless networks in the unlicensed 60-GHz band.

This paper presents a feasibility study on an optically transparent planar monopole lozenge antenna at the 60-GHz industrial-scientific-medical (ISM) band. The feeding of this antenna is composed of a 50- $\Omega$ meshed coplanar waveguide. The size of the proposed antenna is around 2.3 $\,\times\,$ 2.3 mm $^{2}$ . The transparent and conductive material used to fabricate the proposed antenna is made of a gold grid layer deposited on a 0.2-mm-thick fused silica 7980 Corning substrate. The theoretical transparency equals 83% with a sheet resistance of 0.44 $\Omega$ /sq. The simulated and measured results of the transparent monopole antenna are compared to a nontransparent (but identical) antenna. It was found that both antennas have the same performances in terms of bandwidth, radiation pattern, and gain. The measurements show the same behavior for transparent and nontransparent antennas. These results confirm the absence of ohmic and skin depth losses in the gold grid layer at 60-GHz ISM bands and provide the possibility of implementing transparent antennas with performances absolutely identical to the nontransparent ones, with the advantage of a soft visual impact.

This paper presents two solutions to improve the front to back ratio (FBR) of the VeraPhase® (VP6000) antenna. A compact and light disk structure and a ground plane with absorber layer located under the antenna were designed and optimized in the 3D RF simulator WIPL-D in order to reduce the FBR without impacting the other performances of the antenna. The optimized results show great improvement of the FBR at all frequencies from 2.5 dB up to 7.3 dB without reducing the gain in the upper hemisphere of the antenna. The proposed solution are both efficient and low cost solutions to optimize the FBR of the VP6000.

Meshed silver/titanium films, deposited on a 1737 Corning glass substrate by radiofrequency (r.f.) magnetron sputtering and etched by wet process, have been studied. Sputtering parameters have been specifically optimized for thick Ag layer deposition (> 3 μm) and are discussed. An original excimer laser etching process is used for removing the resist for making the prototypes. Simple sheet resistance and optical transparency computings have been used for the theoretical study. A good agreement is obtained with the experimental results. Transparent and conducting samples have been realized with optical transmittances and sheet resistances ranging from 71% to 81% and from 0.023 Ω/□ to 1.03 Ω/□, respectively. Hence we demonstrate the independence between optical transparency and sheet resistance for this material AgGL (Ag Grid Layer). The relevance of the mesh structure has been highlighted by the achievement of samples with high level of transparencies and ultra-low sheet resistances.

This paper deals with the evolutionary research and development of an antenna intended to have excellent suppression of unwanted left circular polarization, excellent phase center stability and coverage of all of the present and proposed GNSS frequency bands while still having high radiation efficiency and a compact size. A series of innovative antenna structures, built in software, were analyzed and optimized with an EM simulation software package. Physical prototypes were constructed and measured and the excellent performance of the antennas was demonstrated. Tallysman has undertaken the commercial development, measurement processes and manufacturing of the antenna. An optimization of the radiation element has been conducted, a Low Noise Amplifier (LNA) has been designed and implemented and the mechanical design has been modified to fit the commercial production requirements. Detailed performances are presented for the TallysmanVeraphase GNSS antenna.

This letter presents a dual-slot antenna etched on a substrate integrated waveguide. This antenna is designed, fabricated, and measured to operate at X-band. It uses two unequal slots in order to increase the bandwidth. The measured results show a bandwidth of 8.5%, which is twice that of the standard dual-slot antennas. Attractive features including low cost, compact size, and planar form make this antenna easy to integrate within microwave planar circuits.

The purpose of this paper is to propose a new high gain RF identification (RFID) tag antenna on 915 MHz band for the underground localization applications. The proprieties of the new RFID antenna are investigated in terms of implementation and performance; the study focuses on the substrate of the printed microstrip RFID antenna to increase the gain and then ensures large reading range. Several operations have been applied to the original microstrip patch antenna to establish impedance matching and to achieve high gain RFID tag antenna. In addition, a miniaturization of the antenna is achieved.

This letter presents a feasibility study of a large optically transparent broadband antenna for urban radio cellular networks. The proposed H-shaped slot antenna, which is well suited for antenna arrays, is made of three transparent and conductive layers printed on three glass substrates separated by two air gaps. The size of the antenna is close to 300×300×20 mm3. The transparent and conductive coatings used to fabricate the antenna are made of a silver grid layer (AgGL) deposited on one side of each 1.1-mm-thick 1737 Corning glass substrate. The theoretical optical transparency of the multilayer antenna ranges between 51.6% and 70.7% over the whole visible light spectrum. The measured electromagnetic performance of the transparent H-shaped slot antenna has been compared to that of a nontransparent (but geometrically identical) simulated antenna. The results show a similar behavior and performance in terms of bandwidth, radiation pattern, and gain. This confirms the restriction of the ohmic loss and skin depth loss from the AgGL material. These also provide the ability to implement large transparent antennas with performance identical to that of nontransparent ones, and most importantly with the advantage of a soft visual impact on urban environment.

In this paper, a planar 60 GHz CPW-fed monopole lozange antenna for switched-beam antenna array application is presented and investigated. The proposed radiating element is a 1.1 mm × 1.1 mm square fed by a CPW feed line. This structure can be an advantage for low coupling and cross-polarization levels in antenna arrays. The simulation results show a return loss less than −10 dB on the whole ISM 60 GHz. In addition, gain is stable.

International audience

This study presents a new millimetre-wave printed antenna array fed by a rectangular waveguide. This compact, light and low-cost antenna, composed of a large number of linear subarrays of patches fed by a waveguide drilled in the ground support, is well suited to urban microwave links for cellular base stations. Measurements show a peak gain of 30 dBi with an efficiency of 69%.

A technology based on a meshed silver/titanium bilayer printed on glass substrate is briefly presented. A sheet resistance equal to 0.054 /sq with 81.3 of optical transparency is obtained. The performances of a monopole antenna made from such a material have been investigated. The measured S 11 and gain of the transparent antenna are compared with those of an antenna fabricated from a reflective silver/titanium film, and stand for reference. The transparent antenna provides radiation efficiency better than 85%.