The Prototype of a Wideband Ku-Band Conical Corrugated Horn Antenna with 3-D Printing Technology

This study is about the design and production of a conical corrugated horn antenna used to feed reflector antennas in satellite communication (direct broadcast satellite-DBS) systems. The antenna designed with CST Microwave Studio program operates within wideband of 10.5-18.5 GHz at Ku-band. The prototype is realized with new generation 3D printing technology and conductive paint coating method, which makes the antenna lightweight and provides low cost and faster production. According to measurement results, the antenna has return loss almost better than 20 dB, gain value of minimum 14.5 dBi and sidelobe level of -18 dB at most within 1.76:1 frequency bandwidth. Antenna is observed to have a gain loss of at most 1.5-2 dB within the band as compared to the same antenna with high conductivity metal, which needs higher cost and production time for the manufacturing

Measuring Characteristic Shrinkage Variability Due to Metal Loading Effects in Low Temperature Co-Fired Ceramic Using Image Processing

Low temperature co-fired ceramic (LTCC) has many benefits when it comes to electronic packaging due to the low dielectric loss, reliability in extreme environments, and high breakdown voltage. Though the ceramic has a lot of benefits it is not widely used due to the high cost and complexities associated with manufacturing. One of these issues with manufacturing is compensating for the shrinkage of the ceramic, this is accomplished by using an expansion factor, creating the “green” or manufactured design. This expansion factor is approximated through knowledge of the ceramic factors such as the metal loading, layers of ceramic tape, firing profile, lamination pressures, etc. While this expansion factor method has been studied and equations have been derived for compensation for the shrinkage, there is little evidence that the equations correctly compensate for the complexities of the design. Due to the lack of understanding of how different design parameters play a role in the shrinkage of the panel, this thesis will look to address the fundamental issue of measuring the shrinkage effects due to metal loading using a shrinkage characterization method called shrinkage field mapping. Due to the increased measurements needed for shrinkage field mapping, image processing is used to extract dimensions without dramatically increasing measurement time for the High-Density Electronics Center LTCC process. With the change in the shrinkage measurements, a 0.07-0.25% characteristic shrinkage difference can be measured from changing the volume of metal inside by 1.22mm3 in a DuPont 9k7 50mm x 50mm panel. These measurements were confirmed by three different fabrication experiments

Design and Analysis of Microwave Devices Based on Gap Waveguide Technology

Among state-of-the-art guiding structures, the Ridge Gap Waveguide (RGW) is a promising technology, as it minimizes the losses in high-frequency applications and supports wide operating bandwidth. There is another form of the guiding structures that utilize the idea of the Artificial Magnetic Conductor (AMC) surfaces such as Groove Gap Waveguide (GGWG). It has the same advantages as the RGW in terms of losses, and immunity to leakages without the need for electrical contacts, but with different dispersion characteristics. The RGW supports a quasi-TEM mode while the GGWG supports TE modes as it's a different form of the rectangular waveguide. Therefore, GGWG has high power capability comparable to the standard waveguides. As currently, interest is increasing of millimeter wave and microwave applications, the RGW and GGWG are excellent candidates for these applications due to their low loss. It is quite essential to develop microwave components with superior electrical characteristics for such applications. The anisotropic materials have useful physical properties that can benefit the microwave devices, due to their enormous advantages such as high stability and wide bandwidth in the millimeter wave band. Ferrite is an example of such anisotropic materials. Their properties can be deployed to improve the performance of the millimeter microwave devices in terms of higher stability, wider band, and high power handling. Taking advantages of the above characteristics, the research work in this thesis is focusing on their use for microwave and millimeter wave frequencies. The presented devices are responsible for the feeding of the antenna systems. Moreover, they can be deployed in different applications such as antenna beamforming. In this thesis, the differential phase shifters and the orthomode transducers (OMTs) are realized by different technologies that are suitable for both of the microwave and the millimeter wave bands that serve different applications of the wireless communication systems. The research work done can also be summarized in two parts. The first part starts with the study and investigation of the ferrite material properties and their role in the microwave devices. Then, later providing a new accurate model with mathematical formulas for the differential ferrite phase shifter. Moreover, a new design methodology for those phase shifters is presented. Later, the ferrite is applied in the conventional waveguide, Substrate Integrated Waveguide (SIW), and RGW technologies. In the second part, study, design, and analysis of different types of the orthomode transducers are presented. They are devices responsible for combining and separation of two orthogonal polarizations. The presented OMTs has a compact size with excellent performance. Several OMT types are considered such as the one-fold symmetry, asymmetric, and two-fold symmetry. The first mentioned two OMTs are realized by deploying the waveguide technology, while the two-fold symmetry OMT is based on the GGWG technology. It has the ability to design a feeding network for an array of antennas based on the GGWG technology. Moreover, this OMT is fabricated using 3D printed technology that uses the carbonated plastic material, in which two copper layers are covering all the structure surfaces by electroplating. This fabrication is a new promising technology that is not expensive, lightweight and less complex than traditional machining. However, there are some concerns about power handling and high temperature withstanding. Such problems might have a solution in the future with a more accurate 3D metallic printers

Stereolithography-Based Antennas for Satellite Communications in Ka-Band

International audienceThis paper illustrates the role of additive manufacturing (AM) as enabling technology to realize high-performance low-cost antennas for Ka-band applications. In addition to the inherent electromagnetic challenges implicit in the conception of such complex devices, this paper also points out the stringent limitations that appear when opting for classical fabrication techniques, based on assembled split-block models. AM emerges in this context as a change of paradigm, allowing mono-lithic fabrication and design freedom, which result in substantial improvements in terms of compactness, mass, simplicity, cost, and production time. Two different antennas for Ka-band satellite communications are presented here, namely a wideband horn and a dual-band circular cavity. Both prototypes are fabricated using a stereolithographic (SLA) AM process followed by metal coating. This fabrication approach is especially well suited to the implementation of these designs, since they have internal shapes that are inaccessible to conventional machining tools. The experimental results are not only in very good agreement with the theoretical predictions but also demonstrate improvements over the performances achieved by traditional milling and assembly fabrication approaches, thereby confirming the validity and great potential of SLA for Ka-band satellite communications

Stereolithography-Based Antennas for Satellite Communications in Ka-Band

This paper illustrates the role of additive manufacturing (AM) as enabling technology to realize high-performance low-cost antennas for Ka-band applications. In addition to the inherent electromagnetic challenges implicit in the conception of such complex devices, this paper also points out the stringent limitations that appear when opting for classical fabrication techniques, based on assembled split-block models. AM emerges in this context as a change of paradigm, allowing monolithic fabrication and design freedom, which result in substantial improvements in terms of compactness, mass, simplicity, cost, and production time. Two different antennas for Ka-band satellite communications are presented here, namely a wideband horn and a dual-band circular cavity. Both prototypes are fabricated using a stereolithographic (SLA) AM process followed by metal coating. This fabrication approach is especially well suited to the implementation of these designs, since they have internal shapes that are inaccessible to conventional machining tools. The experimental results are not only in very good agreement with the theoretical predictions but also demonstrate improvements over the performances achieved by traditional milling and assembly fabrication approaches, thereby confirming the validity and great potential of SLA for Ka-band satellite communications

Antennas for low-cost Ka-band ground terminal devices

The ever-growing demand for high-speed data links together with the increasing congestion in the traditional microwave spectrum are pushing for the exploitation of higher microwave and millimeter-wave (mm-wave) frequencies, including the so-called Ka band. Major investments came along, especially in the satellite communications industry, raising the technological con-straints imposed on electronic equipment, mainly concerning performance, compactness and both reduced cost and weight. The great antenna size reduction achieved at Ka band has boosted the research towards satel-lite-on-the-move applications (SOTM), aiming the development of ground terminal antennas for both commercial and personal use. Such antennas must work simultaneously at downlink and uplink Ka bands with circular polarization and also have beam steering capabilities to keep a steady connection with the satellite. In addition, the target is also achieving a cost-effective low-profile antenna. The present thesis is focused on the design of feed antennas to be integrated in mechanical beam steering systems for the aforementioned application. Three different designs are here proposed and discussed. The first one, a wideband ridged horn antenna, was tested standalone and with a dielectric lens antenna. Once good results were achieved in both sce-narios, reducing its height would be the next goal. Thus, the second design is a cavity backed patch antenna. A comparison between both feed antennas is performed, highlighting the pros and cons of both solutions, either standalone or with the same dielectric lens antenna. Here, the first studies with a planar lens antenna are shown. Finally, the third device consists of a ridged cavity antenna with a cross-slot on its top aperture. This time, the feed was successful-ly tested with a transmitarray which allows achieving a more compact antenna system than the first one here presented. This thesis also analyzes two different manufacturing techniques, traditional milling technique and an innovative additive manufacturing (AM) technique based on metallized polymers called stereolithography (SLA). The present AM-SLA prototypes clearly illustrate the strong potential of this technology and pushes for its further assessment