Title: Antenna-in-package Solutions for Microwave and Millimeter-wave Applications (Antennes in de verpakking: oplossingen voor microgolf en millimetergolf toepassingen)
Other Titles: Antenna-in-package Solutions for Microwave and Millimeter-wave Applications
Authors: Enayati, Amin; S0197515
Issue Date: 29-Nov-2012
Abstract: In the following thesis, different technologies have been investigated to implement antenna-in-package solutions at microwave and mm-wave frequencies. This investigation is done by implementing different antenna elements and arrays in each technology, depending on the manufacturing capabilities available in each of them. The technologies investigated are: Flex-Rigid PCB, Ceramic-based PCB, Teflon-based PCB, LTCC and thin-film. Moreover, as a potential application for the antenna-in-package solutions at mm-wave frequencies, a holographic imaging system has been studied.In the 1st study, a 3D antenna-in-package solution is implemented in a Flex-rigid PCB technology. The antenna package shows a better-than-10-dB return loss at 17.2 GHz which was the design frequency. Its radiation pattern is very similar to a simple dipole and makes it very suitable for sensor network nodes. In that case the antenna-in-package solution holds the electronics inside a cubic volume of 1 cm3 and radiates to the surrounding environment by a dipole-like radiation pattern. This study shows that the proposed Flex-Rigid technology is a promising choice when the antenna-in-package solution needs to cover a geometrical object with sharp edges in a 3D manner. That is mainly because of a flexible laminate used in the layer build-up of this technology. Moreover, this technology can also be used for the mm-wave applications if a precise sensitivity analysis is done in the design phase. To study the applicability of Ceramic-based PCBs at mm-wave frequencies, a layer build-up incorporating RO4003C has been used to implement two antenna-in-package solutions. The 1st solution incorporates a printed 1x2 dipole array. The antenna return-loss and gain bandwidths show promising results for the standard 60-GHz communication band. Moreover, an aperture patch element has been implemented in the same PCB technology. Although the antenna shows an acceptable return loss, its gain behavior is not flat enough across the whole 60-GHz band. As RO4003C is a well-known material among the microwave engineers, the main goal of this study was to investigate the characteristics of this laminate at mm-wave frequencies. This study shows that RO4003C is an appropriate choice for the antenna-in-package solutions at mm-wave frequencies provided that the manufacturing inaccuracies are taken into account in the design process. Although it possesses the worst electrical performance among the technologies investigated here, it is suitable for mm-wave applications when a very simple layer build-up is needed. As a result of its simple layer build-up, the Ceramic-based technology is the cheapest one among the technologies investigated in this thesis.To achieve the minimum possible loss at mm-wave frequencies, a multi-layer asymmetric Teflon-based PCB technology has been used to implement 2 antenna-in-package solutions. In the 1st solution a Horn-like element has been designed and investigated in different array configurations. Although the Horn-like element shows a very promising return-loss behavior, its gain and radiation patterns vary drastically with frequency in the 60-GHz band. However, in terms of interconnect loss and surface-wave excitation it yields very promising characteristics. An end-fire Vivaldi-like antenna element has been designed also in the same technology. The antenna covers the whole 60-GHz frequency band both in terms of return loss and gain values. Hence, it can be used in the multi-antenna beam-forming applications not only in the 60-GHz band but also in higher-frequency bands. The main goal of this study was to investigate Teflon-based laminates at mm-wave frequencies. Although the layer build-up is complicated and expensive, it yields the best electrical performance among the other technologies investigated here. However, in terms of packaging performance and reliability, it is the worst technology among the ones investigated in this thesis, especially when several metalized vias are needed in the antenna-in-package solution. In another study, a thin-film technology incorporating high-resistivity Silicon has been used to implement a cavity-backed antenna-in-package solution. Note that the metalized cavities are hardly available in other technologies rather than thin-film technology. Hence, this technology is the best choice to implement cavity-backed antennas. The structure proposed shows the best performance in terms of similarity between the simulation and measurement results because of the very accurate technology used to implement it. Moreover, it covers the whole 60-GHz standard band both in terms of return-loss and gain bandwidths. Two 1x4 arrays were designed and fabricated based on the cavity-backed element. They both show promising results in terms of return loss and pattern shape that makes the antenna element a valuable candidate for 60-GHz applications. The thin-film technology shows the best manufacturing capability among the technologies investigated here. Moreover, it is a very promising technology for the packaging purposes because it uses the same packaging material, i. e. Silicon, as the one used for the transceiver ICs. Finally, an LTCC technology has been studied for antenna-in-package solutions at mm-wave frequencies. Two antenna elements are implemented in this LTCC technology and their performances were investigated. The 1st antenna element is a probe-fed patch, fed by a folded SIW feeding network. The antenna element has a wide return-loss bandwidth and its gain bandwidth covers the 60-GHz standard band. The 2nd antenna which is a Horn-like element has a wide bandwidth return-loss while its gain behavior is not so wideband. Despite the fact that this Horn-like antenna reduces the surface-wave excitation, its radiation pattern changes so drastically with frequency that makes its applicability limited for the 60-GHz standard band. This study shows that the LTCC technology delivers the best packaging capabilities for antenna-in-package solutions at mm-wave frequencies. Moreover, compared to the Teflon-based PCB and thin-film technologies which are on the same level of complexity, the LTCC technology is the cheapest one. The unique capability of having stacked vias in LTCC technology makes it the best choice to implement SIW feeding networks as low radiation-loss transmission lines.As an application for the mm-wave/sub-mm-wave systems, a holographic imaging technique has been studied and a spatial-domain image-retrieval technique has been proposed. Compared to the well-known spectral domain technique, this spatial-domain technique reduces the calculation costs especially when the object to be imaged is as big as a human body. Moreover, this technique allows for a cheaper imaging camera because it only needs amplitude measurements while in the spectral-domain technique phase measurements are also needed.
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Electrical Engineering - miscellaneous
ESAT- TELEMIC, Telecommunications and Microwaves

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