Design Considerations for LTCC based UWB Antennas for Space Applications B. Hussain, I. Kianpour, V. Grade Tavares, H. S. Mendonca INESC-TEC Faculty of Engineering, University of Porto Porto, Portugal [bhussain,ikian,vgt,hsm]@fe.up.pt G.Miskovic * , G. Radosavljevic * ,V.V.Petrovic † * Institute of Sensor and Actuator Systems * Vienna University of Technology, Vienna, Austria † TES Electronic Solutions, Stuttgart Germany * [goran.miskovic,Goran.Radosavljevic]@tuwein.ac.at † [email protected]Abstract—This paper presents a planar antenna using low temperature co-fired ceramics (LTCC) substrate for extreme environment applications. An ultra wideband (UWB) elliptical patch antenna was designed and fabricated using an LTCC Ceramtec GC substrate to demonstrate the capabilities of the technology for wideband applications. The simulated results were further validated experimentally. The fabricated antenna provides a peak gain of 5dB over a bandwidth of 4 GHz (3 GHz – 7 GHz) with return loss better than -10dB. The radiation pattern is omni-directional in the horizontal plane (θ=90⁰) over the whole frequency range. Keywords—LTCC, UWB Antennas, High Dielectric Constant Substrate I. INTRODUCTION Planar antennas offer a compact, cost effective and efficient mean to integrate transceiver chips. Conventional antennas such as horn, parabolic dish and dipoles are effective, but the need for portability and miniaturization on hand-held devices is not compatible in volume with such antennas. Thus, by resolving some of these problems, planar antennas have become by far the most widely used antennas in today’s telecom world. Planar antennas are usually realized on FR4 Epoxy substrates with copper metallization. Although it is a low-cost and efficient solution for most current communication systems, epoxy substrate does not perform well over a large bandwidth due to the fact that the dielectric constant is not strictly controlled. The durability of epoxy substrates is also very limited in harsh environments. Extreme heat conditions and high-pressure restrict the use of these antennas. In environments such as Venus (500°C, 90 Atmospheric) or deep underwater sensor applications, the epoxy based substrates cannot be used. Therefore, there is a strong need to find substrates that can replace epoxy and provide better performance. Ceramics are used in different industries due to their high durability and resistance to extreme environments. However, their high-firing temperatures strongly limit the use of ceramics with electronics. The extreme heat involved, during fabrication, in general is not suitable for metallization and chip integration. The alternative solution is to use instead the so- called low temperature co-fired ceramics (LTCC). This substrate technology is fired at relatively lower temperature, which has made them suitable for metallization with gold or silver. As LTCC is ceramic in nature, it has high durability against heat, moisture and other degrading factors. Another interesting feature of LTCC is that multiple independent layers can be prepared separately and subsequently fired together. Thus, a high degree of integration with electronic circuits can be achieved. On one hand, dielectric losses in LTCC are quite negligible due to low-loss tangent (0.001-0.005) [1], and on the other hand, LTCC has a relatively high dielectric constant (6 to 9) [1]. This provides the possibility for having a smaller antenna foot-print. In the past decade a good amount of research was directed towards the achievement of LTCC substrates that could be used for high-frequency applications. Traditionally, DuPont LTCC tapes became preferred in such cases [2]. These tapes possess excellent characteristics for RF design, such as low- loss, stable dielectric constant and silver/gold compatibility. However, it becomes rather difficult to deposit large metallization surfaces without deformation. Alternatively, Ceramtec GC tapes offer almost identical characteristics to DuPont, but provide more stability for large deposition of metal structures. This paper then presents an elliptical patch antenna fabricated from Ceramtec GC tapes. The antenna is designed using commercially available EM tools (HFSS) and simulated results are validated using anechoic chamber measurements. The remaining of the paper is organized as follows. In Section II, design challenges of LTCC are discussed. Section III presents the antenna design and simulation results. The experimental verification is provided in Section IV. The analysis of results and conclusions are finally presented in Section V.
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Design Considerations for LTCC based UWB Antennas for ... · The antenna is designed using commercially available EM tools (HFSS) and simulated results are validated using anechoic
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