Abstract
Recently, indoor broadband radio communication becomes an integral part of daily life, especially with the widely spread of smartphones and tablets which causes a great increase in Internet users demanding fast speed Internet communication. Current systems, which operate under the 10 GHz frequency band, cannot satisfy the maximum needs of short-range high data rate wireless communications for the long time. In millimeter waves range there is 9GHz free bandwidth which support extreme high data rates for the vast numbers of users. The wideband millimeter- wave transmission in the range of 60 GHz to be a committed way to meet the need of requirements of the next generation Wi-Fi 5G networks in terms of increased data rates. The aim of this research work is to design a single layer sectoral horn H-plane mm-wave antenna as well as antenna array using Substrate Integrated Waveguide (SIW) technology for millimeter-waves short range high speed Wi-Fi 5G network systems. The benefits of presented antenna are high gain, low cost, small size, easy to integrated with the other planar circuits and suitability of its application for 60 GHz band due to the appropriate signal propagation properties in the SIW. The design work will be carried out using RF simulation tools. Theoretical analysis and numerical simulations of the presented antenna configuration will be carried out to increase bandwidth and gain of antennas. Initially a SIW H-plane sectoral horn antenna with a substrate (RT/duroid 5880) will be designed. Next step would be to further increase the gain, directivity and enhanced the bandwidth of the antenna by optimized the antenna parameters and by using some form of antenna arrays. The research work will explore the theoretical and empirical models for the proposed antenna. Finally, possible experimental validation and fabrication will be carried out.
Key Words: Millimeter-waves (MMW), Horn antenna, SIW, Spectrum, CST.
Introduction
Millimeter-waves generally occupy frequency spectrum from 30GHz to 300GHz, that matching wavelengths between 10mm and 1mm as seen in Figure1[1]. Recently, the most common millimeter-wave bands of spectrum are located near 38, 60, 79 and 94 GHz that have been allocated for the purpose of wireless communication in the public domain. However, we will focus on 60GHz band, which makes lot of modern applications viable that are hard to offer by lower frequency systems.
Short-range systems at 60GHz band have many merits contrast to systems at lower carrier frequencies. The main benefits of 60GHz frequency range are the large bandwidth with free license, which allow ultra-data transfer speeds, also in the millimeter-waves conducts to types of antennas with small dimensions, to make even array antenna systems. . Moreover, this band does not interfere with existing wireless systems. Considering of the attenuation and losses are high due to transmission through walls, trees and others obstacles, the coverage area of cell stations are small, also little interferences maybe exist by other millimeter-wave systems and neighboring radio cells. Furthermore, millimeter waves energy absorbed by the atmosphere, limiting their range. There are many environmental factors results high attenuation in signal air path, like Rain, moisture and fog, this attenuation reducing cell coverage distance. Many gazes absorption significantly affect the signal power at 60 GHz like Oxygen and humidity of water as shown in (Figure 2). The loss can be minimized by choosing frequencies in the curve valley. In addition, massive gain and good directivity antenna arrays can raise the effectiveness radiated power ERP, significantly increase distance of coverage [2].
Figure 2. Atmospheric absorption across mm-wave frequencies in dB/km.
Millimeter-wave based on 60 GHz has been received a lot of attention as a major catalyst for 5G cellular networks and indoor networks.
Unlicensed large bandwidth one of the main reasons giving more interest in 60GHz technology.
We summarize the availability of unlicensed 60 GHz spectrum worldwide. Figure 3 shows that, the available bandwidth in some countries about 5GHz at least. In USA, there is available unlicensed band between 57 and 64GHz. In addition, band between 57 and 66GHz is for some wireless application used in Europe. Smaller band has assigned in Australia from 59.4 to 63 GHz. Also in Korea and Japan allocated 57-64GHz and 59-66GHz bands respectively. Consequently, almost 7GHz of spectrum can used freely worldwide for 60GHz techniques [3].
Figure 3. International unlicensed spectrum around 60 GHz.
LITERATURE REVIEW
During the last decade, the license-free 60-GHz band or other mm-Wave available bands had been attracting the attention of many researchers in order to design and implement the electronic components, antenna designs and modulation techniques to make this short range communication viable to all following certain standards. Most of these designs and circuit structures used SIW technology in their design as characteristic of this technique at this frequency bands. Following are some well-known designs for improving the performance in terms of bandwidth and directivity of 60 GHz radio.
Z. Wang et. al. [11] proposed high gain and performance of radiation SIW horn antenna. This antenna was incorporated in substrate of four-layer. Simulation result was more than 8 GHz bandwidth, and more 8.5dBi gain within the whole band that with the high efficiency of radiation over 94%. This result showed that antenna is suitable for millimeter-wave communications and able to cover the unlicensed 60GHz band. In[12], a conventional planar horn antenna has been proposed H-plane horn antenna which has wide beam in the E-polarization and high directivity in H-plane. This study dealt with widening the bandwidth, matching and decrease the multimode spreading. CST Microwave Studio software was used to evaluate the matching and resonance by studying the dimensions of the horn dimension. The 10dB simulated bandwidth of proposed antennas was almost 5GHz at 60GHz center Carrier.
Authors in [13] proposed a compact high gain and wideband mm-Wave antenna for 60 GHz communication systems. The proposed antenna consists of a multilayer structure with a hole coupled micro strip line and a surface mounted horn integrated on substrate of FR4. The proposed antenna contributes impedance bandwidth of 8.3% (57.4–62.4 GHz). The overall antenna gain and directivity are about 11.65 dBi and 12.51 dBi. H-plane SIW horn antenna with a dielectric lens was proposed in [14], which was planning and studying, as a new structure of SIW construction with size is 39.175×14×2 mm3 and frequency range 25.5 to 28.5 GHz. The measurement of antenna were bandwidth is over 12% at -10dB return loss and gain about 9 dB.
Planar horn antenna Experimental radio Link is proposed in [15] for 75/85 GHz, which combines two approaches. This literary work developed that horn antenna by addition novel transition between the air and narrow substrate. The novel transition enhances the radiation pattern and the impedance matching of the antenna. In addition, this work achieved Directivity above 5 dBi in comparison with other structures of horn planar antenna.
The geometry of the proposed antenna in my thesis is inspired from [14]. The basic difference in my design, from [14], is the addition of the strip lines to improve the bandwidth and the directivity at 60 GHz which taken from [15]. The significance of the horn antennas since long time ago as a high directivity antenna and currently with SIW technique to be suitable for mm-Wave applications. Therefore, these type of antennas will be the most promising candidate for the high speed Wi-Fi and WLAN networks to carry the huge networks traffic.
Problem statement
The first step towards the design of the suggested horn antenna was to implement a single layer SIW horn antenna at 60 GHz as shown in Figure 4. SIW is created in the substrate of RT/duroid 5880 having relative permittivity ðœ€ð‘Ÿ = 2.2, loss tangent ð‘¡ð‘Žð‘› 𛿠= 0.002 with thickness 0.762mm and copper cladding thickness 0.0175mm is used. The metalized via holes are designed to create SIW. Copper with a conductivity of = 5.8 × 107ð‘ /ð‘š is used for cladding and via holes. As predicted the single layer antenna, without optimization and without matching between the air and the SIW substrate, gave very poor return loss with S11 > -10 dB as shown in Figure 5. In addition, the SIW design parameters are calculated by following the rules provided in the literature [7]. Next, matching between the SIW will carried out by using striplines and dielectric lens. The structure is shown in figure 6. In addition, the antenna will use the same RT/duroid 5880 substrate with thickness 0.762mm.
Figure 4. SIW horn antenna structure.
Figure 5. Return loss of single layer SIW-horn antenna without matching at 60 GHz
The return loss S11 (<-10 dB) had a bandwidth of 7 GHz i.e. (57-64 GHz) at a center frequency of 60 GHz as shown in Figure. 7. The gain and directivity achieved was 10.5 dB and 11 dBi respectively.
Figure 6. SIW horn antenna with lens and striplines structure.
The geometry of the proposed antenna in this thesis is inspired from [14]. The basic difference is the addition of the strip lines to increase the gain more than 12dBi, directivity and enhanced the bandwidth of the antenna by optimized the antenna parameters at 60 GHz.
Figure 7. Return loss of single layer SIW-horn antenna with matching at 60 GHz
RESEARCH OBJECTIVES
The thesis will be focused on designing an efficient mm-Wave antenna which will cover the unlicensed 7 GHz bandwidth at 60 GHz band and how can rotate it to cover the desired area when we use it in the 5G Wi-Fi networks or any short range wireless communication (WLAN, WPAN), using RF simulation tool, CST MWS.
Motivation and Thesis Work
Mm-Wave wireless communication is a technique that has great number of applications to deployment of emanating wireless networks as well as existing networks. The Wireless Gigabit Alliance (Wi-Gig) and IEEE 802.11ad are developing a multi-gigabit WPAN/WLAN networks specifications in the 60GHz band. The IEEE 802.11ad standard is aimed at providing data rate up to 7 Gbps. The measured range of Wi-Fi frequencies in the millimeter band is few meters, so will be used for very short distance (through a room) with high data rate like HD video. In the early days of the 60GHz, wireless communications, a lot of fixed wireless networks looks like the most appropriate application of 60 GHz, because of the needs of directional antennas to accomplish accepted link budgets [4]. Horn antennas may be the best candidate for system antennas because they have a broad bandwidth, high gain, excellent effectiveness and a compact fabric [5]. Due to the appropriate signal propagation properties in the SIW at 60 GHz band, SIW technology is very promising candidate for millimeter-wave applications [6, 7]. Mainly due to the facts, SIW is electrically similar to a conventional waveguide and can be easily integrated with planar circuits. In addition, it can be easily fabricated by low cost printed circuit board process [8].
The significance of SIW horn antennas have become widespread because of their attractive merits, such as, simple, low-cost manufacture, high directivity, small dimensions, easy to integrated with other planar circuits and suitability of its application for 60 GHz band. Many of the techniques explained in the literature improving the directivity and bandwidth of SIW horn antenna at different frequency bands [9, 10].
Research methodology
For the achievement of the above objectives, the research methodology will involve the following:
 Literature review of mm-wave antenna and H-plane sectoral Horn antenna.
 Study, theoretical analysis and formulation of antennas based on SIW in millimeter-wave region.
 Proposing a new architecture for the antenna.
 In depth study of existing 60 GHz radio antennas.
 Design of the suggested antenna using CST Microwave Studio (MWS) software and simulation verification by using (HFSS) Ansoft software.
 Result comparison and evaluation.
After successfully simulating the suggested antenna, its fabrication will be the next step if the technology permits.
RESEARCH GANTT
Research Tasks Tie Line (Months)
1 2 3 4 5 6 7 8 9 10 11 12
Literature review
mm-Wave antenna for high speed Wi- Fi in 5G networks basics, Theoretical analysis and selection of appropriate configurations.
Design and Simulation.
Implementation and possible Experimental characterization of the Designed configuration.
Writing the thesis