Multiband Dual-Meander Line Antenna for Body Centric Networks Biomedical Applications by Using UMC 180 nm

This paper presents a compact on-chip antenna architecture for 5G body centric networks (BCNs) applications. A dual meander line (DML) integrated antenna consists of two stacked layers of two turns of meander lines and a ground metal layer. The DML structure decreases the resonant frequency, increases tuning bands and broadens the operating bandwidth to be a suitable choice for high data rate biomedical applications. The antenna’s performance is evaluated in both scenarios inside and outside the human body. The proposed antenna is fabricated using UMC180 nm CMOS technology with a total area of 1150µm×200µm, and operates at bands 22 GHz, 34 GHz, 44 GHz and 58 GHz with an operating bandwidth up to 2 GHz at impedance bandwidth ≤ 7.5 dB (VSWR≤2.5). The proposed antenna is simulated using high frequency structure simulator (HFSS) and shows good agreement between measured and simulated results.


Introduction
5G technologies have the potential to make significant contributions to providing secure healthcare-orientated wireless networks with improved energy efficiency. Ultrawideband (UWB) communication becomes the solution of the higher demand capacity to multiple devices in 5G technology. UWB is a key component in many applications as radar imaging and smart biomedical sensors, which can be worn or implanted in the human-body [1][2][3]. Recently, these biosensors created closed UWB wireless body centric networks (BCNs) as shown in Fig.1 [4]. Body-centric wireless communications refer to human-self and human-to-human networking with the use of wearable and implantable wireless sensors. BCNs is a subject area combining wireless body-area networks (WBANs), Wireless Sensor Networks (WSNs) and Wireless Personal Area Networks (WPANs).
Body-centric wireless communications technology has numerous applications in healthcare, smart homes, personal entertainment, identification systems, space exploration and the military [5][6][7][8]. Battery lifetime in surgically implanted devices still a great challenge as the network has to last for years. Recently, implantable antennas have been largely studied for many sensing and wireless communication applications with tremendous need for integrated wireless powering techniques as energy harvesting/wireless power transfer module to reduce the need for regular battery replacement [9]. Multiband antenna are a potential solution for simultaneous wireless information and power transfer (SWIPT) technique for data rate and the long standby time in the fifth generation (5G) mobile communication systems [10][11][12]. In order to achieve fully integrated sensors, CMOS technology is employed to design implantable antennas. In such a case, not only the size of antenna itself can be minimized, but also a wireless powering module can be integrated on the same chip.
In this paper, a multiband on-chip antenna is designed and fabricated by UMC 180 nm CMOS technology. The proposed antenna structure is shown in Fig.2  antenna and other antenna parameters are shown in section 5. Finally, a conclusion of the paper is shown in section 6.

Antenna Configuration and Design
In order to provide good wireless communication from outside the body to inside, factors such as high tissue conductivity, biocompatibility and small antenna size must be taken into consideration. Furthermore, simulation models and physical models are also important to predict the behavior of the antenna in the presence of human-body. The most commonly used models are one-layer models and three-layer models, which were compared in [13] and the results showed that the measured input parameters can be quite different from the real ones if the antenna is to be implanted in the fat layer, otherwise, no significant differences were observed. The dual meander line (DML) antenna is fabricated using UMC180 nm CMOS process. The technology layers consist of a low resistivity Silicon substrate, six metal layers embedded in inter-dielectric layers, with the upper metal layer M6 being covered with a dielectric passivation layer. As shown in Fig

Antenna Performance Results
The design and performance of the DML antenna are measured using a high frequency   Fig. 4(a), while the resulting input impedance both real and imaginary are shown in  The results show that when the human body effect is presented, the antenna impedance matching is more significant for implanted of the antenna inside the human-body. The resonant frequency is shifted down and the operating bandwidth is increased. The other parameter studied is the reflection coefficient phase, which is slightly changed when the antenna is placed outside humanbody, and it is abruptly changed when the antenna is implanted in the human-body. The

Measurement of the Proposed Antenna
The proposed DML antenna reflection coefficients are measured in the microstrip Lab, at the Electronics Research Institute. The reflection coefficient achieved by using on-wafer probing and the setup composed of one GSG 67 GHz PicoProbe-RF probe (pitch: 150 µm) and ZVA67 Rohde and schwarz vector network analyzer from 10 MHz to 67 GHz as shown in Fig. 8(a). The fabricated UMC180 nm die (miniasic 1525µm×1525µm) was fixed at PM5 KurlSuss manual probestation. The photo of the fabricated antenna is shown in Fig. 8(b) with four ground PADS which are connected to the ground metal layer M1. Fig. 9(a) Table 1 at different resonant frequencies.  Table 2 shows the performance comparison between the proposed antenna and other previous literature reviews of the integrated antennas operating within the frequency range. In the 60 GHz band, the proposed DML antenna indicates a comparable gain with [18] and [20] with larger bandwidth and achieved multiband of operation. While [22] and [21] are lower gain and single band of operation at frequency higher than the proposed antenna, both antennas have the same efficiency (35%) at 65 GHz range. In references [17] and [18], antennas resonate at 24GHz but with narrow bandwidth and a larger area than the proposed antenna. While [19] and [20] have the largest antenna size area with a high gain. The proposed antenna has low antenna gain at lower frequency; this can be explained due to the small area which reduces the aperture area of the antenna. The  proposed antenna is compact when compared to other structures and it has a large number of operational bands. The multiband of operation with wideband bandwidth makes the proposed antenna a good choice for BCN to cover a large number of sensors for many patients. Essentially, the antenna provides a wireless power transfer system that can be integrated for battery less applications.