WEARABLE ANTENNAS 3.8 AND 5.6 GHZ USING FOR INDOOR CHILD MONITORING

In latest years the progress and employment of wearable antennas have developed quickly for human monitoring applications. Due to shrink of wireless communication equipment reasons, the microstrip patch antennas with size-reduced are preferred. In this paper, two wearable antennas with different shapes (similar to the button) are introduced. These are compatible for a commercial wireless system platforms such WiFi and WiMax standards. The proposed antennas are very suitable for child indoor monitoring purposes. Here, because of the small size of these antennas (the largest dimension approaches to 25 mm), the assumption of bending the surface, substrate and ground layer are neglected. The operation frequency band for the first antenna is between 5.4 and 5.6 GHz, while its between 3.6 to 3.8 GHz for the second and both with a linearly polarized radiation. For a wearable antenna, a conductive textile was used for the substrate layer, a permittivity of 4.4 is used. A 52% size reduction result of the rose patch size (the 2 nd antenna) compared to the size of a regular rectangular patch antenna (the 1 st antenna) additionally, investigations had been conducted for different antenna without bending and the antenna’s performance in vicinity to human body. The proficient multiphasic COMSOL software is used for simulation.


INTRODUCTION
The microstrip patch antennas with size-reduced is favourite for modern wireless applications [1,2]. These type of antennas is very suitable for wireless body area networks (WBAN). WBAN have increased attention because of their wide applications in civilian and military, which used in medical sensor systems, rescue service applications, military communication or personal entertaining [3]. WBAN's applications in monitoring services have been growing. Many bands of frequencies allocated for WBAN, such the Medical Implant Communication System (MICS) where 400 MHz is used, 2.4 GHz and 5.8 GHz bands for the Industrial Scientific Medical (ISM), low and high frequencies of the Ultra-wideband (UWB) which lie between 3 and 10 GHz band [4][5][6][7].
In recent times, rapid increasing wireless equipment encouraged the development of modern wireless standards such WiFi and WiMax [6][7]. Recent communications have characterised the transmission between different antennas located around the body [8]. Wearable antennas have already been developed as metal patches with different shapes on textile fabric [7]. The antennas published in [8] were probe fed and linearly 1. GEOMETRIES OF THE DESIGNED ANTENNAS Two of geometrical shape of antennas with small size are introduced. The shapes of these antennas are similar to the button, where these entries are very suitable for clothing. The design of these antennas are taking of the base of a substrate square with size of 0.02 mm 2 as a wearable one for the child monitoring purpose. The line feeding technique for such type of antenna is microstrip which has been used for the basic circular button microstrip patch antenna. The detail of the dimensions of these aerials are shown in Figure 1 and  The horizontal and vertical views of the first antenna are shown in Figure 3a and b , respectively. In other side, the horizontal and vertical views of the second antenna are shown in Figure 4a and b, respectively. Table 1 and 2 have the geometrical characteristics of the antenna 1 and 2, respectively.   2. RESULTS AND DISCUSSIONS Figure 5 related to the simulated electric field norm for the proposed first antennas. Figure 6 shows the radiation pattern in 2D for the same antenna. the antennas have a good return loss for 3.6 GHz with respect to less than -14dB as shown in Figure 7. Desired characteristics of WiFi and WiMax is achieved through the first antenna.
It's obvious from Figure 9 that for the resonant frequency of 5.6 GHz the return losses parameter S 11 is less than -20 where its very suite to such application with respect to the required quantity of -10 dB for such task. Also this frequency is standard frequency for WiFi, and local area requests. The desired frequency component is in band of 5.3 to 5.6GHz. The antenna realizes the required conditions for wireless body purposes.
The two dimensions (2D) far-field [V/m] radiation patterns in of the proposed antenna (see Figure 8), which denotes to the directivity and the gain of the antenna. The intensities of electric field is drawn for the fundamental frequency of our antenna as shown Figure 5. To estimate the energy density per cubic meter through time interval.  Performance of the most effective parameters of the antennas were considered.
From the results of antenna 1's simulation , it is found that the improved resonant frequency has shifted from 5.1 GHz to 5.9 GHz with same size and dimension of patch antenna. It shows the return loss less than of -20 dB at 5.6 GHz resonant frequency. For the antenna 2 the best resonant frequency is 3.8 with insertion loss equals to -14 dB.