In this chapter, a single element of wearable antenna is designed, and further, to enhance the gain, a wearable rectenna array is designed that can be utilized for the purpose of energy harvesting at 3.14 GHz. The theoretical analysis of received power has been studied. The anticipated antenna array shows the directivity of 8.048 dBi that was used to calculate received power by antenna array at the distance of 10 meters from transmitter. This rectenna array can be used to operate the micro-electronic gadgets and to operate small sensors.
TopIntroduction
Many Industries create some impact on wearable devices. At present time it is the need to keep our self hands free and wireless so the wearable antenna as rectenna fulfills such type of requirement. Wearable rectenna can be the source of a small amount of power to operate some devices like sensors. It is easily wearable and flexible in nature that can be used to harvest the energy. Electromagnetic wave which have high frequency in Gigahertz associated with some amount of energy at the particular frequency so this energy can easily captured by the anticipated antenna and then it is used to operate the device which required the small amount of power (Electronic, 2008; ECC, 2007; Chaudhary, Kim, Jeong and Yoon, 2012).
Here specific transmission frequency is used. There is some standard level of frequency exist in our surrounding like mobile communication frequency range, Bluetooth frequency, radiolocation frequency and at this particular frequency, some amount of power density is available in the environment so we can design the wearable antenna that can operated at particular frequency which able to receive the power and used to operate some microelectronic equipment and gadgets. When the single antenna is to be used, it have some gain in dBm (Decibel milli) but to increase its gain, the combination of multiple antenna is used this arrangement called rectenna array (Naresh and Singh, 2017a; Naresh and Singh, 2017b; Hameed and Kambiz, 2017; Wang, Li, Xu, Bai, Liu, and Shi, 2013; Naresh, Singh, Bhargavi, Garg and Bhoi, 2018a). So here antenna array is designed which have larger gain as compared to single antenna which is operated at four resonant frequency. In this chapter the theoretical analysis is occurred only for 3.14 GHz frequency. According to Federal communication commission (FCC) the range of 3.1 GHz to 3.4 GHz is to be used for radiolocation purpose.
Background
Rectenna is the part of wireless power transmission. The demonstration of wireless power transmission was performed by NASA (National aeronautics and space administration) in 1975. In this demonstration 34000 watts of power was safely transmitted over the 1.5 Km range. In that transmission system, 26 meter long antenna with the 0.5 Megawatt transmitters was used. At that demonstration the large amount of energy was transmitted through antenna this cause the huge radiation so such type of system cannot be established in general use. In this chapter wearable antenna is discussed for energy harvesting (to harvest the received energy of antenna, rectenna circuit is to be used) so this wearable antenna is fabricated on textile material (jeans) and can be fabricated on cloth so this is considered as wearable textile antenna. In this chapter the theoretical analysis is performed to analyze the minimum received energy by wearable antenna, when it is placed at 10 meter distance from radar transmitter.
Main Focus Of The Chapter
According to Electronic Communication Committee (ECC) report (within the European conference of postal and telecommunication administration) Kristiansand, June 2018 (Electronic, 2008), the range of between 3100-3400 MHz, which is used in radiolocation system, the characteristics of that frequency range has been described in Table 1 in case of radar transmitter. In this chapter the main focus to analyze the minimum power received by wearable antenna at minimum power density (for minimum radar emitted power 55 dBm) of radar transmitter when antenna placed at 10 meter distance from transmitter.
Table 1. ECC report for 3100.3400 MHz
| S. No. | Characteristic Name | Min | Typ | Max |
| 1 | Radar transmitter emission power (peak power) in dBm (Pe) | 55 | 80 | 95 |
| 2 | Antenna gain in (dBi) in antenna main beam (Ge) | 25 | 35 | 45 |
| 3 | (Pe+Ge) Peak EIRM according to distance coverage in (dBm) | 80 | 115 | 140 |