Millimeter Wave Antennas for Wearable Applications

Introduction

WBAN is a multi-tier network. WBAN can be used for medical purposes. Small biosensors can be worn around or implanted in the human body. Biosensors can be put around the wrist, chest or legs. The implementation of biosensors in human body is still an area of research. These biosensors monitor and record human health parameters. In this case sensors will be put around the human body in the form of antennas, which will record various health parameters. The focus in this chapter is not on the actual measurement of parameters but it could be more on antennas that are required for such an application. Sensor nodes are connected with sink node which are connected to the medical server through PDA or Laptop. Medical server at remote location receives data which contains patient’s daily report and his vitals. The sensors will be placed on the human body, body will communicate with sensors through PDA or laptop, it could be a mobile handset as well. Then the mobile handset will transmit the signals to medical servers, which will be accessible to doctors. Body area networks apart from medical applications can also be implemented for military and sports training, interactive gaming, and information sharing. The antenna design is one of the critical part in wearable antenna technology because antenna works as a sensor which will take certain information from body and then communicate it in a useful manner. In order to overcome the problems associated with wearable antenna technology some special antennas and technologies have been developed, which will be discussed in this chapter. There are two basic scenarios for body centric communication. One is On body to Off body propagation, the dots shown in the figure.1 are biosensors which are basically antennas. The biosensors on the body communicate with the personal device, then the signal via internet passes on to the medical server. In this case the propagation is usually perpendicular to the body and broadside pattern will be required. The antenna that would radiate minimum exposure towards the body will be required. Typically, the antenna radiates in both the directions i.e., forward and backward directions. The antenna that is communicating to personal device will also send some energy in the body. the body will also be exposed to electromagnetic energy. Therefore, we should have antenna that would give minimum exposure towards the body. The second scenario is On body propagation, in this case biosensors communicate with each other. For example, the antenna at the heart shown in figure 1 will communicate with the other antenna on the head or hand and so on to perform different functions. For on body propagation the pattern should be tangential to the body or it should be end fire pattern.

Figure 1.

Body centric communication