## 1 Introduction  
In this paper, we introduce an ultra-wideband (UWB) antenna that can be utilized in two major applications: (1) wireless body area network (WBAN) and (2) breast cancer imaging. A wireless body area network (WBAN) is a collection of low-power, miniaturized, lightweight wireless sensor nodes that monitor human body functions as well as the surrounding environment. WBANs play a very important role in the field of health services, enabling personal data monitoring, and are a leading area of research for health and disease management as well as monitoring human physiological activity such as health status [1]. The lightweight, ultra-low power wearable sensors in a WBAN can be classified as off-body, on-body, or in-body. These sensors can communicate wirelessly using both electromagnetic coupling and RF (radio frequency) communications. Wearable technologies have been used to monitor various parameters of the human body [2]. Wearable antennas as a vital part of WBAN systems can be used to send and receive pulses to the human body like a wearable bra to check a woman breast for the risk of tumour existence. Using this wearable bra as a part of a WBAN system, the patient will not be needed to go to the hospital, especially in the situation of COVID-19. Another application of UWB antennas is in the microwave imaging of breast cancer. The imaging is an alternative method to X-ray mammography, which has the advantage of no harmful radiation, no pressurized imaging that provides the ease of more frequent imaging, which can be a key in the early detection of tumours. There are multiple challenges in designing antennas in the presence of the human body, including the effects of high loss and high permittivity tissues [3]. All wearable antennas operate in close proximity to the high dielectric medium of the human body or have close interaction with the human body that affects the radiation characteristics of the design. As relative permittivity increases near the human body, it affects the Q factor of the wearable design and electric flux is suppressed [4]. Antenna performance therefore degrades when the antenna touches the body. Thus, antennas must be designed carefully to maintain performance when they touch a medium other than free space [5]. Furthermore, wearable designs must comply with standards for specific absorption rates (SARs). Several planar structures, metamaterial (MTM) structures [6], ferrite sheets [7], soft surfaces, frequency selective surfaces (FSS), and large ground planes [8] have been used in body area network (BAN) applications as insulating layers to protect the human body from unwanted radiation [9; 10; 11]. Bending and stretching of flexible and wearable antennas during use not only affects resonance frequency but also the radiation characteristics of the wearable antenna, especially when it requires circular polarization. Wearable antennas will inherently face different crumpling and bending conditions [12; 13; 14]. Human movements result in unpredictable, asymmetrical crumpling, hence, it is unreasonable to study a wearable antenna in a symmetrical crumple case [15]. Besides, controlling all these effects and keep consistency in performance during different bending conditions was performed to ensure that the resonant frequency operates within the required region [16] for multi-band or dual-band application. Flexible antennas (transparent and non-transparent) require high mechanical robustness and a high degree of bending (up to 90\({}^{\circ}\)) [17]. Antennas intended for on-body use should therefore be designed in such a way that radiation characteristics are not changed dramatically by bending [6; 17; 18]. When the antenna dimensions are small, the antenna can be more robust and less affected by bending [11; 19; 20]. Miniaturization has been a key factor in improving the performance of wearable antennas.