Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance of antenna designs that use polymer substrates. Moreover, we explore a selection of flexible materials for flexible antennas in IoT applications, namely Polyimides (PI), Polyethylene Terephthalate (PET), Polydimethylsiloxane (PDMS), Polytetrafluoroethylene (PTFE), Rogers RT/Duroid and Liquid Crystal Polymer (LCP). The study includes a complete analysis of bending and folding effects on the radiation characteristics such as S-parameters, resonant frequency deviation and the impedance mismatch with feedline of the flexible polymer substrate microstrip antennas. These flexible polymer substrates are useful for future wearable devices and general IoT applications.

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In this paper, a printed Yagi antenna with an integrated balun is proposed for CubeSat communications. The printed antenna is mechanically adjustable to realize three functional states at different operating frequencies in the L-band and S-band respectively. Three different angle deployments are proposed at 10°, 50° and 90°, so that the antenna operates at three different operating frequencies, namely 1.3 GHz (L-band), 2.4 GHz (S-band) and 3 GHz (S-band). The measured results of the fabricated antenna are well matched with the simulation, having frequencies of 2.82–3.07 GHz, 1.3–1.4 GHz and 2.38–2.57 GHz, with similar radiation patterns. The measured gain of the antenna is 8.167 dBi at 2.4 GHz, 5.278 dBi at 1.3 GHz and 6.120 dBi at 3 GHz. Keeping within the general theme of cheap off the shelf components for CubeSats, this antenna design allows the CubeSat designers to choose from three popular frequencies, through a simple angle configuration. The main contribution of this work lies with the reconfigurable frequency, relatively high gain and simplicity of design.

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CubeSats are attracting interest from both the industry and academia because of their affordability. Specifically, they are made from commercial Off-The-Shelf (COTS) electronic circuit chips, and are thus seen as a cost effective replacement for traditional, expensive satellites. Moreover, they are expected to have higher capabilities to better support demanding missions. To date, most CubeSats rely on a single element antenna that usually has a relatively low gain and are not steerable. Thus, they are not suitable for long-distance communications and for use by missions requiring high-speed links and adjustable radiation patterns. Existing single element antennas also increase the probability of failure when establishing communication links, as the failure of the single element would lead to a disconnection. In this paper, we propose a 3x1 dipole antenna array and a cluster of three 3x1 dipole antenna arrays for CubeSats. Each array can theoretically be used on a separate frequency. Advantageously, all three arrays can be combined to enhance directivity. Our simulation results show that the proposed antenna cluster has a high gain of 5.03dB and wide directivity. Abstract-CubeSats are attracting interest from both the industry and academia because of their affordability. Specifically, they are made from commercial Off-The-Shelf (COTS) electronic circuit chips, and are thus seen as a cost effective replacement for traditional, expensive satellites. Moreover, they are expected to have higher capabilities to better support demanding missions. To date, most CubeSats rely on a single element antenna that usually has a relatively low gain and are not steerable. Thus, they are not suitable for long-distance communications and for use by missions requiring high-speed links and adjustable radiation patterns. Existing single element antennas also increase the probability of failure when establishing communication links, as the failure of the single element would lead to a disconnection. In this paper, we propose a 3x1 dipole antenna array and a cluster of three 3×1 dipole antenna arrays for CubeSats. Each array can theoretically be used on a separate frequency. Advantageously, all three arrays can be combined to enhance directivity. Our simulation results show that the proposed antenna cluster has a high gain of 5.03dB and wide directivity.