# On-Orbit Experimental Result of a Non-Deployable 430-MHz-Band Antenna Using a 1U CubeSat Structure
## 1 Introduction  
The 1U CubeSat is one of the most popular lean satellite platforms. A lean satellite is a satellite that utilizes nontraditional, risk-taking development and management approaches with the aim to provide value of some kind to the customer at a low cost and without taking much time to realize the satellite mission [1]. A 1U CubeSat is about the size of a 10-cm cube. Many 1U CubeSats have carried 430-MHz amateur band transceivers and dipole or monopole antennas as their communication system due to limitations in volume and power generation capability. A 430-MHz-band antenna on a 1U CubeSat requires a deployable structure due to its wavelength. However, it is difficult to make such a deployable structure reliable. Particularly in the case of a 1U CubeSat, there is little volumetric margin for redundancy, so in many cases it is a single point of failure. [PERSON] et al. [2] prototyped a 1U CubeSat and developed the standard CubeSat deployer known as PolySat and P-POD (Poly-Picosatellite Orbital Deployer), respectively. It was one of the early CubeSat developments. It was equipped with 430-MHz band radio and four quarter-wavelength elements made by a spring ribbon. These elements were rolled under +Z panel before deployment from P-POD and held in place with monofilament. The monofilament was cut by nichrome wire after deployment and the antenna elements were deployed. [PERSON] et al. [3] developed XI 1U CubeSat. The satellite was launched in 2002. The satellite was equipped with a dipole antenna of 430-MHz for downlink and a monopole antenna for 145-MHz for uplink. These antenna elements were also rolled on +X panel before deployment from P-POD and held with nylon wire that will be cut after deployed from P-POD by nichrome wire. [PERSON] et al. [4] developed Quetzal-1 1U CubeSat. The satellite was launched in March 2020. It was deployed from J-SSOD (JEM Small Satellite Orbital Deployer) in April 2020. It was equipped a COTS (Commercial Off-The-Shelf) deployable antenna system manufactured by GOMSpace. The antenna was a turnstile antenna consisting of four monopole antennas. These four antenna elements were rigid rod type, and they had spring to deploy. Before being deployed from J-SSOD the elements were folded along the side of the CubeSat with a wire that was cut after being deployed from J-SSOD by heating resistors. The COTS antenna is now widely used by 1U CubeSats that employs a commercial CubeSat bus. As shown in the three examples above, deployable antennas have been used for UHF in 1U CubeSat from the early days to the present. [PERSON] et al. [5] surveyed antennas used in the past CubeSats and compared 10 different antenna designs in the UHF band (300 MHz\(\sim\)1 GHz). Nine designs were deployable antennas and only one was a non-deployable antenna for 1.5U [6]. Non-deployable design for 1U was not addressed in Ref. [5]. Patch antennas have a low profile and the right weight characteristics and are candidates for non-deployable antennas; however, they can only operate efficiently at higher frequencies such as S-band within 10 cm \(\times\) 10 cm. The power consumption of transceivers that handle such high frequencies tends to be high. There are few examples of such transceivers being installed in 1U CubeSats. Meanwhile, there is some research about 430-MHz-band compact patch antennas that can fit on a 1U CubeSat. [PERSON] et al. designed a 72-mm \(\times\) 32-mm patch antenna [7] operating in the 430-MHz band and mounted it on a 1U CubeSat. A similar patch antenna was also designed independently for a 1U CubeSat at Tsukuba University and mounted on ITF-2 [8]. It supported not only the 430-MHz band but also the 145-MHz band. Both examples will occupy about half of a certain external panel of 1U CubeSat. This is a disadvantage in terms of power generation capacity. In CubeSat designs, one has to make trade-off between the system reliability and the system performance. Non-deployable antenna avoids the satellite communication loss due to the deployment failure, making the satellite reliable.