Development of Self-Powered Beacon for a CubeSat
Kyushu Institute of Technology, Applied Science for Integrated System Engineering
Rahmi Rahmatillah (14350941), Supervisor : Prof. Mengu Cho
1. Introduction
The number of satellites launched annuallyactivation system. In this research, part 2) to 4)
are developed.

into the space is growing. However, the high

3. Part’s Development

rate of failure is still one of the issues for space

3.1 Patch Antenna

projects. Satellite failure may be caused byTo avoid failure because of deployment

insufficient power generated, communication

system, patch antenna is used. The patch

system failure, damage from debris, deployment

antenna is designed and simulated in CST

failure, and so on. Lost communication from thedesign studio software. There are two designs insatellite is the worst condition that can happen in

the development: a) design for 437 MHz and b)

satellite mission. To mitigate this problem,

design for 421 MHz.

Self-Powered Beacon (SPB) is developed in thisresearch. SPB is a separated communication
system in the satellite which sends beacon signal
continuously to the ground.
2. Overview of SPB System
The basic principle for the SPB system isshown in Figure 1:
Figure 2 Patch antenna design
The antenna designs are fabricated byetching process and give frequency resonant
value for design (a) is 436 MHz with S11 = -13.5dB, gain 0.66 dBi. For design (b) is 421.25 MHz
Figure 1 Basic principle for the SPB

with S11 = -34.1 dB, gain has not been tested.

SPB is supposed to be attached on one

3.2 Transmitter and Microcontroller Circuitsurface of 1U CubeSat. This system will start toDesignwork when the solar cell is illuminated by theTransmitter that is used in this research issunlight and provide current to SPB load. TheADF7021 N with microcontroller PIC16F876A

system is self-powered without using battery.

for programming. It is programmed with register

The SPB consists of: 1) a Solar cell, 2)value. The PCB model for the transmitter istransmitter for beacon, 3) antenna, and 4)

shown in Figure 3. The transmitter is configured

environment switch as the requirement of

to send the signal in frequency 437 MHz.

environment conditions considered here: Atomic
Oxygen (AO) and Thermal Cycle. For AO
condition, the switch is made of silver wire withthickness of 0.1 mm. After experiment, theswitch was not fully degraded. It will require
longer time to make the silver wire fully
Figure 3 Tx – antenna integration

degraded. For thermal cycle condition, theThe spectrum result is shown in Figure 4. It isswitch is made of metalized polyimide attachedprogrammed in FSK modulation with 4KHz

to a substrate. The design is shown in Figure 6.

deviation.

Figure 4 Output spectrum for 437.3 MHz
3.3 Environment Switch

Figure 6 Environment switch design
There are two substrates used in the experiment:

The switch is used to activate the SPB

aluminum and rubber. For aluminum, the sample

system. There is a requirement from thebreaks after 12 cycles, while for rubber thelauncher that no signal is transmitted prior tosample breaks after 10 cycles. Both of thoseseparation. To avoid electrical failure, switch

experiment were done with temperature range

based on environmental condition of space is-100 to +100 0C.

developed. The concept for the switch is shown

4. Conclusion

in Figure 5.

Patch antenna, transmitter-microcontroller,
and environment switch are developed in thisresearch. The design for patch can give theresonant value of 436 MHz. Transmitter isprogrammed and can transmit data in range 437
MHz, but the data decoding has not finished yet.
Environment

switchisrequiredfor

theFigure 5 Environment switch concept

activation system. From the experiment, it is

The switch is expected to prevent current frombetter to choose substrate for the switch that has

going to the load. When the switch is exposed tothermal coefficient larger than Kapton’s thermal

the space environment, it is supposed to becoefficient.

degraded, burned, or broken. There are 2