Arke UHF Phasing Board

Arke, the UHF phasing board, is responsible for circularly polarizing the turnstile antenna on the ram face of the satellite. This is important because the satellite undergoes changing orientations in orbit and circularly polarized waves allow for the relative orientation of the satellite to not affect the antenna’s effective gain.

Specifications

Arke is able to polarize the antenna by keeping the four dipoles of the turnstile antenna in-phase 90 degrees apart. Arke will be the mounting board for the UHF antennas (canted turnstile) and is going to be used with Endurosat’s UHF transceiver. Arke is capable of handling up to 2W (subject to increase) of input power from this transceiver. The antennas are going to be mounted as rods on spring hinges in a burn wire configuration with a polarization scheme of RHCP up and LHCP downwards.

2-D PCB schematic of the phasing board

3-D render of the phasing board

Specifications
PCB Dimensions (mm)
91.70 x 93.35 x 6.35
Mass (g)
TBD

Volume (cm3)

TBD
Frequency (MHz)
435 to 438
Antenna Gain* (dBi)
-1.5 to 1.5
Transmission Loss* (dB)
-2
Return Loss (dB)
< -10
Supply Voltage (V)
3.3

Operating Temperature (°C)

-55 to 85

*Preliminary estimates

Mechanical interface

4 M2.5 mounting holes that will allow for the PCB to be attached and interfaced on the Icarus CubeSat structure.

  • The primary connector consists of an SMB coaxial connector where its main purpose is to travel the RF signals between the SMB and UHF transceiver.
  • 6-pin Molex header for SPI communication.
  • 2-pin Molex header connecting the PCB to the ADCS magnetorquer.
SPI Header Schematic Diagram

The main purpose of the SPI header is to provide SPI signals towards and from the ADC onboard Arke, therefore it will digitally identify the analog voltage data from the onboard temperature and photo sensor.

  PinNet Abbreviations
13V3
2GND
3SPI CLK
4SPI MISO
5SPI MOSI
6S ADC SPI nCS
M1GND
M2GND

This hasn’t been decided yet.

  • Altogether, the board and its components are not expected to generate a significant amount of heat
  • Smaller vias within larger vias where the rod holes ensure that there is a good thermal conductivity between the rods and the board.
  • UHF antennas will be under AlbertaSat’s burn wire system.
  • The commands for the system are sent from the OBC, which removes the need for having the burn wire control on Arke.
  • Arke will have hinges that springs and stops for deployment of the antennas once the burn wire is released.
  • Arke is not equipped with fragile electronic components but proper static discharge and contamination prevention procedures should be followed nonetheless.
  • Ideal protective measures would include:
    • wearing grounding attire
    • being cautious of ambient room conditions

By Ryan Yeung, Justin Ta and Anirban Mistry
This page was last updated February 2021

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