UHF Antenna II
The UHF Antenna II module is designed to cover the amateur satellite band 435-438 MHz. The antenna is circularly polarized, and uses a burn wire mechanism with feedback for the deployment of the antenna rods. The module has an internal microcontroller to control and monitor the release of the antenna rods. Communication to the module is via an I2C interface. The module uses a triple redundant system to ensure deployment of the antenna rods. The burn wire mechanism has double redundancy. In addition, the microcontroller can be bypassed to control the burn resistors directly via general purpose inputs on the module interface. The feed network for the RF part of the antenna is realized using strip lines. Each rod is fed with a 90 degree phase shift so that the antenna has a circular polarization. The antenna has a through hole for connecting it to EnduroSat’s 1U Solar Panel Z.
The deployment mechanism uses burn resistors to melt a nylon wire and release the doors holding the antenna rods as well as feedback switches to indicate successful deployment. For redundancy purposes, each antenna rod deployment mechanism has two independent circuits of burn resistors and two independent deployment feedback switches. The module uses a six pin Molex Pico-Lock™ connector with an I2C interface for providing control and status of the antenna deployment, via an internal microcontroller. For redundancy purposes, the microcontroller can also be bypassed to directly control the burn resistors via general purpose inputs on the six pin Molex Pico-Lock™ connector. In order to avoid significant voltage drops (on the +5V power supply bus) caused by the currents required to heat up the burn resistors, then the length of cables to the module should be minimized. The recommended gauge of cable is AWG 24.
The frame and doors, used for holding the rolled up antenna rods, are made of hard anodized aluminum which prevents a short circuit between the frame and the antenna rods. Rods are made from Shape Memory Alloy (SMA) with super elastic properties to ensure a straight shape after release. The PCB is made from FR-4.
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Last updated: 2019-02-25