Monopole holder KanwalpreetKaur Communication subsystem & Integration subsystem
Monopole Holder (Exploded View, Internal) Bullet Insulation Connector Monopole
Specifications Number of monopole holders: 3 Material : Al-6061 Specifications: Dimensions of monopole holder: outer diameter = 20mm inner diameter = 8mm length = 29 mm + 2mm (thickness of square base) length of square base = 25 mm
Requirements It is a fixture that holds the monopole on the satellite in the specified orientation . The major features of the holder are : 1. to provide connectivity to the monopole 2. to insulate it from the satellite body 3.to provide it with mechanical rigidity
Requirements (electrical) The monopole holder was designed keeping into mind the following constraints : The monopole had to be insulated from the satellite body while maintaining electrical connections with the feed point For the same reason we are using insulation i.e heat shrinkable tube between monopole and holder .
Why insulation ? Consider monopole as positive RF voltage reference and holder orsatellite body as ground. No insulation results in the following consequences The satellite body can start behaving like an antenna . In the absence of a ground plane , the radiation properties of the monopole would change .
Requirements (mechanical) Launch Loads – 15 g (9 g vertical ; 6 g horizontal) The design should prevent structural failure The sleeve transfers the load. The value of stress at the soldered joint reduces to 1/5th of initial without sleeve configuration. Epoxy is applied to make it rigid.
Theory It is a classical cantilever case. Yield stress (σV) = (σV =175 MPaapprox for Aluminium)
Load value 1/5th at the soldered joint is calculated from the dimensions of the monopole which are specified as follows : Effective cantilever length = 160mm( length of monopole antenna ) Diameter of monopole antenna = 6mm
ANSYS simulations The length of the sleeve was optimized by simulating the antenna in ANSYS by the Structures team
Why space grade materials ? 1.The material to be used should be able to last the temperature variations in space. 2. The design should be able to withstand launch loads . 3. Material of system components should not outgas.