Kanwalpreet Kaur Communication subsystem & Integration subsystem

Monopole Insulation Bullet Connector Monopole Holder (Exploded View, Internal)

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

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

The monopole holder was designed keeping into mind the following constraints : 1. 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.

Consider monopole as positive RF voltage reference and holder or satellite body as ground. No insulation results in the following consequences a) The satellite body can start behaving like an antenna. a) In the absence of a ground plane, the radiation properties of the monopole would change.

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 1/5 th of initial without sleeve configuration. Epoxy is applied to make it rigid.

Yield stress (σ V ) = (σ V =175 MPa approx for Aluminium ) It is a classical cantilever case.

Load value 1/5 th 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 Length of Sleeve (cm) Max. Stress on Sleeve (MPa) Max. stress on Antenna (MPa) The length of the sleeve was optimized by simulating the antenna in ANSYS by the Structures team

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.