L2-COM-ANT ESSENTIAL COMMAND CONTROL Level 2 · hardware

Antenna Systems

High-Gain Dish, Omnidirectional, and Phased Array Antenna Suite

The antenna suite provides the physical radio-frequency interface between settlement transceivers and free space, combining a parabolic dish of at least 1.5 meters for Earth links, omnidirectional antennas for local mesh and beacons, and an electronically steered phased array. Operating across UHF, S-band, X-band, and Ka-band, the hardware must sustain pointing accuracy within 0.1 degrees. Maintaining this precision is challenged by extreme lunar temperature swings that induce thermal distortion across reflectors, electrostatic deposition of abrasive regolith onto aperture surfaces, and vacuum conditions that require two-axis gimbal mechanisms to track Earth without lubricant outgassing while anchored to stable foundations.

Suite of antenna systems including high-gain parabolic dish for Earth link, omnidirectional antennas for local mesh and beacon, and phased array for flexible beam steering.

Purpose

Provide the RF apertures needed by all communication functions, matching antenna gain and coverage patterns to each link's requirements.

Context

Physical RF interface between the Ark's transceivers and free space; must handle Earth-pointing, local coverage, and emergency omnidirectional transmission with minimal maintenance.

Principles

▸High-gain dish maximizes Earth link margin at minimum transmit power
▸Omnidirectional antennas ensure coverage regardless of orientation
▸Phased arrays enable electronic beam steering without mechanical gimbals
▸Redundant antenna paths for fault tolerance

Typical implementations

▸1-3m parabolic dish with two-axis gimbal for Earth tracking
▸Patch or monopole omnidirectional antennas for mesh and beacon
▸Electronically steered phased array as backup Earth link
▸Multi-band feed systems for S/X/Ka operation on single dish

Lunar considerations

▸Lunar dust abrasion and electrostatic deposition on reflector surfaces
▸Thermal distortion of dish from extreme temperature swings
▸Gimbal mechanisms must operate in vacuum without lubricant outgassing
▸Foundation must be stable to maintain pointing accuracy

Specifications

Functional

primary function	Radiate and receive RF signals with appropriate gain patterns for Earth, local, and emergency communication links
inputs	RF signals from transceivers, pointing commands from CDH
outputs	radiated RF beams toward Earth or local area, received RF signals to transceivers
high gain dish diameter m	>=1.5
pointing accuracy deg	<=0.1
frequency bands	S-band, X-band, Ka-band, UHF

Physical

materials	carbon fiber composite reflector, aluminum structure, vacuum-rated gimbal bearings
vacuum	True
dust	lunar regolith
uv exposure	True

Operational

thermal range c	-173, 127
lifetime years	100

Interfaces

Provides

→Earth Communication Linkhigh_gain_rf_pathessential
High-gain antenna aperture for Earth link transceivers
→Local Mesh Networkomni_rf_pathessential
Omnidirectional antenna coverage for mesh radios
→Emergency Beaconbeacon_antennacritical
Omnidirectional antenna for emergency beacon

Requires

←L1-EPSelectrical_poweressential
Power for gimbal motors and phased array electronics
←Command & Data Handlingpointing_commandsessential
Antenna pointing directives based on Earth ephemeris
←Primary Structuremounting_platformessential
Stable structural mount for dish and arrays