Antenna siting and licensing
Antenna siting and national frequency licensing are the longest-lead items in any ground segment, routinely running 12–18 months. Errors here delay launch, void insurance or strand a satellite with no legal path to communicate.
The licence is not a formality. It is a critical-path item.
Every ground station that transmits to or receives from a satellite operates under a national frequency assignment issued by the relevant telecommunications authority, coordinated internationally through the ITU Radio Regulations. That coordination process has mandatory notice periods: a coordination request filed under Article 9 of the Radio Regulations triggers a four-month window for affected administrations to raise objections, and those objections must be resolved before the assignment is recorded in the Master International Frequency Register. Filing late, or filing with an incomplete technical coordination file, does not pause the satellite programme. It pauses the legal right to operate the ground station.
The practical consequence is that frequency assignment work must begin before the antenna design is finalised, often before the satellite bus is selected. Programmes that treat licensing as a procurement task to be handled in the final six months routinely discover, at the worst possible moment, that a neighbouring administration has a legacy assignment in the same band at the same azimuth. Resolving that takes bilateral negotiation, not engineering.
Horizon masks: what the sky actually looks like from your site
A horizon mask is a 360-degree elevation profile of obstructions as seen from the antenna phase centre: terrain, buildings, trees, and any structure that will block the line of sight to a satellite at low elevation angles. It matters because low-elevation passes are where a polar-orbiting spacecraft first appears and last disappears, and those passes often carry the bulk of a contact window for a low-Earth orbit mission. A mask that clips the horizon at 5 degrees rather than 2 degrees can reduce usable contact time per pass by 20–40 percent depending on orbital inclination and site latitude.
Mask surveys are conducted with a combination of digital elevation models (SRTM or national equivalents at 1-arc-second resolution or better) and on-site optical measurement, because buildings and vegetation are absent from terrain models. The survey must also account for planned construction: a site that is clear today may be obstructed within the licence period. Programmes in rapidly developing peri-urban areas have been caught by this. The honest answer is that a rural or coastal site with a clean horizon to the north (for equatorial and mid-inclination orbits) or to both poles (for sun-synchronous missions) is worth more than a convenient urban rooftop, even accounting for the additional infrastructure cost.
RF interference surveys: the environment you inherit
Spectrum is shared. Before a dish is poured into concrete, a calibrated RF survey of the candidate site establishes the interference floor across the intended operating bands. For S-band TT&C this typically means 2025–2120 MHz uplink and 2200–2290 MHz downlink. X-band downlink sits in 8025–8400 MHz. Both ranges are used by terrestrial microwave links, radar systems and, in some jurisdictions, military allocations that do not appear in public frequency registers.
The survey instrument is a calibrated spectrum analyser with a directional antenna, swept across azimuth and elevation over multiple sessions at different times of day and week. Interference sources that are intermittent, such as weather radar or pulsed military emitters, will not appear in a single morning sweep. A minimum of 48 hours of continuous logging is standard practice for any site being considered for a primary mission-critical station. Sites near airports, naval facilities or broadcast towers require longer surveys and may simply be disqualifying regardless of other advantages.
Geotechnical and grid requirements: the civil engineering that nobody budgets
A 7-metre dish in wind loading conditions typical of an exposed coastal or highland site exerts substantial overturning moments on its foundation. Geotechnical investigation, including soil bearing-capacity tests and groundwater assessment, determines the foundation design. Expansive clay soils require deeper piles; permafrost sites introduce seasonal heave that can misalign a precision antenna over time. These are not exotic edge cases. Many of the nations most interested in sovereign space programmes have geologically challenging terrain.
Power is the other civil surprise. A ground station with active cooling, redundant UPS systems and a high-power uplink amplifier can draw 30–80 kW continuously. Grid connection at that level, with the reliability needed for mission-critical operations (typically N+1 generator backup), requires utility coordination that can itself take 6–12 months in areas where the distribution network is constrained. Satellite programmes that assume the ground station will simply plug into existing infrastructure at a government facility are frequently wrong.
Where the method fails, and what to do about it
Siting surveys are predictive. They cannot fully account for interference sources that are commissioned after the survey, for atmospheric multipath conditions that vary seasonally, or for political changes that alter a neighbouring administration's spectrum posture. A site that passes every technical test may still face objections during ITU coordination if a neighbouring administration chooses to use the process as a negotiating instrument rather than a technical one. This is not hypothetical; it has affected programmes in multiple regions.
The mitigation is sequencing and redundancy. Filing the ITU coordination request early, before the site is fully committed, preserves the option to shift to an alternative site without losing the filing date. Designing the ground segment with at least two geographically separated stations from the outset means that a single siting failure does not strand the mission. The cost of a second site is almost always less than the cost of a launch delay caused by a licensing impasse. Programmes that treat the ground segment as a single-point architecture to be optimised for cost tend to discover this the hard way.
What a complete siting and licensing package actually contains
A defensible siting submission to a national telecommunications authority includes: a horizon mask survey with supporting terrain data and on-site measurement records; an RF interference survey report with calibration certificates and time-stamped logging; a frequency coordination file prepared to ITU Appendix 4 format, covering the proposed emission designators, equivalent isotropically radiated power, antenna gain patterns and coordination distances; a geotechnical report; and a power and civil infrastructure plan. The ITU filing itself is submitted by the national administration, not by the operator directly, which means the programme must engage the relevant ministry early enough that the administration can act as sponsor.
Lead time from site selection to a recorded ITU assignment, assuming no objections are raised, is typically 12–18 months. With objections requiring bilateral resolution, 24 months is not unusual. Programmes that launch on a 36-month build schedule and begin siting work at month 18 are building in a structural delay. The ground segment is not the glamorous half of a space programme, but it is the half that determines whether the satellite can legally speak.
Engineering parameters
| ITU coordination lead time (no objections) | 12–18 months from filing to MIFR recording |
| ITU coordination lead time (with bilateral objections) | 18–36 months; politically variable |
| Horizon mask survey accuracy | ±0.5° elevation with combined DEM and optical method |
| RF interference survey minimum duration | 48 hours continuous logging; longer near radar or military emitters |
| Typical continuous power draw (mission-critical station) | 30–80 kW including cooling, UPS and uplink amplifier |
| Geotechnical investigation scope | Soil bearing capacity, groundwater, seismic zone, seasonal heave assessment |
| Minimum site clearance from horizon obstruction (LEO TT&C) | 2–5° elevation mask; lower is better for polar passes |
| Grid reliability requirement (mission-critical) | N+1 generator backup; typically 99.9% uptime target |
One contract, one accountable engineer
Commissioned as one programme, not a stack of contracts: spacecraft, launch, ground segment, mission control, training and handover are priced together. Source-access terms and audit rights are agreed in writing before signature. Request a siting and licensing assessment.