Begin with the counterintuitive idea: in radar, geometry is a sensor. A monostatic radar transmits and receives from the same place and is limited by that single vantage. A multistatic system separates transmitter and receiver across multiple platforms, and the spatial diversity itself becomes information, revealing structure a single look would miss.

GeoOptics' grant US10718869B2 (inventor Thomas Patrick Yunck), classified in G01S 19/22 (satellite-based positioning and signal processing), claims a symmetrical multistatic radar constellation for Earth observation. The word symmetrical is doing real work: it points to a deliberately arranged geometry where the satellites' relative positions are part of the measurement design.

“A constellation of satellites and associated methods for Earth Observation are disclosed.”— U.S. Patent No. 10,718,869 source

The independent method claim is specific about how the geometry is wired. It describes operating a constellation of at least four satellites in which each satellite individually generates at least one sounding signal, transmitting a set of at least four sounding signals toward the Earth. The constellation then detects a set of at least four forward scatter signals, and the claim insists on a precise pairing rule: each forward-scatter signal uniquely corresponds to one of the sounding signals to form a set of sounding pairs, and within every pair the signal is transmitted and received by different satellites. That last condition is the heart of a multistatic design. A monostatic look is excluded by definition; every measurement is a bistatic baseline between two distinct spacecraft.

The claim then requires that each satellite individually houses its own signal analyzer, so the set of at least four forward-scatter signals is analyzed by a set of at least four signal analyzers distributed across the formation rather than relayed to a single processing node. The Earth observations are derived from the resulting set of data. The symmetry, in other words, is not decorative; it is the condition that lets every satellite serve simultaneously as an illuminator for its neighbors and as a receiver for the signals they send back, so the same four-spacecraft formation yields a dense web of crossing transmit-receive paths.

Forward scatter is the term that pins down the physics. Conventional imaging radar leans on backscatter, the energy reflected back toward the transmitter. Forward-scatter geometry instead reads the energy that continues onward past the target toward a receiver on the far side of the path. That regime is sensitive to features and conditions a backscatter look handles poorly, and capturing it requires exactly the separated transmitter-and-receiver arrangement the claim builds in. Distributing the sounding sources and the analyzers across the constellation is what makes the forward-scatter measurement possible at all.

The mechanism's payoff is sensitivity and coverage from cheaper parts. Rather than build one enormous, expensive radar satellite, you distribute the function across several smaller ones and let the formation geometry recover performance. Each spacecraft carries a modest sounding source and analyzer; the resolving power comes from the number of distinct cross-paths the formation creates, which grows quickly with the number of satellites. It is the same distributed-systems instinct that reshaped communications constellations, applied to sensing.

This sits at the crossover of B64G constellation design and G01S radar, the corner where Earth-observation innovation has clustered. It rhymes with later multistatic and formation-based remote-sensing work, such as the 2023 Spacety formation-based constellation grant, that pushes the same distributed-sensing thesis further.

The dependent claims show how much the same formation is meant to do, and they read as a catalogue of radar modes wrung from one architecture. Claim 2 specifies that the set of data captured for each forward-scatter signal includes its phase, amplitude, delay, frequency, and polarization, and that deriving the observations includes both scatterometry, which reads surface roughness and scattering properties, and altimetry, which reads height. A single multistatic pass, in other words, is meant to yield several distinct geophysical products rather than one image. Further claims layer on coherent modes: by having each satellite generate at least two time-gated sounding signals using an onboard oscillator, the constellation can perform synthetic aperture radar derivations, and with at least two sets of time-gated signals it reaches interferometric synthetic aperture radar, the technique that measures fine surface deformation by comparing phase between looks.

The signal-separation problem inherent to so many simultaneous transmitters is addressed directly. Claim 5 encodes each sounding signal with a unique pseudonoise code and pairs it with matched PN-code signal analyzers, so each receiver can pick out exactly the soundings it is meant to hear from the chorus of overlapping transmissions, the same code-division logic that lets many GPS satellites share one band. The constellation is also not limited to forward scatter alone; a further claim adds detection of back-scatter signals that form monostatic sounding pairs, letting the same hardware collect conventional reflected returns alongside the forward-scatter ones. And the geometry claims make the symmetry concrete, describing a nonuniform axial spacing arranged so that subsets of satellites are equidistant from a single shared reflection point on the Earth, with the spacing shifted between passes to walk that shared reflection point across the surface.

As always, the document defines the design, not the deployment. A symmetrical multistatic constellation is demanding to fly, because the geometry that makes it work also has to be maintained against orbital perturbations. The pairing rule that gives every measurement its bistatic baseline assumes the satellites hold known relative positions; drift in the formation turns a clean sounding pair into an uncalibrated one. The patent tells you the intended capability, down to the four-satellite minimum and the per-satellite analyzer; station-keeping and calibration decide whether the picture actually resolves.