Thinned-Array Curse
9 days ago
- #power transmission
- #antenna arrays
- #electromagnetic theory
- The thinned-array curse is a theorem in electromagnetic theory of antennas.
- It states that a transmitting antenna synthesized from a coherent phased array of smaller, spaced-apart apertures will have a smaller minimum beam spot size but reduced power in the main lobe.
- The power density in the beam remains constant despite the reduced power in the main lobe.
- The term's origin is unclear, but Robert L. Forward cites its use in unpublished Hughes Research Laboratories reports from 1976.
- An example illustrates that separating sub-apertures reduces the spot size on the ground but keeps power density unchanged.
- The theorem implies that only a fraction of the radiated power reaches the target, with the rest lost in side lobes.
- The thinned array curse applies only to mutually coherent sources.
- Consequences include limitations for power transmitters and implications for microwave power transmission and solar power satellites.
- The curse suggests that reducing receiver size via phased beams from small satellites is not feasible.
- Robert Forward's paper discusses the curse's implications for interstellar travel using laser-pushed lightsails.