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The formation of the first stars and galaxies during 'Cosmic Dawn' is thoughtto have imparted a faint signal onto the 21-cm spin temperature from atomicHydrogen gas in the early Universe. Observationally, an absorption featureshould be measurable as a frequency-dependence in the sky-averaged (i.e.global) temperature at meter wavelengths. This signal should be separable fromthe smooth -- but orders of magnitude brighter -- foregrounds by jointlyfitting a log-polynomial and absorption trough to radiometer spectra. Amajority of approaches to measure the global 21-cm signal use radiometersystems on dipole-like antennas. Here, we argue that beamforming-based methodsmay allow radio arrays to measure the global 21-cm signal. We simulate anend-to-end drift-scan observation of the radio sky at 50--100 MHz using azenith-phased array, and find that the complex sidelobe structure introduces asignificant frequency-dependent systematic. However, the {\lambda}/D evolutionof the beam width with frequency does not confound detection. We conclude thata beamformed array with a median sidelobe level around 50 dB below the mainbeam may offer an alternative method to measure the global 21-cm signal. Thislevel is achievable by arrays with O(10^5) antennas.

Beamforming approaches toward detecting the 21-cm global signal from Cosmic Dawn with radio array telescopes