The Electromagnetically Isolated Global Signal Estimation Platform (EIGSEP) is a new instrument designed to measure the global 21-cm signal from Cosmic Dawn and the Epoch of Reionization, redshifted to frequencies below 250 MHz. To reduce spectral structure in the antenna beam associated with ground scattering, EIGSEP uses a shaped bowtie antenna suspended in a canyon 100 m above the ground. We describe the current system design of EIGSEP, including the rotating antenna platform, a transmitter antenna to characterise the beam of the bowtie antenna, and auxiliary ground antennas. We then discuss the EIGSEP calibration scheme, which incorporates traditional Dicke switching in the receiver, and novel approaches that include beam mapping, beam modulation, and interferometric cross-correlation. The instrument has been deployed near Marjum Pass, Utah, for testing and initial data collection. We discuss the site characteristics and present initial field measurements.
@article{arxiv.2602.02661,
title = {The Electromagnetically Isolated Global Signal Estimation Platform (EIGSEP)},
author = {Christian H. Bye and David R. DeBoer and Matt Dexter and Aaron Ewall-Wice and Adam Fahs and Pranav Karthik and Komal Kaur and Bahram Khalichi and Wei Liu and Raul A. Monsalve and Aaron R. Parsons and Reid Parsons and Richard R. Rodriguez and Richard J. Saeed and Charlie G. Tolley and Dominic Vazquez and Dirk Wright},
journal= {arXiv preprint arXiv:2602.02661},
year = {2026}
}