title: First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers.
abstract: We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the Cosmic-Ray Observation via Microwave Emission experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3×10^{16}  eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarized emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at E≥10^{17}  eV.
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Smída
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Werner
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Engel
authors.affiliation: Universidad Michoacana, Instituto de Física y Matemáticas, 58040 Morelia, Mexico.
authors.forename: J C
authors.initials: JC
authors.lastname: Arteaga-Velázquez
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Bekk
authors.affiliation: Università di Torino and Sezione INFN, 10125 Torino, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Bertaina
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Blümer
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Bozdog
authors.affiliation: National Institute of Physics and Nuclear Engineering, 76900 Bucharest, Romania.
authors.forename: I M
authors.initials: IM
authors.lastname: Brancus
authors.affiliation: Università di Torino and Sezione INFN, 10125 Torino, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Chiavassa
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Cossavella
authors.affiliation: Università di Torino and Sezione INFN, 10125 Torino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Di Pierro
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Doll
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Fuchs
authors.affiliation: Bergische Universität Wuppertal, 42097 Wuppertal, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Fuhrmann
authors.affiliation: Department of Physics, Siegen University, 57072 Germany.
authors.forename: C
authors.initials: C
authors.lastname: Grupen
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Haungs
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Heck
authors.affiliation: Department of Astrophysics, Radboud University Nijmegen, 6500 The Netherlands.
authors.forename: J R
authors.initials: JR
authors.lastname: Hörandel
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Huber
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Huege
authors.affiliation: Bergische Universität Wuppertal, 42097 Wuppertal, Germany.
authors.forename: K-H
authors.initials: KH
authors.lastname: Kampert
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Kang
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Klages
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kleifges
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Krömer
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Link
authors.affiliation: Department of Astrophysics, National Centre for Nuclear Research, 90-950 Łódź, Poland.
authors.forename: P
authors.initials: P
authors.lastname: Luczak
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ludwig
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Mathes
authors.affiliation: Bergische Universität Wuppertal, 42097 Wuppertal, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Mathys
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Mayer
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Melissas
authors.affiliation: Osservatorio Astrofisico di Torino, INAF 10133, Torino, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Morello
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Neunteufel
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Oehlschläger
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Palmieri
authors.affiliation: Institute of Nuclear Physics PAN, 31-342 Krakow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Pekala
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Pierog
authors.affiliation: Bergische Universität Wuppertal, 42097 Wuppertal, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rautenberg
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Rebel
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Riegel
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Roth
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Salamida
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schieler
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schoo
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: F G
authors.initials: FG
authors.lastname: Schröder
authors.affiliation: Department of Physics, University of Bucharest, 76900 Bucharest, Romania.
authors.forename: O
authors.initials: O
authors.lastname: Sima
authors.affiliation: Institute of Nuclear Physics PAN, 31-342 Krakow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Stasielak
authors.affiliation: National Institute of Physics and Nuclear Engineering, 76900 Bucharest, Romania.
authors.forename: G
authors.initials: G
authors.lastname: Toma
authors.affiliation: Osservatorio Astrofisico di Torino, INAF 10133, Torino, Italy.
authors.forename: G C
authors.initials: GC
authors.lastname: Trinchero
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Unger
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Weber
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Weindl
authors.affiliation: Institute of Nuclear Physics PAN, 31-342 Krakow, Poland.
authors.forename: H
authors.initials: H
authors.lastname: Wilczyński
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Will
authors.affiliation: Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wochele
authors.affiliation: Department of Astrophysics, National Centre for Nuclear Research, 90-950 Łódź, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Zabierowski