  We demonstrate a scheme to realize high-efficiency entanglement of two
microwave fields in a dual opto-magnomechanical system. The magnon mode
simultaneously couples with the microwave cavity mode and phonon mode via
magnetic dipole interaction and magnetostrictive interaction, respectively.
Meanwhile, the phonon mode couples with the optical cavity mode via radiation
pressure. Each magnon mode and optical cavity mode adopts a strong red detuning
driving field to activate the beam splitter interaction. Therefore, the
entangled state generated by the injected two-mode squeezed light in optical
cavities can be eventually transferred into two microwave cavities. A
stationary entanglement E_{a_{1}a_{2}}=0.54 is obtained when the input two-mode
squeezed optical field has a squeezing parameter r=1. The entanglement
E_{a_{1}a_{2}} increases as the squeezing parameter r increases, and it shows
the flexible tunability of the system. Meanwhile, the entanglement survives up
to an environmental temperature about 385 mK, which shows high robustness of
the scheme. The proposed scheme provides a new mechanism to generate entangled
microwave fields via magnons, which enables the degree of the prepared
microwave entanglement to a more massive scale. Our result is useful for
applications which require high entanglement of microwave fields like quantum
radar, quantum navigation, quantum teleportation, quantum wireless fidelity
(Wi-Fi) network, etc.
