I saw the following sentence in a journal paper.
The base stations, users, and relays are each equipped with one antenna.
I'm sure it means that each of them is equipped with one antenna. However, I can't understand how the word 'each' is placed there in the sentence above. I've learned that 'each' acts as a determiner or a pronoun depending on the sentence. Hence, as far as I am concerned, it should be written as
Each of the base stations, users, and relays is equipped with one antenna.
The base stations, users, and relays are equipped with one antenna, respectively.
However, I've seen the structure of the first sentence several times. Accordingly, I felt there is a sentence structure or grammar that I don't know. Please explain how 'each' can be placed between be verb and past participle.