Explanation of 4/2 time signature
In the article time signature, this is explained that:
- the top number indicates the number of time units in a measure (bar 
- the bottom number determines the unit of time.
We can visually translate 

That is to say that there are 4 half notes (minims 

1 half note 

2 quarter notes 

4 eighth notes 

and so on...
Examples found in famous works
Glareanus' Dodecachordon, Josquin des Prés
Here is an example of a 4/2 time signature, with the musical work Glareanus' Dodecachordon from the french composer Josquin des Prés (1450-1521), for two tenor recorders.
4/2 time signature is classified as simple quadruple meter: There are 4 beats per measure and each beat is divided by 2. The value of one beat is 

You will notice the use of the note value called double-whole note (breve 
Franz Schubert, Impromptu n°3
Franz Schubert's Impromptu n°3 in G flat major has two time signatures 



Royalty free sound sample recorded by Chiara Bertoglio (CC BY 3.0 license, source).



This is very helpful
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