Below the microwave bands, using wire transformers, it is easier to make 180 degree couplers than quadrature couplers.

In the microwave bands, using coupled transmission lines, it is easier to make quadrature couplers than 180 degree couplers.

Because of this, I marveled at the very broadband, low frequency, quadrature couplers from Merrimac, Inc.  It was many years before I learned about the patents by Joeseph D. Cappucci.