Since 1/4 Transmission Line hybrids are too large in the frequencies up to 2 GHz (more than 10mm long for narrowband) and cannot be used in mobile phone. So I want to find an replacement (the best is for a wideband from 700 MHz to 2.1 GHz, but narrowband is also ok) with a much smaller size.
Does anyone has idea, which company has such kind of products.
I think you need only SMT device. Check Murata, Toko, TDK, Kyocera, may be Soshin. Such device can be realized on high quality ceramic with high dielectric constant in order to minimize dimensions. But there will be another problem: manufacturing repeatability which depends on accuracy of the process. If they have suitable ceramic and very accurate process like microlitography, they have a chance to make it for you.
I think S. H. is correct. I recall there is an extensive line of these and they may be small enough.
Modern marketing with all these Cute Names sure can make it difficult to find something. For example, I have yet to find a turbocharger on a computer but they sure have a bunch of turbo stuff anyway.