Salut guytoub,
I think these 2 papers ae valuable for you. The second one shows examples of 3 to 7-section designs.
Cohn: A class of broadband three-port TEM-mode hybrids (IEEE Trans MTT, Feb 1968)
Abstract—The three-port hyhrid considered in this paper is useful both as a power divider and power combiner. In the divider application, power entering the input port is split equally and with zero phase difference between the output ports. All ports are well matched and the output ports are highly isolated. The generalized form of the hyhrid circuit is a T junction followed by a multiplicity of cascaded pairs of TEM line lengths and interconnecting resistors. Due to symmetry, the resistors are decoupled from the inpnt port, but they serve an essential fnnction in providing ontput-port match and isolation. Each pair of lines and its associated resistor are referred to as a section. The one-section hybrid has been known and widely used, Its usable bandwidth is J,/j, = 1.44:1 for VSWR <1.22 and isolation >20 dB. This paper shows that additional sections can provide a large increase in bandwidth. Some of the examples treated are as follows: two sections, fJfl = 2, VSWR <1.11, isolation> 27 dB; four sections, f,/f, = 4, VSWR <1.10, isolation >26 dB; and seven sections, fq/f, = 10, VSWR <1.21, isolation> 19 dB. Exact design formulas are given for two-section hybrids, and approximate design formulas for three or more sections.
A GENERAL DESIGN FORMULA OF MULTI-SECTION POWER DIVIDER BASED ON SINGLY TERMINATED FILTER DESIGN THEORY
ABSTRACT: A novel design formula of multi-section power divider is derived to obtain wide isolation performance. The derived design formula is based on the singly terminated filter design theory. This paper presents several simulation and experimental results of multisection power divider to show validity of the proposed design formula. Experiments show excellent performance of multi section power divider with multi-octave isolation characteristic .
Regards
Z