Fig 1.
The three-dimensional (3D) structure of the proposed TTPD.
This TTPD is excited by 50 Ω microstrip feeding line. The ground is constructed completely by a metal and the applied substrate is the Rogers 4350B with the relative permittivity of 3.48, the thickness h of 0.762 mm and the loss tangent of 0.0037. The length of the FSS in output path-2 and output path-3 are marked in the picture, wm is the width of the 50 Ω microstrip feeding lines and the stubs in the FSS, w2 and w3 (L2 and L3) are the width (length) of the MS in the two output paths, dw is the diameter of the via holes. wm = 1.7 mm, w2 = 0.9 mm, w3 = 0.1 mm, L2 = 14.9 mm, L3 = 48.6 mm, dw = 1.2 mm.
Fig 2.
(a) Each path from the input port to the output port includes the LN shown as Transformer 2 and Transformer 3 in this picture. R1 (R2 and R3) is the terminal impedance of the input (output) port, R2i and R3i are the equivalent input impedance calculated in the direction from the input to the output in path-2 and path-3 at each specific frequency fi. The MS and the FSS of the L-type Transformer 2 (Transformer 3) are respectively expressed by its ABCD-matrix and the equivalent input impedance jX2i (jX3i) in (b) and (c).
Fig 3.
The layout of the proposed LN and the ideal simulation results of the TTPD.
(a) The LN is made up of six transmission lines with its ideal electrical parameters. In output path-2: Z2 = 69.83 Ω, E2 = 28.7 @ 1 GHz, E21 = 103.2 @ 1 GHz, E22 = 141.4 @ 1.6 GHz, E23 = 178.5 @ 2.35 GHz. In output path-3: Z3 = 138.2 Ω, E3 = 88.07 @ 1 GHz, E31 = 90.3 @ 1 GHz, E32 = 138.4 @ 1.6 GHz, E33 = 41.8 @ 2.35 GHz. The input terminal impedance R1 = 50 Ω and the output terminal impedances R2 = 50 Ω, R3 = 68.6 Ω. λ1 and λ2 are the wavelengths of 1 GHz and 1.6 GHz. (b) The simulation results of the TTPD with the ideal electrical parameters in (a).
Fig 4.
The ideal simulation results of the two comparative examples of the TTPD.
(a) Comparative example with same power division ratio and different operating frequency (1 GHz, 2.35 GHz, 3.5 GHz). (b) Comparative example with different power division ratio (0 dB, -3.5 dB, -5.8 dB) and same operating frequency.
Fig 5.
The picture of the TTPD on PCB.
The photo of the TTPD is on PCB with the approximate size of 70x150 mm2.
Fig 6.
The TTPD with the complete tri-band performance.
The simulated and measured input reflection coefficient |S11| and the three sub-graphs extracted at 1 GHz, 1.6 GHz, and 2.35 GHz are given.
Fig 7.
The insertion loss responses of the TTPD.
The simulated and measured coefficient |S21|, |S31| and the difference of |S21|-|S31| are given. The three sub-graphs extracted at three frequency points are given.
Fig 8.
The isolation responses of the TTPD.
The simulated and measured coefficient |S23| are presented.
Table 1.
Comparison of proposed power divider with existing ones.