An Ultra Compact Microstrip Branch Line Coupler with Wide Stopband Using LCL Filter and Meandered Stubs for Microwave Applications

Round 1

Reviewer 1 Report

1.It is important to highlight key contributions and innovation, especially theoretical and technological innovation.

 2. Please add the test setup and condition for your design. 

3. Except for S parameters, is there another parameter can be measured?

 4. There is no any theoretical derivation and calculation, please add this??

 5. What is the detail application occasion for your design??

 6. Please revise the reference carefully, it is too non-standard and uniform, there are many mistakes in the references.

 7. The overall logic and writing should be revised again. It is should be write as a design paper . 

1.It is important to highlight key contributions and innovation, especially theoretical and technological innovation.

2. Please revise the reference carefully, it is too non-standard and uniform, there are many mistakes in the references.

 3. The overall logic and writing should be revised again. It is should be write as a design paper . 

Author Response

Please see the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

This is an interesting and partly novel contribution in the area of compact branch-line couplers. The text could be improved since is here and there a little confusing or incomplete:

- in the Introduction the "large size" of the branch-line coupler is mentioned, remarking that this is due to the "applied four large branches in the structure". Maybe is better to say that the length of the four lines is lambda/4 at centerband, which makes the size inconvenient at the design frequency.

- Always in the Introduction the author mention "coupling lines" as a way to suppress harmonics, do they mean "coupled lines"? Also, the comment "the presented coupler etc." immediately after the sentence on harmonic suppression is confusing since it refers to the return loss. Please clarify.

- Some figures are redundant, like Fig. 1 (the layout of a conventional branch-line coupler is well known) but also the layouts in Fig. 3 and Fig. 4 (the vertical and horizontal sides have the same topology already reported in Fig. 2.

- In Fig.6 the 10.4 mm etc. length of the branches is taking into account the size of the lumped elements? is that size derived from the experimental realization?

- The proposed technique makes use of a mixup of lumped and distributed elements, I wonder why a purely lumped realization were possible (as it is in the case of a lumped branch-line without harmonic suppression). The frequency should be low enough to allow for this and the size would be even smaller (I surmise) than in the proposed design. Please comment.

- Some more details on the simulation tools used would be welcome, in particular with respect to the simulation of the meander line stubs, was that simply a stub having the total length of the meander or was the coupling between sides considered?

See Comments to authors, the text is understandable but can be improved.

Author Response

Please see the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The refernernces  still need to be modified as uniform.   

 

English  shouled be revised again.