Tapered Hybrid Junction > Analysis Page:

   In this page you can obtain S parameters of tapered hybrid junction at the center frequency and you can obtain the plot of those S parameters versus frequency. In this page you will see three different panels and only the one of them needs to be filled by user. At the very top and left part of the page you will see that panel that needs to be filled by user. You can see the image of that panel below.

  You will see there 5 textfields that user should fill his/her numbers. In order to understand which variables are asked for those textfields user should look at the image of the tapered hybrid junction at the right-top of the page. There you will see an image like below.

  As you see in that image Zo asked at the above panel is the characteristic impedance of the feedlines that carries signals to the network. Zr is the impedance value of the tapered hybrid just at the beginning of the port 2 and 4 looking into inside the networka and  it is called as in-between impedance throughout this toolkit. In the even mode of the network that Zr will increase up to Zr/k at the length L and just after the length L  Zr/k will suddenly drop to Zr again an it will stay unchanged up to port 1 and 3. In the odd mode of the network that Zr will decrease up to Zr*k at the length L and just after the L Zr*k will suddenly go up to Zr again an it will stay unchanged up to port 1 and 3 ( you can find detalied info at the Theory page for tapered hybrid junction). As you see the tapered hybrid junction have copuled lines between 0<z<L, take the beginning of port 4 as z=0, by the coupling factor k and uncoupled lines between L<z<2L.

    Then just write the coupling factor k and half-legth of tapered hybrid L, interms of cm, into correspondind textfields that you see above. However make sure that you entered a number between 0 and 1 for k to obtain significant results. Otherwise you will be warned about that. And finally write the frequency that your design circuit operate at, ie design or center frequency, in the textfield labeled as fo.

 After you all complete the writing of those variables into corresponding textfield you can obtain the S parameters of the tapered hybrid at the center frequency by clicking on the button labeled as Execute [S]@fo (see the image below) . Whenever you click on that button, unless you enter an invalid number for k, you will immeaditely see the S parameters in the textfields below the execute button. You will always see a number different than zero for s11 if you enter different numbers for Zo and Zr (i.e. if Zr is not equal to Zo). If you enter the same number for both Zo and Zr you will see that s11=0, meaning matched port.Thus remember that equality of Zo and Zr gives us matched port.

  After you obtain S parameters at the center frequency you can obtain plots of those parameters or it is also possible to obtain them  after completing the filling of the textfields at the top-left panel. All you have to do to obatin the plot of any parameter is to just mark the radiobutton labeled as the parameter to be plotted and then to click on the button below that radibuttons labeled as Plot [S]ij vs. f  (see the image below). It is also possible for user to determine the range of the x axis of the plot by entering the desired numbers as the multiples of the center frequency into the textfields above those radiobuttons. As you see there is not s14 parameter overt there since it is always equal to zero due to the structure of the tapered hybrid junction.

     Then you might have a plot something like the below image. Remember that x axis is composed of numbers as the multiples of center frequency fo and y axis is in dB scale. The y axis of the plot is [S]ij in dB scale, i.e logarithmic scale, that is for example in the plot of s11 what you see actually is the plot of 10xlog(|s11|) (|s11| is absolute value of s11). The y axis is ranged between -40 and 0 since S parameters vary between -1 and 1. the extends of x axis is changable for now but y axis not.
 
 

  Finally you can turn to tapered hybrid junction menu to make another operation by clicking the To Menu button at the bottom the page.