The circumference of the ring should be 6/4*lambda. One half will be 3 quarterwave sections, the other half will be a single 3/4-wavelength section. Use a transmission line calculator to find the length of a quarterwave line; that will be the arc-length for one section, which will take up 360/6 = 60 degrees. The 3/4-wavelength side will sweep out 180 degrees.
A little bit of math should get you any other values that you are looking for. Recall C = 2*pi*radius, and arc length = C*angle/360.
enjunear sir,
If three sides angle is equal to 60 degees, what will be radius of curvature. If one side is equal to 180 degrees, what will be the radius of curvature.
---------- Post added at 12:12 ---------- Previous post was at 12:11 ----------
enjunear sir,
If three sides angle is equal to 60 degees, what will be radius of curvature. If one side is equal to 180 degrees, what will be the radius of curvature.
---------- Post added at 13:14 ---------- Previous post was at 12:12 ----------
:?::| how to find the radius of curvature for the three 60 degrees angles and one 180 degree angle t
As I stated before, the three 60 degree sections need to be one-quarter of a wavelength long at your frequency of interest (center frequency). Use a microstrip calculator (or equations from a microwave circuit design textbook) to find the length of a quarterwave line.
If you are trying to make a ring hybrid (a.k.a. Rat Race), this should not be this difficult (i.e. your thinking too hard). To construct the ring, take 4 MCURVEs, set them to have the same radius (just pick a number at random, to get started). Make three of them angle=60 deg, and one of them angle=180 deg. Connect them end-to-end, so they make a complete circle. At each of the connection points, add an MLIN that is rotated such that it's perpendicular to the arc (so it sticks out, and points away from the center of the ring).
Once you have the circle and input/output lines, change the radii of the ring sections to all be the same value, so the circle remains a nice, connected circle. Then, using LineCalc, determine the length of each 60 degree MCURVE such that it's arc length equals 1/4th of a wavelength (for linecalc: electrical length = 90 degrees). Also, make thering section widths such that they have a characteristic impedance of 1.414*Z0. If Z0 = 50 ohms, then the circle must have lines that are ~70.7 ohms. All of the radial input & output lines will have a width congruent with Z0 = 50 ohms.
Enjunear Sir,
I tried as you said in the previous replay,and followed each and every step as said sir. I am getting little extension in the one of the curvature. I couldn't find out , where I am doing mistake and I designed the rat race coupler for the following values
f= 3GHz, Z0= 50 Ohms, H=1.6mm, T=0.036mm, relative permitivity =4.4.
I have calculated and substituted the "R" value as you mentioned formula,the formula and obtained value as follows
ArcLength =2 PI R C/360 , where C is the central angle of the arc in degree
R is the radius of the arc.
ArcLength = 2*3.14 R 60/360
14.0083 =2*3.14 R 1/6
R = 13.3837261.
The above 'R' value substituted as 'R' value in MCURVE, I am getting the little extension one leg ,and could find it mistake. Here with I am attaching the schematic, layout and related document for the RAT RACE COUPLER . Please see sir and give me descriptively , where I am doing the mistake, what value need to substitute to get the desired ring shape. Please help me sir.
Enjunear Sir,
I tried as you said in the previous replay,and followed each and every step as said sir. I am getting little extension in the one of the curvature. I couldn't find out , where I am doing mistake and I designed the rat race coupler for the following values
f= 3GHz, Z0= 50 Ohms, H=1.6mm, T=0.036mm, relative permitivity =4.4.
I have calculated and substituted the "R" value as you mentioned formula,the formula and obtained value as follows
ArcLength =2 PI R C/360 , where C is the central angle of the arc in degree
R is the radius of the arc.
ArcLength = 2*3.14 R 60/360
14.0083 =2*3.14 R 1/6
R = 13.3837261.
The above 'R' value substituted as 'R' value in MCURVE, I am getting the little extension one leg ,and could find it mistake. Here with I am attaching the schematic, layout and related document for the RAT RACE COUPLER . Please see sir and give me descriptively , where I am doing the mistake, what value need to substitute to get the desired ring shape. Please help me sir.
Enjunear already answered your question. the problem is the TEE which you placed between the MCURVE's.
Another alternative is to draw your ratrace on an EM Planar simulator.
Since you already have the dimensions required from your calculations. Just make two circles, one with a radius equal to [R+(microstrip width)/2], the other with [R-(microstrip width)/2], subtract the smaller from the bigger, then make 4 microstrip lines, and attach them at 0deg, 60deg, 120deg, and 180 deg wrt to an arbitrary point on your circle. then just put the ports and simulate.
This should be obvious, why you're not lining up... you're adding length by sticking TEE's in between the arcs. If you remove the TEEs, then the circle should be perfect, right?
That works indeed. The problem is that the electrical model for the T-junction is missing now. Nice layout if we set the correct direction for the feedlines, but electrical results are not quite correct.
The better alternative is to include the T-junctions. One "simple & stupid" method would be to also use 3 * 60° segments, and insert line segments with L=w50 which is the equivalent length of the T-junction. Finally, reduce the radius by all that extra length, so that we have R'=R - (6*w50)/(2*pi)
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