Miniutarizing the Size of Microwave Circuits. Meander Line Trick

It’s often desirable to shrink the size of the circuits. Microwave circuits sometimes take a lot of space especially at relatively low frequencies. There are few methods to reduce the size of the circuit. This might inlcude changing the topology, dialectric material or topology. In this blog post, we are going to show how using meander lines can reduce the circuits’ size by not changing a lot in your circuit.

The key here is to understand the two lines in figure.1 are very similar in terms of their electrical characteristics (black area represents dielectric and vlue area represents the copper area in figure.1). It’s due to the fact that their total lengths are pretty close to each other (6mm and 5.95mm).  Figure.2 shows their S-parameters S11 and S22.

Figure.1 : The straight line is 6mm long and the meander line’s total electrical length is 1.5+1.725+1.725+1 = 5.95m.

Figure.2 : S11 shows the s-parameters for the straight line and S22 shows the s-parameters for meander line. Notice how close thier s-parameters are.

As it’s seen in figure.1 the circuit’s size has decreased with very small change in electrical characteristics.

Practically, They can’t be exaclty the same, but as you see they are pretty close. The bends in the meander line are not regular transmission lines and because of that the characteristics of the meander line deviates from the straight line slightly.

When using meander line trick to shrink your circuit, make sure that t

he line segments are not very close to each other. When the segments are very close to each other fields from one segment to other coupled showing very different electrical charateristics.