Divider is simply dividing the signals as the words.
Divider is used to divide the signals from the filter or send the divided signal to antenna.
It divides the input signal to output port as a number of output port. The phase and signal in output ports are same, and only the power is divided. Therefore, it is called Power divider.
It varies a number of output ports, 2way, 3way 4way or 8way divider, based on the number of output port.
We will see the Wilkinson divider for better understanding as shown below.
drawing on Dra. 4-1. Impedance is 50Ω matched in RF, if characteristic impedance is Z0 = 50 Ω, the impedance of λ/4 transmission line is 70.7Ω, and the resistor which is set to get the secure the divider circuit reliability in the middle of output port, is 100Ω.
two drawings on Dra. 4-2 and Dra. 4-3, if the 0dBm of signal is given into the input port of power divider, -3dB of signal at each output port is supposed to get. Therefore, it is also named as -3dB power divider. Shall we check it out about the 4way and 8way power divider? 4way divider is that additional 2way divider is added at 2way divider which divided 1/2(-3dB) output power at each ports.
In short, 1/4(-6dB) of signal is output at each of 4 ports. 8way divider is as same as like dividers which are explained. Therefore, 2 way divider has typical -3dB(1/2) of insertion loss at each ports, 4 way divider has -6dB(1/4) of insertion loss at each ports and 8 way divider has -9dB(1/8) of insertion loss at each ports. So, when we talk about the insertion loss, you should think of the original insertion loss at each ports.
What if the impedance, one of two transmission lines, is changed in this Wilkinson power divider, what is going to happen? For example, if one transmission line is 70.7Ω and the other is 35Ω, are the same output powers at both ports?
Naturally, the more power is likely to flow into the low impedance port, and the less power is delivered to the high impedance port. The power of 70.7Ω and 35Ω would have 1:2 ratios. Ratio of output power can be adjusted by the engineer as this way at unequalled output power divider, this type is applied at in-building installation in wireless telecommunication system by integrators.
Divider is also called as splitter. They are the same products with different names. If the signal is sent to the 2 output ports and single signal comes out to the input port after 2 signals are combined, we call it as Combiner. If the two signals would have same frequency, the power is combined.
If the two input frequency are different from each other, the two signals are come out to 1 port as their frequency.
In other words, like these divider and combiner, their names can be changed based on how they work for their application. Based on their direction of input and output port, we can call them as divider or combiner..
When you choose the power divider, you should check the return loss and insertion loss as well as other RF products.
If you see the Wilkinson divider drawing as shown below on Dra. 4-10. Return loss is to be checked on S11, S22 and S33 as well, and all of value should be -20dB or less. As there are 2 output ports and the same signal, power should come out to output port, therefore S21 and S31 values should be considered. Besides, the value should be same as -3dB with a little more loss in transmission lines. Additionally there is one more important factor. There is the isolation between port No. 2 and No. 3. If the two output ports are not isolated each other and if divider is used as combiner, the signal from port No. 2 can across over port No. 3 when the signal is allowed to port No. 2 and 3. On the contrary, the signal from port No. 3 can across over port No. 2 as well. Normally isolation (S23, S32) should satisfy under -18dB.
Based upon this theory, a high power divider over 100Watt can be designed. Most of high power divider is used between the outdoor antenna and repeater in telecommunication system. You can see the variety of power divider at the following pages.