# Coupler or Combiner?

1. ## Coupler or Combiner?

hi
could i use directional coupler instead of combiner?
i need to combine two signal but hasn't any combiner.
if i use coupler, what happen for signal? is that degrade?
freq=uhf.

tnx

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2. ## Re: Coupler or Combiner?

Originally Posted by mehdu
hi
could i use directional coupler instead of combiner?
i need to combine two signal but hasn't any combiner.
if i use coupler, what happen for signal? is that degrade?
freq=uhf.

tnx
you are possible using a quadrature hybrid coupler (a type of directional coupler) as a combiner at the cost of 3 dB attenuation at branches 2 and 3/ output at 1 port and isolation matched load at port 4 ( please refer to Pozar book: microwave engineering for more detail).

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3. ## Re: Coupler or Combiner?

In principle you can use a "standard" directional coupler, if you just want to mix two different signals, but depends from your application (f.i have you got some specific phase impairement requirement ?) and the maximum attenuation you can afford.
Take into account that the signal on the direct line will be attenuate by just some tenth of dB while that sent to the coupled line will be attenuated by the coupling factor. To equalize the attenuation you have to insert a fixed attenuator from the generator toward the direct line.

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4. ## Re: Coupler or Combiner?

Originally Posted by albbg
In principle you can use a "standard" directional coupler, if you just want to mix two different signals, but depends from your application (f.i have you got some specific phase impairement requirement ?) and the maximum attenuation you can afford.
Take into account that the signal on the direct line will be attenuate by just some tenth of dB while that sent to the coupled line will be attenuated by the coupling factor. To equalize the attenuation you have to insert a fixed attenuator from the generator toward the direct line.
i want combine two signal from signal generator.so i can adjust the level attenuated by coupling factor.

5. ## Re: Coupler or Combiner?

The directional coupler is a linear passive device, then the signals will not get distorted.

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