receive and transmit antenna.

[caoquyen164]

hi everyone.
I am designing an antenna in CST. how can I made it be a receive or transmit antenna ? thanks alot.

 

[Aussie Susan]

There is not much of a difference between a transmit and receive antenna as far as the design is concerned. The key thing is that the transmit antenna must be as good a match with 'free space' as possible at the frequency involved whereas a receiving antenna can be just about anything.
Once you have worked out the frequency range (or ranges) you want to transmit, then ensure the antenna is resonant at those frequencies. When you test it, you should get a low SWR (i.e. the reflected power is low - if it is too high then you put a strain on the final amplifier and it not perform, shut down or blow, depending on how it was designed).
Susan

 

[caoquyen164]

thanks. but I'm in measurement project. It requires the antenna only can transmit or receive to reject noise of each other. can we simulator them ?

 

[volker@muehlhaus]

thanks. but I'm in measurement project. It requires the antenna only can transmit or receive to reject noise of each other.

As Aussie Susan already said, there is no difference between receive and transmit antennas. The only difference is if they are connected to a receiver or transmitter.

 

[FvM]

thanks. but I'm in measurement project. It requires the antenna only can transmit or receive to reject noise of each other. can we simulator them ?

The question isn't ver clear. Do you mean, you have separate transmitter and receiver antennas and want to minimize the crosstalk?

The coupling between both antennas can be determined in a simulation, but it's independent of transmitter or receiver function, due to antenna reciprocity.

 

[caoquyen164]

The question isn't ver clear. Do you mean, you have separate transmitter and receiver antennas and want to minimize the crosstalk?

The coupling between both antennas can be determined in a simulation, but it's independent of transmitter or receiver function, due to antenna reciprocity.

sr for my unclear question. yes. I mean that I have separate transmitter and receiver antennas.the wave transfer through media and come to receiver. normally, when an antenna is designed, it is both receiver and transmitter, right ?? but the system is in a small space. so if both antennas can be receiver or transmitter, they will affect to each other. we don't want this. so you said that we can set up them. can you show me more ?
P/S : I just learn CST for over a month. )

 

[volker@muehlhaus]

Your question is unclear again.

Do you ask about modelling the real, existing coupling in CST? Just model with 2 ports and study the S21 parameter.
Do you ask about minimizing the real, existing coupling? That design question is unrelated to CST.

 

[Aussie Susan]

Whatever signal you send from the transmitting antenna will be picked up by the receiving antenna - you can't stop that.
You can design the receiving antenna to be less sensitive to the transmitted frequency but this really requires that there is a significant difference in the transmitted and received frequencies.
If that is not the case - for example with a repeater where the Tx and Rx frequencies are often only a few kHz or MHz apart - then you need to put a filter into the Rx side that has a very sharp notch (i.e. high Q) at the Tx frequency.
I do not know about the tool you are using to simulate all of this, but basically it has little to do with the antenna design and more to do with the filter to need to add in.
Look up "repeater cavity filter" on Google for some ideas on this. Also search on 'desensing' which is the term used to describe the loss of reception sensitivity due to a nearby large signal source.
Susan

 

[volker@muehlhaus]

You can design the receiving antenna to be less sensitive to the transmitted frequency but this really requires that there is a significant difference in the transmitted and received frequencies.

Yeah, we don't know if receive and transmit frequencies are the same (e.g. radar system) or different (communication system).