Hi,
I simulated an antenna with a matching network. Now to calculate the antenna range using Friis equation I need to know the losses due to the matching network.
Can anybody suggest how can I find the losses due to the matching network? I prefer to use software.
There are two components. Power loss due to power reflected back to the source and absorbed by the source (1-|S11|²) and loss in the matching circuit itself due to dissipation by the non-ideal reactive components.
It can be done with simulation. You need to simulate your matching circuit separately with input and output ports loaded to the real impedance. Usually, the matching circuit's loss is not significant and the inaccuracy of the Friis equation may be much bigger than the error from not accounting for this loss.
I agree with Pieter Willem Van der Walt . Alternatively in HFSS if you do a far field setup you can right click and select computer antenna parameters and it will give you the radiated power from the structure. That value should have all loss included in it.
Sam Belkin thank you for your reply.
Suppose I want to simulate a 2-port network only for matching circuit in ADS or any other circuit simulation tool. Suppose Port 1 is source, then port 2 should be the antenna input impedance. Antenna is operating from 2.4 to 2.48 GHz. In this case, what will be the port 2 impedance. Should I load the port 2 impedance with antenna input impedance of a single frequency?
Your bandwidth is narrow, only 0.08GHz. It means that you may use single-point narrowband matching. Knowing source and load impedance you can easily calculate possible matching circuits of different configurations and component values. I think that a simple 2nd order network must be good enough. If you know these numbers, I can calculate it for you. The alternative way is to use the Smith chart and do calculations there.
Hello,
There are two major factors, one is reflected power and other is absorbed power and third factor which is losses in design like due to metal, dielectric, coupling, external etc. So, according to friis equation, spatial loss is related to wavelength, distance covered, so this can be done manually or by calculating S11 directly from plot getting from CST as suggested by professors above.
Thanks
Rana Hamza Shakil, I think you explain some theoretical basis but did not provide a practical answer to the question asked. Reality is different.
Sam Belkin I have simulated the antenna matching components separately in Ansys circuit that I used to match the antenna in HFSS. Port 1 is the source (50 ohm) and port 2 is the input impedance of the antenna @2.45 GHz. From the simulated S21, I am getting the matching circuit loss about 0.5 dB which seems reasonable to me. Is there anything do I need to change.? I have attached the circuit schematic and S parameter response here.
Manjurul Ahsan Riheen, If you used the real impedance parameters for the antenna, i.e. S-parameter file, it is good enough and you have the answer to the matching circuit insertion loss value. This is exactly the method that I advised. Unfortunately, I cannot check it because I have no S-parameter file for your antenna. However, if you are well familiar with such kinds of simulations and your simulation tool, you can trust this result.
Sam Belkin yes, I used the Antenna real impedance parameter for the port 2.
Thank you for the suggestions. Appreciate your help.
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