I designed one microstrip patch antenna on FR-4 substrate in HFSS software. It is giving radiation efficiency of 45 % and return loss of -12 dB at 3 GHz. This low radiation efficiency may be due to high copper and dielectric losses because total output power = Input power given - copper loss - dielectric loss - radiation loss - impedance mismatch loss. So, I want to calculate both copper loss and dielectric loss of this patch antenna in hFSS software.
Also, Is there any relationship between return loss and copper, dielectric losses ?
Can anyone help me ?
Thanks in advance,
Sreenath
Calculating different losses are quite simple. In HFSS, you have to use field calculator to find unusual parameter. Different types are losses can easily be calculated using field calculator. After simulation, find surface integration of |n X H|^2 using field calculator. Other losses can also be evaluated using similar process
Before using HFSS, if you want to learn the procedure, please consult, Advanced EM theory book by C A Balanis (rectangular waveguide section). After solving this, it would be better to use HFSS for your problem.
Copper and dielectric losses can improve S11. A microstrip calculator (Rogers) indicates FR4 might have 3 dB/m of attenuation and a Q of about 150 at 3 GHz, so you might be losing half the power in the patch if the bandwidth is 40 MHz (Q of 75). Unless the feedline is 1 m long you shouldn't be losing much in that. If the feed is 10 cm long then it will improve S11 by 0.6 dB because of losses in it, and reduce the efficiency by 0.3 dB.
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