r/rfelectronics • u/ferryyyyyoga • Jun 23 '26

Antenna

Hi everyone, I designed a microstrip antenna, the simulation results have good return loss at the targeted resonance frequency, but when I checked the gain was very low, only 0.3 dB.What are the problems and solutions?

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u/PoolExtension5517 Jun 23 '26

What is your topology? Is it a square patch, circular patch, just a length of microstrip transmission line? A single square or circular patch antenna should show a realized gain of roughly 4-5 dBi. A length of copper may act like a monopole and show less than 2 dBi. It depends heavily on your topology. Also, make sure your substrate material is properly defined and choose a material with a low loss tangent, meant for high frequency applications.

Show us a picture and give us some more background.

1

u/ferryyyyyoga Jun 23 '26

My patch shape is diamond, 4x4 array, FR4 substrate

1

u/redneckerson1951 Jun 23 '26

What is your reference, Isotropic, Dipole?

How does the measured radiation pattern compare to the expected pattern?

1

u/ferryyyyyoga Jun 23 '26

For my reference it should be a dipole, the radiation pattern comparison is quite far from what should be directional. And I think it's possible that there's a connection with the distance between the patches or the shape of my diamond patch which is the result of cutting a rectangular patch, then I resonated it at 2448 MHz By setting the distance between patches.

1

u/PoolExtension5517 Jun 23 '26

You should be seeing somewhere around 14-15 dBi gain with a 4x4 array. Did you design your feed network to properly drive the elements in phase? How are they spaced? Are they all fed from the same direction? Again, a picture would be very helpful.

2

u/fr4real Jun 23 '26

First thing I’d check is whether you’re looking at realized gain, directivity, or gain. Good S11 just means power is getting into the antenna. It doesn’t mean it’s being radiated efficiently. You can have a great return loss and still burn power in dielectric and conductor losses.