Surface losses in Microstrip antenna
I'm designing an Microstrip antenna. Please give your suggestion to reduce the surface losses.
Can I use any foam like Rohacell?
Hello Barani,
I assume you mean dielectric loss?
Try to understand why the microstrip (patch?) antenna works as it does, then you will learn that increasing the dielectric thickness reduces loss (w.r.t. for example FR4) and increases bandwidth. Having more air under it (foam), does reduce dielectric loss significantly as the total amount of absorbing material reduces.
I had one experience with a foam planar antenna (Low UHF range, small volume antenna with Q > 200). Though the datasheet said "moisture resistant" (or similar text), it did absorb some moisture over time reducing the antenna efficiency with about 30%.
Foam can be a good alternative for solid dielectrics in planar antennas with groundplane, but the material is less robust (less dimensional stability, more influence from temperature, moisture, less stiffness, etc). Depending on available budget, environmental issues, and stability requirments other (construction) foam may be an alternative too.
Regarding your question, this can only be answered with 99.99% conficence, when taking all details into account.