Terminator3
Advanced Member level 3
In case of air filled waveguide or SIW with Er<2.5 performance of SIW slot array is good, and it is easy to predict by using simple calculations. But when Er=4, slot array is performing poor. Single radiating slot in SIW cavity still could be optimized and perform great. Although, when slots are combined in series, current disturbed very oddly and unpredictable along SIW array. Even with very thin slots with small displacement from SIW center axis. Scaling design to lower dielectric constant eliminates such problems, and best results are obtained with air filled waveguide (good with Er around 2). I suspect it is because of power is not radiated properly when high dielectric constant slot meets air?