A Study Of The Adjustable Multiband And Broadband Polarization-independent Electromagnetic Absorber

As a new kind of absorber,the adjustable polarization-independent electromagnetic absorber with its unique absorption performance plays a significant role in the field of the stealth technique.This paper makes a detailed study of the design and the analysis methods of the adjustable polarization-independent electromagnetic absorber,which is based on the transmission line theory.What is more,combined with the resonator,a polarization-independent electromagnetic absorber with multiband has been designed.The equivalent circuit model of the semicircle pattern with polarization sensitivity has been investigated in detail,and the circuit component parameters of the pattern have been extracted.By changing the value of the circuit component parameters and comparing the result of simulation,the corresponding changes of the pattern are presented,which confirms the accuracy of the proposed equivalent circuit model.Based on the mentioned equivalent circuit model,the new models of the rotationally symmetric semicircle pattern,which has two resistance loading modes,is discussed.When the resistor is series loading with the next array's,the absorption frequency shifts with the change of the resistance,which makes the model kind of LC series resonance circuit,and there is a good adjustability of the proposed absorber.However,when the resistor is parallel loading with each array's,the absorption frequency barely shifts with the change of the resistance,which makes the model kind of LC parallel resonance circuit,and that is why the absorption frequency of the absorber with parallel connection of the resistor cannot be adjusted.Comparing the performances of the sheet pattern and the ring pattern of the bow-tie and the semicircle,the reason why their performances stay the same after a series of changes is that the changes do not break the balance of electric dipole.By using the design of split-ring resonator,not only most of the absorption performance(5 – 7 GHz)has been remained,but also the balance of electric dipole has been broken.What is more,a new resonance at around 3.5 GHz has been found,which broadens the absorption band of the absorber in general.An adjustable multiband and broadband polarization-independent electromagnetic absorber has been designed based on the split-ring resonator.The proposed absorber is constructed by periodic array of units,which contains four split semi-circle ring resonators with different rotation angles.Measurement results show the proposed absorber obtains the reflectivity less than-10 dB covering 2.1 – 2.5 GHz and 3.1 – 6.8 GHz by tuning the bias voltage on the PIN diodes.In brief,this paper makes a detailed study of the design and the analysis methods of the adjustable polarization-independent electromagnetic absorber,and designs an adjustable polarization-independent electromagnetic absorber,after developing the original structure,which has a good performance at the target band.