BITS Faculty Publications

Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867

Browse

Filters

2022 - 20245

Settings

Author: search.filters.author.Singhal, RahulSubject: search.filters.subject.Frequency selective surfaces (FSSs)

Search Results

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Performance Analysis of Traditional Band Pass/Band Stop Frequency Selective Surfaces for Distinct Frequency Domains of Electromagnetic Spectrum
    (IEEE, 2022) Singhal, Rahul
    Conventional square loop (SL) and complementary square loop (CSL) based frequency selective surfaces (FSSs) for distinct frequency range are designed, analyzed and compared in this paper. The SL and CSL type FSSs are designed to demonstrate band stop and band pass characteristics for S-band, Ku-Band, Ka-Band, G-band, Terahertz (THz) and Infrared (IR) frequency range respectively. The influence of dielectric substrate and metallic layer on FSS transmission characteristics are also studied for a purpose to identify the appropriate dielectric substrate and metallic layer to design the FSSs to obtain desired operating frequency, bandwidth of stop band and pass band and signal isolation/transmission. It is found that the signal transmission characteristics of FSSs at THz and IR frequencies deteriorates. Also, low lossy substrate materials are desired to improve the signal transmission and isolation levels at THz and IR frequency domains.
  • No Thumbnail Available
    Item
    Planar X-band reflecting surfaces based on rhombic loop pair
    (IEEE, 2022) Singhal, Rahul
    This paper presents design and analysis of two band stop FSSs offering wider band rejection along with polarization independence and linear reflection phase characteristics separately. The polarization dependent vertical dual rhombic loop (VDRL) unit cells arranged with periodicity ratio 1:2 as well as horizontal dual rhombic loop (HDRL) with periodicity ratio 2:1 exhibit two separate stop bands for TE and TM incident EM waves. Both FSSs are evolved from orthogonally oriented polarization dependent arrays of rhombic loop pairs those are first printed on both sides of dielectric substrate back-to-back (BTB) to form a BTBDRL FSS and later merged together on same side of dielectric substrate to form merged dual rhombic loop (MDRL) FSS respectively. The transmission responses of both VDRL and HDRL FSSs for orthogonally polarized incident EM waves coincide when they are cascaded back-to-back on both sides of dielectric material. The non-linearities in their reflection phase responses are compensated by merging both the arrays on the same side of dielectric substrate. The array of BTBDRL exhibits 4.15 GHz wide stop band with two transmission nulls at 7.46 GHz and 9.52 GHz respectively while the MDRL FSS provides 4.8 GHz wide stop band centered at 8.2 GHz.
  • No Thumbnail Available
    Item
    Performance analysis of frequency selective reflectors based on rectangular loop pair for wideband applications
    (Elsevier, 2023-07) Singhal, Rahul
    This paper presents performance analysis of single layered bandstop frequency selective surfaces (FSSs) for C-band and ultra-wideband (UWB) frequency ranges respectively. These FSSs are based on polarization dependent (PD) single rectangular loop pair (RLP). RLP arrays in square and rectangular grids are developed and simulated to evaluate signal rejection and reflection for incident transverse electric (TE) and transverse magnetic (TM) waves. Further, orthogonal patterns are printed back-to-back (BTB) on dielectric substrate to study wave propagation and effect on wave polarization. Non-linearities in the reflection phase of BTB arrays are then mitigated by printing orthogonal FSS arrays on the same side of the dielectric substrate. The equivalent circuit models (ECMs) of these FSSs are also presented to predict their transmission characteristics. Later, two FSSs with wideband and ultra-wideband rejection capability are developed and experiments are carried out. The array of merged RLP arranged in square grid exhibits stopband from 4.5 GHz to 8.4 GHz with polarization independence (PI) and it is angularly stable while merged array of RLP arranged in rectangular grid exhibit ultra-wide stopband from 2.3 GHz to 11.5 GHz but it is not angularly stable. The measured transmission responses of all FSSs proposed here are close to simulated results.
  • No Thumbnail Available
    Item
    Gain Enhancement of Triangular Slot X-band Antenna Using Rhombic Loop Frequency Selective Surfaces
    (Springer, 2024-04) Singhal, Rahul
    The paper presents boresight gain enhancement of a microstrip fed X-band triangular slot antenna using rhombic loop (RL) based frequency selective surfaces (FSSs). Two single side printed orthogonal layers of arrays of dual rhombic loops (DRLs) kept in pairs are stacked together to form cascaded dual rhombic loop (CDRL) based reflective surface which exhibits wide stop bands within X-band but with reflection phase non-linearities. The non-linearities are suppressed when both layers are printed back to back (BTB) on both sides of same dielectric substrate while they are completely eliminated when both the layers are printed on same side of the dielectric substrate to form a merged dual rhombic loop (MDRL) based FSS. A triangular slot antenna operating at 8.2 GHz is designed and integrated with these FSSs for a purpose to investigate their impact on antenna performance. Through simulations, it is found that antenna when integrated with MDRL FSS demonstrates superior performance. Later, the slot antenna and MDRL FSS are developed and integrated to perform experiments. The integrated antenna exhibits an impedance bandwidth of 650 MHz and a maximum gain of 8.5 dB in antenna boresight including 4.5 dB enhancement due to frequency selective reflectors.
  • No Thumbnail Available
    Item
    Dual rhombic loop-based frequency selective surfaces for X-band applications
    (Wiley, 2022) Singhal, Rahul
    Dual rhombic loop (DRL) based low-cost X-band frequency selective surfaces (FSSs) with stopband characteristics are presented in this study. Orthogonally oriented arrays of rhombic loop pairs are printed back-to-back (BTB) on both sides of dielectric substrate to achieve wide stopband characteristics with stable response under oblique incidences. The nonlinearities in the reflection phase of BTB DRL printed FSSs are compensated by printing orthogonally oriented rhombic loop pairs on the same side of the substrate. Merging orthogonally oriented rhombic loop pairs results in a single-layer wide stopband FSS with linear reflection phase under normal incidence. Both polarization dependent merged DRL (MDRL) and independent BTB DRL FSSs are developed and experimentally validated. As per measurements, the BTB printed FSS array exhibits 4.3 GHz wide stopband with transmission nulls at 7.9 and 10 GHz while the single side printed FSS exhibits 3.7 GHz wide stopband with transmission null at 8.3 GHz