Lourembam Lolit Kumar Singh

In this letter, two miniaturized, broadband, and wide-angularly-stable metamaterial (MM)-inspired Frequency-Selective Surfaces (FSSs) are implemented. A comparative study has been conducted on the miniaturization of the structures. Both unit cells of the FSSs are constructed by depositing spiral-shaped meandered lines with identical physical dimensions on FR4 substrates ( ϵ_r = 4.4 h = 1.6 mm, and tanδ = 0.02). The achieved compact dimensions of structures A and B, in terms of the free-space wavelength (λ₀) , are (0.04λ₀)² and (0.06λ₀)² at 1.8 GHz and 2.4 GHz, respectively. The TE (y-polarization) and TM (x-polarization) modes, along with the equivalent circuit model (ECM), are analyzed to confirm the polarization insensitivity under various incidence angles. The band-stop and band-pass performances for shielding the GSM 1.8 GHz and WiFi 2.4 GHz bands, and boosting the 2.16 GHz and 3.8 GHz frequency bands are achieved. Finally, measurement has been done for the validation of the work.

The designing of Artificial Magnetic Conductor (AMC) backed patch antenna (PA) operating in low frequency range is state of the research. The research community is doing rigorous efforts to attain efficient antenna operating at low frequency range. In this paper, an effort has been made to design a AMC backed antenna operating at low frequency which offers dual band at 760 MHz and 940 MHz with high polarization purity of 15 dB and 21 dB and gain of 3.6 dBi and 7.1 dBi respectively. The proposed structure is best suited for the underground communication-based applications.

Investigations on Input Impedance and Radiation Pattern of a UWB Antenna for Microwave Imaging OLAYIWOLA CHARLES ADESOBA1,*, and RICHARD OLALEKAN THE FOLLOWING ARE OBSERVATIONS * Concept of the work is good to improve gain by using FSS reflector...

In the present era, the key challenge for a low frequency planar antenna applied to a wireless underground sensor network (WUSN) and other underground wireless communication is to achieve positive gain with good efficiency. Besides that, a relatively wider bandwidth with more than one operating frequency is desirable for operational versatility. In the present work, a simple artificial magnetic conductor (AMC) integrated rectangular microstrip antenna (RMA) of size 0.28λ ₀ ×0.28λ ₀ ×0.07λ ₀ is employed. By meticulously exploiting a dual periodic AMC along with dielectric strips (AMC radiating patch and AMC ground plane) and proper utilization of an L- probe feed, two resonances at 572 MHz (low band) and 768 MHz (high band) can be yielded with a wide bandwidth of around 12%. Unlike the classical RMA design, a transverse electric mode (TE) excited RMA is proposed. The proposed antenna can also achieve good positive gains of 4.3 dBi (572 MHz) and 6.1 dBi (768 MHz) across both bands with an efficiency of 71% and 75%, respectively.