Sarath Kumar Annavarapu

The challenges adhere to design planar antenna for versatile soil condition in wireless underground communication has grabbed the attention of potential researchers and is the present state-of-the-art research. Specifically, the change in underground soil properties (with time and place) demands the requirement of planar antennas (≤1000MHz) with varied operating frequencies. However, designing such antenna with good radiation profile is undeniably thought-provoking as they suffer from very poor gain (usually negative). In this communication, a completely new concept of heterogeneous AMC with quasi-AMC properties has been exploited to yield 4 frequency bands (≤1000MHz) with good measured gains of 3 dBi, 4.1 dBi, 7.8 dBi, 7.5 dBi at 703 MHz, 835 MHz, 937 MHz and 1008 MHz respectively. Despite having a smaller ground plane (0.4λ ₀ × 0.4λ ₀ ), the proposed antenna exhibits good gain and efficiencies in the range of 66% - 92%. The present investigation aims to design the simple and efficient antenna structure which is judiciously achieved through the thoughtful modulation of AMC ground plane impedance.

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.

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.

In the modern era of wireless internet of things designing a planar antenna at relatively low frequency (P-band) with positive gain and high efficiency is exacting task. In this letter a planar P band microstrip antenna (a simple rectangular patch of size 0.16λ₀×0.20λ₀×0.01λ₀, smaller than classical quarter-wave patch) for WUSN is proposed. The proposed structure yields high gain with the judicious use of four shorting vias which are collocated along the side edges of the patch with a composite substrate (dielectric-Artificial Magnetic Conductor (AMC)). The results shows that the designed antenna resonates at 413 MHz with gain and efficiency of 3.1 dBi and 75%, respectively with a 10-dB impedance bandwidth of 2% (408–416 MHz)