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Deshmukh A.A.,EXTC | Ray K.P.,SAMEER
IEEE Antennas and Propagation Magazine | Year: 2012

Dual-band and broadband rectangular microstrip antennas are realized by cutting U slots, V slots, or a pair of rectangular slots inside the patch. In these designs, depending upon where the slot is cut, the slot length is taken to be equal to either a quarter-wavelength or a half-wavelength in length. However, these simpler approximations of slot length as a function of frequency do not give a close match for different slot lengths and their positions inside the patch. In this paper, the surface currents and voltage distributions for a dual-band pair of rectangular slots, and for U-slot-cut rectangular microstrip antennas, are studied over a wide frequency range. It was observed that the slot does not introduce any mode, but reduces the higher-order orthogonal mode resonance frequency of the patch and, along with the fundamental mode, realizes the dual-band response. Furthermore, by studying the current and voltage distributions, a formulation for the slot's resonant length on a glass epoxy substrate was proposed. The frequencies calculated using the proposed formulations agreed well with the simulated values, with an error of less than 5%. These formulations were also validated on RT-duroid substrate. © 2011 IEEE. Source


Deshmukh A.A.,EXTC | Ray K.P.,SAMEER
IEEE Antennas and Propagation Magazine | Year: 2014

The fundamental and higher-order modes of a compact ring microstrip antenna are discussed. This provides insight into the functioning of this configuration. To increase its bandwidth and gain, various broadband proximity-fed configurations of a ring microstrip antenna in the 1000 MHz frequency band are proposed. A detailed explanation for the broadband behavior of all these configurations is presented. The proximity-fed square-ring antenna yielded a bandwidth of more than 250 MHz. A further increase in its bandwidth was realized by cutting a pair of rectangular slots on the edges of the ring patch. The pair of slots reduced the orthogonal TM02 mode's resonance frequency of the patch and, along with the fundamental TM10 mode, yielded a bandwidth of more than 350 MHz. Furthermore, the proximity-fed gap-coupled configurations of rectangular-slot-cut C-shaped patches, which were derived from the ring patch, are proposed. These yielded a bandwidth of more than 500 MHz (>43%). Both of these slot-cut compact configurations gave broadside radiation patterns with gains of more than 6 dBi over the bandwidth. To further increase the gain and bandwidth of the slot-cut ring antenna, a multi-resonator configuration with parasitic ring patches, gap-coupled along the two coordinate axes, is proposed. This configuration yielded a bandwidth of more than 400 MHz with a peak gain of 9 dBi. In this configuration, a further increase in the bandwidth was realized by cutting a pair of rectangular slots on the edges of the ring patches that were gap-coupled along one of the coordinate axes. This configuration gave a bandwidth of more than 500 MHz with a peak gain of 9 dBi. © 1990-2011 IEEE. Source


Deshmukh A.A.,EXTC | Ray K.P.,SAMEER IIT Campus
IEEE Antennas and Propagation Magazine | Year: 2011

The bandwidth of a microstrip antenna is increased by using a thicker and lower-dielectric-constant substrate, or by using multi-resonator gap-coupled and stacked configurations, or by cutting a resonant slot inside the patch. However, with all of these methods, the bandwidth of the antenna is limited by the probe's inductance for substrate thicknesses greater than 0.060 to 0.070. For substrate thicknesses larger than 0.070, the bandwidth of the antenna can be increased by using a proximity-feeding method. In this paper, by using a combination of the proximity feeding technique and a thicker substrate, various broadband configurations of gap-coupled rectangular microstrip antennas, E-shaped and half-E-shaped microstrip antennas, and gap-coupled half-E-shaped microstrip antennas are proposed. All of these configurations give bandwidths in excess of 350 MHz ( 35% ), with gains of more than 7 dBi, in the 800 to 1200 MHz frequency band, with a broadside radiation pattern. © 2006 IEEE. Source


Deshmukh A.A.,EXTC | Ray K.P.,RFMSD
IEEE Antennas and Propagation Magazine | Year: 2013

A broadband configuration of a shorted-plate folded L-slot-cut folded-feed rectangular microstrip antenna was reported, which gave a bandwidth of 2840 MHz (133%). The broader bandwidth was obtained due to the coupling between various modes, which were either a half-wave or a quarter-wave in length. However, a clear description of the modes of the shorted patch that resulted in the broadband response was not given. In this paper, an analysis studying the broadband response of the reported configuration is presented. By studying the voltage and current distributions on the shorted patch, a formulation for its resonance frequency is proposed. The frequencies calculated using the proposed equation closely agreed with the simulated results. Furthermore, the broadband response of the reported configuration was analyzed by studying its resonance-curve plots and surface-current distribution. It was observed that the folded patch and a wing-like extension on the folded-patch portion, the L-slot, and the folded feed modified the various fundamental and higher-order mode resonance frequencies (such as f1/4, 0, f1/4, 1, etc.), as well as the impedances at these frequencies, to yield the broadband response. Furthermore, by optimizing the folded feed length, an increased bandwidth of 3504 MHz (139.2%) was obtained. Over the bandwidth, this configuration showed a radiation pattern with higher cross-polarization levels and with a gain of more than 5 dBi. © 2013 IEEE. Source


Deshmukh A.A.,EXTC | Ray K.P.,SAMEER
IEEE Antennas and Propagation Magazine | Year: 2013

A new ψ -shaped microstrip antenna is reported, which increased the bandwidth of the E-shaped microstrip antenna by cutting an additional pair of slots on the other radiating edge of the E-shaped patch. The ψ -shaped patch yielded a bandwidth of nearly 60% at a center frequency of around 5500 MHz. It gave a maximum gain of more than 10 dBi, which reduced to less than 4 dBi towards the higher frequencies of the bandwidth. In this paper, the broadband responses of the E-shaped and the reported ψ -shaped patches are studied. In the E-shaped patch, the pair of rectangular slots did not introduce any mode, but modified the TM20 mode's resonance frequency of the patch and, along with the fundamental TM01 mode, resulted in the broadband response. Furthermore, when an additional pair of slots were cut to realize the ψ -shaped patch, they modified the higher-order TM21 mode's resonance frequency of the patch. Along with the modified TM20 and TM01 modes, this yielded a larger bandwidth. Since the TM 21 mode was present towards the higher frequencies of the bandwidth, the gain was reduced to less than 4 dBi. Furthermore, a proximity-fed design of a ψ -shaped microstrip antenna in the same frequency band was proposed. The proposed configuration gave a higher bandwidth compared to the reported ψ -shaped patch, with better gain characteristics over the bandwidth. A proximityfed design of the ψ -shaped patch in the 1000 MHz frequency band was also proposed. It gave a bandwidth of more than 50% with a broadside radiation pattern, and a gain of more than 8 dBi over the complete bandwidth. ©2013 IEEE. Source

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