Abstract-Analysis of U-slot loaded patch stacked with H-shaped parasitic elements is given in this paper. It is found that the antenna exhibits dual resonance and both the resonance frequency (upper and lower) depends directly on slot width and inversely on slot length. Both upper and lower resonance frequency increase with increasing the value of h 2 . Typically the bandwidth at lower and upper resonance is found 3.66% and 10.25% respectively. The radiated power at higher frequency (beamwidth 64 • ) is 0.73 dB as compared to lower resonance frequency (beamwidth 71 • ). The theoretical results are compared with the simulated data obtained from IE3D.

A broadband stacked U-slot microstrip patch antenna is presented using circuit theory concept. The antenna shows two resonance frequencies that are very closely spaced to give broadband characteristics. The frequency band of 186 MHz (36.4% impedance bandwidth) is achieved for the proposed antenna. The theoretical results are in good agreement with the simulated results.

Abstract-In the present paper, a dual frequency resonance antenna is achieved by introducing half U-shaped slot in semicircular disk. It is analysed by using circuit theory concept. The resonance frequency is found to be 1.50 GHz and 2.32 GHz, and the bandwidth of the proposed antenna for lower and upper resonance frequency is found to be 5.96% and 11.08% respectively. It is found that the resonance frequency depends inversely on the slot length and feed point, while it increases with increasing the slot width and coaxial probe feed radius. The frequency ratio is found to be 1.54. The theoretical results are compared with IE3D simulation as well as reported experimental results, and they are in good agreement.

Abstract-A theoretical analysis of a gap-coupled stacked annular ring microstrip antenna with superstrate is performed in order to obtain wider bandwidth operation. The effects of air gap, superstrate thickness and feeding point location on the antenna performance are analyzed in TM 11 mode using equivalent circuit concept. It is noted that the proposed antenna is very sensitive to the feeding point location in TM 11 mode while annular ring microstrip patch antenna is independent of feed point in that mode. The optimized proposed antenna shows an impedance bandwidth of 13.96% whereas the antenna without air-gap has 8.75% bandwidth and without superstrate it has bandwidth of 10.89%. The theoretical results are compared with simulated and experimental results.

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