Abstract-A compact planar monopole UWB antenna with quadruple band-notched characteristics is analyzed and presented. By introducing a C-shaped slot, nested C-shaped slot in the radiating patch and U-shaped slot in the feed line, quadruple band-notched characteristics are achieved at frequencies of 2.5, 3.7, 5.8 and 8.2 GHz. The proposed antenna has been fabricated and tested. Measured impedance bandwidth of the antenna is 2.35-12 GHz, which covers Bluetooth and UWB band, for VSWR < 2 and also has four stop bands of 2.44-2.77, 3.42-3.97, 5.45-5.98 and 8-8.68 GHz, for VSWR > 2, for rejecting 2.5/3.5 GHz WiMAX, WLAN and ITU 8 GHz band signals, respectively. The average gain of this antenna is 4.30 dBi with a variation of ±1.8 dBi over the whole impedance bandwidth. Significant gain reduction over the rejected band is also observed. The antenna shows good omnidirectional radiation patterns in the passband with a compact size of 40 mm × 34 mm.
A multi‐polarised quad‐band planar circular disc monopole antenna consisting of a parasitic double T‐stub and parasitic long and short inverted L‐stubs is presented. By loading parasitic multistubs along the y‐axis behind a circular patch, the antenna can yield four resonance modes at 2.5, 4.5, 5.7, and 7.7 GHz frequencies while keeping the size of 30 × 40 mm2. The proposed antenna has been fabricated and experimentally studied. The measured impedance bandwidths of 290 MHz (2.36–2.65 GHz), 540 MHz (4.28–4.82 GHz), 530 MHz (5.47–6.0 GHz), and 780 MHz (7.28–8.06 GHz), for Bluetooth, 2.4/5.8 GHz wireless local area network, 2.5/5.5 GHz worldwide interoperability for microwave access, 5.9 GHz intelligent transportation systems (ITS), downlink of Indian National Satellite System and X‐band satellite applications. The 3 dB axial ratio bandwidth is 280 MHz (5.79–6.07 GHz) for the 5.9 GHz ITS band. The antenna E‐field radiation has y‐directed (vertical linear) polarisation at first, second, third resonance bands and slant + 45° linear polarisation at the fourth resonance band. At the ITS band, the E‐field radiation has right‐handed circular polarisation. In addition, the design procedure, electrical model and effects of parasitic stub dimensions on the antenna characteristics are discussed.
A compact coplanar waveguide (CPW)-fed ultrawideband printed circular monopole antenna with band-notch characteristics is presented in this paper. The proposed antenna consists of a split ring resonator (SRR) in the circular patch to achieve a band notched characteristics in the WLAN (5.15-5.825 GHz) band. The predicted VSWR, frequency notch behavior in VSWR, gain and radiation patterns are analyzed. The antenna has an operating impedance bandwidth from 2.77 GHz to 12 GHz, with a band-notched from 5.02 GHz to 5.88 GHz band. VSWR is less than 2 (S11 < -10 dB) over the operating frequency band except band-notch frequency range. The gain variation of this antenna over the ultra-wideband range is 2.55 dBi to 5.28 dBi. In the band-notched region, there is a significant fall in gain.
A miniaturized rectangular monopole antenna (RMA) integrated with a T-shaped stub, inverted long and short L-shaped stub resonators based on application of the theory of characteristic modes (CMs) is investigated for multiband operation. CMs of embedded multistubs resonators on the RMA are examined and perceived that the entire structure is able to excite magnetic and electric CMs, in which three valuable CMs at 2.69/3.68/5.35 GHz are attained to cover WiMAX and WLAN bands. Based on CM analysis, the design formulation of multistubs resonators loaded antenna is presented. The proposed multiband antenna has been fabricated, tested, and experimentally characterized. The measured fractional bandwidths (FBWs) are 7.03% (180 MHz, 2.47-2.65 GHz), 10.43% (360 MHz, 3.27-3.63 GHz), and 11.42% (630 MHz, 5.20-5.83 GHz). The antenna exhibits isolated multiple frequency bands, stable monopole-like radiation patterns, and flat realized gains over the operating resonance bands while maintaining the small antenna size.
A new design of compact elliptical microstrip patch antenna is proposed for Ku-band applications. The proposed antenna consists of elliptical patch on RO3003 substrate followed by a thin foam substrate as dielectric followed by an infinite ground plane. In the ground plane, a square slot below the elliptical patch is cut. Theoretical reflection coefficient, gain and radiation characteristics of the antenna are discussed in this paper. The simulation results show return loss (S 11 ) better than 22.98dB at resonant frequency 14.6 GHz with the impedance bandwidth 33.56% or 3.95 GHz (12.9 GHz to 16.85 GHz) for voltage standing wave ratio (VSWR) < 2 and 98.77% or 12.41 GHz (6.15 GHz to 18.15 GHz) for VSWR ≤ 2.3. The variation in gain is less than 1dB over the entire frequency range. The antenna presents nearly uniform radiation patterns across the frequency band with VSWR <2. The overall size of proposed antenna is 50mm x 50mm x 3.162mm.
A millimetre wave antenna array, mounted on a space vehicle re-entering the Earth's atmosphere, encounters a high density plasma around it. At high antenna power, the millimetre wave field heats the electrons nonuniformly. The electron temperature, Te, follows the antenna pattern, being maximum along the direction of the principal maximum (z-axis) and falling off rapidly across it. The ambipolar plasma diffusion under the pressure gradient force creates a refractive index profile with maximum on the z-axis, leading to self-convergence of the millimetre wave and enhancement in the effective gain of the antenna.
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