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A low-profile multi-port dual-band antenna with pattern and polarization diversity is presented for 2.45 and 5.8 GHz bands. The antenna consists of a monopolar patch for vertically polarized (VP) omnidirectional radiation and four combining printed-dipole and tapered-slot elements arranged in a circular shape for horizontally polarized (HP) multibeam radiation, and consequently, both pattern and polarization diversities are achieved in the full azimuth plane. The monopolar patch employs four vias and a square-ring slot to excite T M 01 and T M 02 modes at 2.45 and 5.8 GHz, respectively. Each HP element utilizes printed-dipole and tapered-slot modes for the lower and upper bands, respectively. The VP and HP elements are collocated with a common ground plane, which not only allows a low profile but also broadens the lower band of the monopolar mode. The final design with 0.03 λ 2.45 - G H z height yields a measured 10-dB return loss bandwidth of 8.6% and 6.7% at 2.45 and 5.8 GHz, respectively, and an isolation ≥ 20 dB among all the ports. Its pattern and polarization diversities are validated by far-field measurements. [ABSTRACT FROM AUTHOR]

In this paper, a low-profile tripolarized antenna with the wideband operation is presented. It includes a monopolar patch element for vertically linear polarization (LP) omnidirectional radiation in the horizontal plane and two orthogonal dipoles for x- and y-direction LP broadside radiations. In order to achieve the wideband, nevertheless keeping the low-profile, the monopolar patch antenna is coupled with an annular ring, while the two orthogonal dipoles are incorporated with a metasurface. Optimized design with a profile of 0.09λmin (λmin is the free space wavelength referring to the lowest operational frequency) has been fabricated and measured. The measurements result in an overlapped bandwidth of 24.45% (2.19-2.80 GHz) for reflection coefficient

This paper presents a broadband dual‐polarized omnidirectional antenna with a simple feeding structure. It consists of a monopolar patch element for vertically linear polarization (VP) and a circular printed‐dipole array for horizontally linear polarization (HP). The monopolar patch antenna is loaded with shorting vias and coupled ring in order to broaden the VP bandwidth, nevertheless keeping a low profile. The printed dipoles with integrated balun are arranged on a circular substrate and incorporated with a 1‐to‐4 power divider for achieving the broadband HP omnidirectional radiation. One of the key features is to replace a shorting‐via in the monopolar patch by the coaxial line of the HP element, allowing a simple configuration and not affecting the VP radiation. The final design with a profile of 0.28λmin has been fabricated and measured. The measurements result in an overlapped impedance bandwidth of 25.4% (2.2‐2.84 GHz) and port‐to‐port isolation of >33 dB. Also, the antenna achieves the peak gain values of 8.0 and 5.6 dBi for the VP and HP radiations, respectively. [ABSTRACT FROM AUTHOR]

As a combination of three orthogonal dipoles, the tripolarized antenna has been demonstrated to significantly improve signal quality in scattering environment. In this communication, we propose a low-profile tripolarized antenna with wideband characteristics. The tristate includes 0° and 90° linear polarizations (LP) with the main beam at broadside and a vertically LP with omnidirectional pattern in the azimuth plane. The design consists of a monopolar patch and two orthogonal dipoles. The wideband performance for the monopolar patch is obtained from two nearly overlapped radiating modes controlled by an array of shorting wires. For the two orthogonal dipoles, the antenna profile is reduced with the effect of parasitic patches. One of the key design features is to utilize the shorting wire in the monopolar patch to feed the dipoles, allowing a simple design and avoiding any feeding network. The concept is experimentally verified with a prototype exhibiting an overlapped bandwidth of 14% with a low profile of $0.09\lambda $ , where $\lambda $ is the free-space wavelength at the lowest operating frequency. The measured peak gain in two broadside modes and in monopolar mode are 10 and 7.5 dBi, respectively. Measured isolation between any port is better than 31 dB in the whole frequency range. [ABSTRACT FROM AUTHOR]

The functionality of a dual-band frequency-reconfigurable antenna based on a microstrip patch is extended toward independent tuning of its two operational bands. The antenna has distinct monopolar and broadside radiation patterns at its lower and upper bands, respectively, and a previous realization only allowed simultaneous tuning of the two bands. In this paper, a more sophisticated bias scheme with two DC bias voltages and four varactors is introduced to extend the principle toward independent control of the resonance frequencies of the two bands. An antenna prototype has been designed, fabricated, and validated with experiments. The results demonstrate that the antenna achieves independent relative tuning ranges of about 11% at both frequency bands. [ABSTRACT FROM AUTHOR]

A novel dual-frequency broadband design of a stacked microstrip monopolar patch antenna is proposed for WLAN applications. The antenna is composed of a via-loaded ring on the bottom layer and a circular patch on the top layer, both of which are coupled-fed by a circular coupler. A broad lower band is generated by converging the TM01 and TM02 modes of the via-loaded ring, and a broad upper band is yielded by coupling the TM03 mode of the via-loaded ring and the TM02 mode of the circular patch. Measured results show that the proposed antenna provides a broad lower band from 2.28 to 2.55 GHz and a broad upper band from 5.15 to 5.9 GHz with a low profile of 6 mm. Monopole-like radiation patterns are obtained in the dual bands with peak gains in the lower and upper bands of about 5 and 6 dBi, respectively. [ABSTRACT FROM PUBLISHER]

A novel dual-band microstrip monopolar patch antenna with zeroth-order resonance is proposed and analyzed in this letter. The antenna is a combination of circular patch antenna with center-fed and circularly periodic mushroom units. With the zeroth-order resonant (ZOR) mode and TM02 mode, the proposed antenna can create horizontal magnetic loop currents on the patch, which lead to a low profile of 0.02λ at the low frequency band. The radiation mechanism of the proposed antenna is discussed. The antenna is fabricated on a double-layered printed circuit board (PCB) and center-fed by a 50- Ω SMA connector. Simulated and measured results show that the proposed antenna produces a stable monopole-like radiation pattern in two working frequency bands. The corresponding impedance bandwidths and gains are 0.75% and 5.1 dBi for the low frequency band and 20% and a range of 5.8-8 dBi for the high frequency band. [ABSTRACT FROM PUBLISHER]

ABSTRACT A single-layer substrate integrated waveguide (SIW) monopolar ring-slot antenna is proposed in this letter. It is based on a combination of a circular ring-slot etched in the SIW top wall and a set of shorting vias placed concentrically between the area bounded by the ring and the SIW bottom wall. Thanks to this configuration, a monopole-like radiation pattern is obtained. The antenna is designed for the 5.8 ISM frequency band, parametrically studied and experimentally verified in free space and in the vicinity of a muscle-equivalent phantom. Experimental results prove that the antenna is very well matched in the 5.8 GHz ISM band, has good radiation performance and small sensitivity to the surrounding environment. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1865-1869, 2014 [ABSTRACT FROM AUTHOR]

A new microstrip monopolar patch antenna is proposed and analyzed. The antenna has a wide bandwidth and a monopole like radiation pattern. Such antenna is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias. The antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the antenna, but also provides a guideline to design a broadband monopolar patch antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi. [ABSTRACT FROM PUBLISHER]