Low-Profile Dual-Polarized Omnidirectional Antenna for Broadband Indoor Distributed Antenna System

Abstract

Abstract-A low-profile dual-polarized omnidirectional antenna with an overall height of 80 mm is presented in this paper for broadband indoor distributed antenna system (IDAS). The proposed antenna consists of an improved discone antenna for vertical polarization (VP) and a printed dipole array with five pairs of dipoles for horizontal polarization (HP). The VP element is a combination of three radiation patches, a cone-shaped feeding structure, a circular shorted loading patch and a coupling ring. By loading the shorted patch and coupling ring over the top and at the bottom of the radiation patches, the bandwidth for VP is significantly enlarged while the antenna height is reduced. Simulated and measured results indicate that the operating bands of 0.86-5.62 GHz for VP and 1.62-2.71 for HP are realized. Omnidirectional radiation patterns in horizontal plane for HP and VP, good port isolation of greater than 26 dB, low cross-polarization level, and stable gain (2.6-5.6 dBi for VP and 2.8-4.2 dBi for HP) are achieved during the operating bands, which demonstrate the proposed antenna can be widely used for broadband IDAS.

A Low-Profile Wideband Monocone Antenna Using Bent Shorting Strips

“…For reference 1, a -10 dB impedance bandwidth of 1680 MHz (1820-3500 MHz) is obtained. To expand the low frequency limit, the shorting strips are employed such that an additional resonance mode is generated below the fundamental mode [13,21]. We adopted the bent shorting strip instead of a straight shorting strip to improve the impedance matching at around 1.2 GHz, as well as to minimize the antenna height.…”

“…The use of ferrite in the monocone antenna mounting expands the low-frequency band, but its use is costly and limited to the high-frequency band. The impedance bandwidth of monocone antennas has been improved by various methods, such as adding a shorting-pin [5][6][7][8][9][10][11][12], employing dual-sleeve structures on the ground plane [13][14][15], loading a dielectric substrate in the feed region [16], loading high-permittivity materials around the antenna [17], adding a top-cross plate [18], and cutting slots on the top-loaded patch [19]. However, the profiles of these monocone antennas are peaked relatively sharply, resulting in impedance bandwidths that are not sufficiently wide.…”

“…To expand the low frequency limit, the shorting strips are employed such that an additional 82 resonance mode is generated below the fundamental mode [13,21]. We adopted the bent shorting…”

Design and Analysis of a Broadband High Isolation Dual-Polarized Omnidirectional Antenna

“…Even though the 5G communication technology is coming and has become one of the hot research issues, because of the large amount of coverage, 4G antennas will still play a key role in the communication service in the further years. Moreover, owing to the merits of 360 • full coverage radiation in the horizontal plane and supporting a free alignment between receiving and transmitting antennas, omnidirectional antennas have been widely used in base stations [2][3][4][5]. On the other hand, due to the properties of enhancing the channel capacity and mitigating multipath fading, dual-polarized antennas possessing two orthogonal electrical field components in the direction of radiation are also extensively applied in many modern communication systems [6].…”

Enhanced Bandwidth of a Horizontally Polarized Omnidirectional Printed Antenna Array Based on Dual-Dipole Structure

“…The antenna in [11] with a modified annular ring slot and modified printed arc dipole array has a low profile, but the bandwidth is only 11.1%. In [12][13][14][15], dipoles are introduced to produce HP omnidirectional radiation patterns. Nevertheless, they cannot be mounted in constrained space due to the relatively high profiles.…”