Monopole Type Radiation Pattern Research Articles

Design of a CPW fed compact bow‐tie microstrip antenna with versatile frequency tunability

A compact coplanar waveguide (CPW) fed frequency reconfigurable bow-tie microstrip antenna is proposed and experimentally verified which can be tuned at different bands between 1.94 and 3.27 GHz in single-band and dual-band modes. Two slots are carefully introduced on the ground plane of the antenna where two active varactor diodes are placed to vary its fundamental mode of radiation by variation of capacitance. To validate the antenna design, a fully functional prototype is fabricated and measured which ensures that the device can be operated at different frequencies of 2.02, 2.19 and 2.37 GHz with 35.9, 30.8 and 24.6% of impedance bandwidth, respectively, in the single-band mode. In dual-band reconfigurability mode, the resonant frequency of the antenna can be varied at 2.08, 2.17 and 2.3 GHz with a higher mode band within 2.7 and 3.3 GHz. The antenna shows maximum gain of 1.33 dB with 96.9% efficiency and 1.5 dB with 95.4% efficiency for single-band and dual-band reconfigurability mode, respectively. More importantly, the antenna has a compact dimension (0.31λ×0.32λ×0.0103λ at 1.94 GHz) and it produces symmetrical monopole type radiation pattern at all tunable bands.

A Novel Four Element Low Profile and Compact Conical Dielectric Resonator Antenna for Wideband Applications

In this paper, a four element Conical Dielectric Resonator Antenna fed through coaxial probe is presented. This Low Profile and compact novel Antenna is designed for Wideband application and its input and radiation characteristics determined through the Ansoft High Frequency Structure Simulator (HFSS) Software. The proposed antenna provides wide Bandwidth (45%) and high average gain (5.15 dBi) with Monopole type Radiation Pattern.

Two Element Half Split Cylindrical Dielectric Resonator Antenna for Wireless Applications

A two element half split Cylindrical Dielectric Resonator Antenna (CDRA) with probe feed is proposed for wideband monopole-type radiation pattern. The proposed antenna has been designed and fabricated. The input and radiation characteristics of the proposed antenna have been determined through the Ansoft HFSS simulation software. Simulation results are compared with measured results and found good agreement. The input characteristics of the proposed antenna have been also compared with half split CDRA. The proposed antenna provides wide bandwidth (≈66%) and monopole type radiation pattern with low cross polarization level for wireless application.

Four element triangular dielectric resonator antenna for wireless application

A wideband four element triangular dielectric resonator antenna (TDRA) has been designed and fabricated by using 50 Ω coaxial probe feed. The input and radiation characteristics of the proposed antenna have been extracted through Ansoft HFSS and CST Microwave Studio simulation software and compared with the experimental results. The simulated results have been in good agreement with the experimental results. The proposed antenna characteristics have also been compared with the same dimensions of the single element TDRA, and found enhancement in bandwidth with lower resonant frequency. Its performance has also been compared with same area (equal to proposed antenna) of single element TDRA. The proposed antenna provides nearly 37% bandwidth (|S11| < −10 dB) at a resonant frequency of 5.45 GHz with 4.76 dBi peak gain. The symmetry and uniformity in the radiation patterns is obtained consistently for the entire operating bandwidth. The proposed antenna shows consistently symmetric monopole type radiation pattern with low cross polarization for WLAN (IEEE 802.16) and WiMAX applications. The performance of the proposed antenna has been compared with some similar type of dielectric resonator antenna (DRA) shapes and it has been observed that TDRA is taking very less radiation area for giving better performance than other DRA shapes.

Two-Port Pattern Diversity Antenna for 3G and 4G MIMO Indoor Applications

A two-port pattern diversity antenna is presented. The antenna is a combination of a low-profile monocone antenna and a broadband microstrip antenna. The low-profile monocone antenna is loaded with a cup-shaped patch and shorted with four metallic wires to the ground. The broadband microstrip antenna is fed by a probe-ring-slot coupling structure. The two antennas are integrated by sharing parts of the antenna radiators, resulting in a compact structure. The difficulties of placing coaxial cables are simply solved by reusing the shorting wires. A prototype of the proposed antenna is designed, fabricated, and measured. Its overall height is 3.915 cm. The low-profile monocone antenna achieves an impedance bandwidth of 114% from 750 MHz to 2.73 GHz, covering the GSM-850/900, GSM1800/1900/UMTS, and LTE800/2300/2500 bands. The broadband microstrip antenna provides an impedance bandwidth of 44% from 1.89 to 2.9 GHz, covering UMTS/LTE2300/2500 bands. The isolation between the two antennas is greater than 15 dB in the whole bands. The low-profile monocone antenna has a monopole-type radiation pattern, and the broadband microstrip antenna has a microstrip-antenna-type radiation pattern, which indicates that the proposed antenna can provide pattern diversity characteristics. The proposed antenna is suitable for 3G and 4G indoor applications and is also compatible with 2G (GSM) applications.

Stacked Conical Ring Dielectric Resonator Antenna Excited by a Monopole for Improved Ultrawide Bandwidth

Stacked conical ring dielectric resonator antennas (DRA) excited by an axi-symmetric coaxial monopole are investigated numerically and experimentally for improved bandwidth. The bandwidth improvement is due to an extra resonance which occurs near the frequency where the monopole height is about a full wavelength. We consider two cases of the hybrid antenna: one case in which the tips of both cones face up and a second case in which the top cone is inverted to form a “sand-glass” shaped DRA. Measured data were obtained to validate the results of simulations. The proposed hybrid antennas can easily offer a fractional impedance bandwidth up to 138% along with monopole type radiation pattern. The antennas have a relatively low peak gain around the extra resonance.

Dual-Frequency and Broadband Circular Patch Antennas With a Monopole-Type Pattern Based on Epsilon-Negative Transmission Line

Dual-frequency and broadband circular patch antennas based on epsilon-negative (ENG) transmission line (TL) with omnidirectional patterns are presented. The ENG TL is achieved by placing mushroom structures along its circumference. Compared to the conventional circular patch antenna whose fundamental operation mode is TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode, the fundamental operation mode of the new antenna is TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode with a monopole-type radiation pattern. With careful design, two omnidirectional modes, TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> , can be excited simultaneously. Through this excitation, a dual-frequency antenna with monopole-type pattern can be realized. Frequency ratio can be tuned by changing the number of mushroom unit cells. A broadband antenna can then be implemented by optimizing the frequency ratio. The performances of the proposed antennas are studied numerically and experimentally. The measured and simulated results are in good agreement.

Low-profile folded-monopole antenna with unbalanced composite right-∕left-handed transmission line

A low-profile folded-monopole antenna with high radiation efficiency is presented, consisting of only two unbalanced composite right-/left-handed transmission line unit cells. An even-odd mode analysis shows that the even mode necessary to realise the folded-monopole effect prevails at the zeroth-order frequency, determined by the shunt resonance of the unbalanced unit cell. Loading a spiral inductor in each unit cell's top patch can keep the antenna in a low profile at a relatively low self-resonant frequency, and a substantial increase in the radiation resistance is generated according to the multiple folded monopole theory, enabling the antenna to be well matched to 50 Ω without adopting any external matching network. A prototype antenna of λ/10 × λ/20 × λ/10, operative at 3.0 GHz, has been fabricated and measured, which can achieve radiation efficiency of above 90% and fully omnidirectional monopole-type radiation pattern.

Button antenna on textiles for wireless local area network on body applications

A design of a wearable antenna for wireless local area network (WLAN) applications is presented in this study. The antenna consists of a button shape outer cylindrical structure and an internal central via connected to a top disc at one end and the metal ground plane at the other. The overall size and shape achieved are those of a standard metal jeans button which camouflages the antenna for wearable applications. The rigidness of the structure is greater than for previous wearable button antenna developments. The proposed wearable antenna is designed for 2.4 and 5 GHz with monopole-type radiation patterns at each band. This allows for transmission to other worn devices on the body. An investigation into the measured permittivity of cotton denim is presented and a section on the equivalent circuit modelling of the antenna and the fabric is given.

Low-Profile Folded Monopoles With Embedded Planar Metamaterial Phase-Shifting Lines

This paper presents the analysis, design and measurement of novel, low-profile, small-footprint folded monopoles employing planar metamaterial phase-shifting lines. These lines are composed of fully-printed spiral elements, that are inductively coupled and hence exhibit an effective high- mu property. An equivalent circuit for the proposed structure is presented, validating the operating principles of the antenna and the metamaterial line. The impact of the antenna profile and the ground plane size on the antenna performance is investigated using accurate full-wave simulations. A lambda/9 antenna prototype, designed to operate at 2.36 GHz, is fabricated and tested on both electrically large and small ground planes, achieving on average 80% radiation efficiency, 5% (110 MHz) and 2.5% (55 MHz) -10 dB measured bandwidths, respectively, and fully omnidirectional, vertically polarized, monopole-type radiation patterns.

ON THE RADIATION PATTERN OF THE L-SHAPED WIRE ANTENNA

An objective of the present study is to make a physical insight into the radiation properties of an L-shaped wire antenna. More specifically, the study is focused on the effects of the antenna geometry over the characteristic radiation pattern of an L-shaped wire antenna. Regarding the basic equations for the radiated field, three main regions according to the length-height ratio of an L-shaped wire antenna have been determined. The said regions depict the geometrical boundaries where the L-shaped wire antenna loses its characteristic monopoletype radiation pattern. In this sense and relating to the aspect ratio of the L-shaped antenna, the said radiation properties can be easily varied in order to achieve a half isotropic radiation pattern or even, a patch-type radiation pattern. Thus, the method described herein demonstrates that simple modifications applied to the geometry of a basic structure, allow obtaining radiation properties associated to more complex structures.

New Half-Hemispherical Dielectric Resonator Antenna for Broadband Monopole-Type Radiation

A new half-hemispherical dielectric resonator antenna (h-HDRA) is proposed and a two-element h-HDRA configuration is employed to design a broadband monopole-type radiator. Two half sections of a hemispherical DRA are employed to enhance the impedance bandwidth by introducing an additional resonant mode. Since the new geometry of an h-HDRA is studied here for the first time, it is characterized using simulation and experimental studies. Two closely spaced resonant modes, which in a two-element h-HDRA generate monopole-type radiation are investigated. Results for both the single and two-element h-HDRAs are presented. As much as 35% impedance bandwidth (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> <-10dB) with more than 5 dBi peak gain, 99.08% efficiency and monopole-type radiation pattern has been demonstrated using a prototype occupying a compact volume measuring 0.48lambda <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> by 0.2lambda <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> approximately, lambda <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> being the wave length corresponding to the center of the impedance bandwidth

A novel surface-wave antenna design using a thin periodically loaded ground plane

This paper presents a novel surface-wave antenna that realizes a low-profile configuration using a thin patch-loaded grounded slab, which has an in-phase reflection coefficient for plane waves, but no band gap for surface waves. When a dipole antenna is horizontally positioned near this artificial ground plane, it works like a transducer that converts the energy from the feeding probe into surface waves in the ground plane. The propagation and diffraction of the surface waves generate a monopole-type radiation pattern. The attractive antenna height, which is less than 10% of a typical monopole antenna, is desirable for wireless-communication systems. The performance of the surface-wave antenna is demonstrated through both the FDTD simulations and the measured results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 240–245, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21136