Short Monopole Research Articles

Six‐band internal antenna for small‐size mobile phone

AbstractA promising six‐band internal antenna suitable for small‐size mobile phone application is presented. The mobile phone considered in this study has a system ground plane of length 60 mm only, much less than that of the general mobile phones. For such small‐size mobile phones, it is not easy for the embedded antenna to achieve a wide operating band at 900 MHz for GSM850/900 operation. The proposed antenna solved the problem with a reasonable occupied volume. The antenna mainly comprises three radiating elements of two longer monopoles and a shorter monopole, which are configured to occupy a volume of 3.6 cm3 only. The two longer monopoles incorporating an external parallel chip inductor lead to the successful excitation of a wide operating band for the antenna's lower band to cover GSM850/900 operation. Moreover, the three monopoles together contribute to the excitation of a very wide upper band to cover GSM1800/1900/UMTS/WLAN operation. That is, the antenna can perform six‐band operation for WWAN and WLAN communications. The proposed antenna is studied in detail in this article. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2242–2247, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23659

CPW‐FED shorted monopole antenna for broadband application

AbstractBy embedding two folded narrow slots into a rectangular patch, a shorted monopole fed by a coplanar waveguide (CPW) structure is obtained and can achieve broadband impedance matching for wireless application. Prototype of the obtained design has been constructed and experimentally studied. The measured results explore wide operation with −10 dB impedance bandwidth of 3.21 GHz, ranging from 4.29 to 7.5 GHz, and show good agreement with the numerical predictions. Also, good radiation pattern and high antenna gains over the operating band have also been observed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 787–789, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23210

Internal shorted planar monopole antenna embedded with a resonant spiral slot for penta‐band mobile phone application

AbstractAn internal shorted planar monopole antenna embedded with a resonant spiral slot for GSM850/900/DCS/PCS/UMTS operation in the mobile phone is presented. The planar monopole is printed on an FR4 substrate of small size 10 × 45 mm2, and a spiral slot of length 108 mm is embedded therein. The planar monopole is then placed above and perpendicular to the top edge, with a small distance of 7 mm, of the system ground plane of the mobile phone to operate as an internal antenna. A coupled feed printed on the top no‐ground portion of the system circuit board is used to excite both the planar monopole and the spiral slot to generate two wide bands covering GSM850/900 and DCS/PCS/UMTS operation, respectively. The antenna is also suitable to integrate with the associated electronic components, such as the speaker, to achieve a compact integration of the antenna inside the mobile phone. Experimental and SPEAG SEMCAD‐X simulation results of the proposed antenna are presented. The user's hand effects on impedance and radiation characteristics of the antenna are also analyzed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 529–536, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23126

Enabling Antenna Systems for Extreme Deep-Space Mission Applications

Two NASA deep-space probes, Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) and New Horizons (NH), are moving towards the extremes of our solar system (Mercury and Pluto). The delivery of the science in these extreme environments is a challenge, and the missions require unique approaches. MESSENGER'S antenna system utilizes the first electronically scanned high-gain array for a deep-space telecommunication application. The array, which provides the high-data-rate downlink, is scanned in one dimension and is circularly polarized. Although a linearly polarized array would have satisfied the minimum mission science data rate requirements, MESSENGER'S circularly polarized array doubles it. To achieve this, the Johns Hopkins University/Applied Physics Laboratory (JHU/APL) developed an innovative technique to produce circular polarization from a narrow-wall slotted waveguide array. The new technique uses short parasitic monopoles mounted to the exterior of the waveguides. The result is a simple, lightweight, and all-metal circularly polarized array capable of operating at +300 OC, and a variety of measurement techniques were used to verify phased-array antenna system performance during qualification. The NH antenna system is a stack arrangement of a high-gain antenna (HGA), medium-gain antenna (MGA), and low-gain antenna (LGA). To minimize mission operating costs, the spacecraft is spin stabilized at times except during encounters to maintain a fixed spacecraft attitude. This approach and application for a narrow beamwidth antenna is unique for a deep-space mission, resulting in new approaches to accurately measure the gain and radio-frequency (RF) boresight direction in a compact range facility. Because of the importance of the HGA function to overall mission success, testing of the HGA system at operational temperatures of -200 OC was also performed. Recent in-flight measurement of the NH HGA pattern verified ground alignments. The RF design of the NH antenna also forms the baseline RF design for a deployable antenna system JHU/APL is developing called the Hybrid Deployable Antenna (HDA). The HDA combines a fixed parabolic dish with a deployable/inflatable reflector annulus that greatly increases antenna area after launch. This concept provides a high-payoff deployable antenna system that is being developed to address the all or nothing risk by providing a viable backup capability. This paper discusses some of the challenges to advance this concept for a future deep-space mission.

Internal shorted monopole antenna for the watch‐type wireless communication device for Bluetooth operation

AbstractAn internal shorted monopole antenna suitable to be embedded within the watch‐type wireless communication device is presented. The antenna generally has a planar configuration and is mounted conformal along the side surfaces of the wireless device to operate as an internal or concealed antenna. The antenna also shows a low profile of 4 mm only, yet providing a wide bandwidth for Bluetooth operation in the 2.4 GHz band (2400–2484 MHz). In addition, the antenna is designed to be short‐circuited to an upper ground plane mounted above the main system ground plane of the wireless device. With the proposed arrangement, reduced coupling between the antenna and the nearby lossy medium can be achieved. Hence, when the wireless device with the proposed antenna is worn around the user's wrist or forearm, which functions as a lossy medium, the antenna's radiation efficiency can still reach about 50% over the operating band. Details of the proposed antenna and the promising watch‐type wireless communication device are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 942–946, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22322

Broadband planar shorted monopole antenna for DTV signal reception in a portable media player

AbstractA novel broadband planar shorted monopole antenna suitable for digital television (DTV) signal reception for portable media player (PMP) applications is presented. The proposed shorted monopole antenna uses an internal matching circuit consisting of a chip capacitor and two narrow strips, which leads to a wide operating bandwidth (2.5:1 VSWR) of 340 MHz (about 53% centered at about 638 MHz) for the antenna. This wide bandwidth makes it very suitable for DTV signal reception in the 470–806 MHz band. In addition, owing to its planar structure, the proposed antenna can be firmly attached onto the surface of the PMP casing, when not in operation. This property is attractive for keeping the aesthetic appearance of the PMP equipped with the proposed antenna. Details of the experimental and simulation results are presented and analyzed. The design approach of selecting a proper chip capacitor for the proposed antenna is also discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 558–561, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22189

On the Crossed Field Antenna Performance

Lately, short antennas and Crossed Field Antennas (CFA) have attracted broadcast and amateur community attention. The CFA antenna has been developed in the last decade of the 20th century, trying to obtain a compact transmitting antenna for low and medium frequency AM bands. The CFA is intended to be used in order to get a low profile antenna and a supposed performance similar or better compared to a quarter-wave monopole. The CFA has a short monopole and a metallic disk close to the monopole base, both mechanical structures being fed by means of two separated generators. Thus, the CFA has two ports and can be analyzed from the Network Theory point of view. In this paper, the CFA has been studied exhaustively using the Transmission Line Method (TLM) in order to obtain an equivalent network and the antenna performance. Due to the lack of theoretical data to explain the CFA antenna behavior, the TLM has been validated by means of Moment Method simulations and some available experimental data

Numerical simulation of axially symmetric ultrawideband radiators

A code based on the finite-differences time-domain method has been developed to simulate axially symmetric ultrawideband radiators. The results obtained with the use of this code are compared with the now available data. Approaches to the determitation of the edges of the radiation zones for a short electric monopole are discussed.

Metamaterial-based efficient electrically small antennas

A metamaterial paradigm for achieving an efficient, electrically small antenna is introduced. Spherical shells of homogenous, isotropic negative permittivity (ENG) material are designed to create electrically small resonant systems for several antennas: an infinitesimal electric dipole, a very short center-fed cylindrical electric dipole, and a very short coaxially-fed electric monopole over an infinite ground plane. Analytical and numerical models demonstrate that a properly designed ENG shell provides a distributed inductive element resonantly matched to these highly capacitive electrically small antennas, i.e., an ENG shell can be designed to produce an electrically small system with a zero input reactance and an input resistance that is matched to a specified source resistance leading to overall efficiencies approaching unity. Losses and dispersion characteristics of the ENG materials are also included in the analytical models. Finite element numerical models of the various antenna-ENG shell systems are developed and used to predict their input impedances. These electrically small antenna-ENG shell systems with idealized dispersionless ENG material properties are shown to be very efficient and to have fractional bandwidths above the values associated with the Chu limit for the quality factor without any degradation in the radiation patterns of the antennas. Introducing dispersion and losses into the analytical models, the resulting bandwidths are shown to be reduced significantly, but remain slightly above (below) the corresponding Chu-based value for an energy-based limiting (Drude) dispersion model of the permittivity of the ENG shell.

A Study on Propagation of Monopole Ultrasonic Pulse by Simulation and Experiment

The shock wave or intense impulsive acoustic wave generated by an explosion, whether in air or in water, can produce unexpected lesions on the human body. Short monopole or impulsive-like ultrasonic pulses have a fast rise and are similar to a shock wave generated by an explosion. Investigation of the propagation of the monopole ultrasonic pulse in a lossy medium would be basic research for clarifing where the problems lie. In this study, we investigate the sound field of the monopole ultrasonic pulse in degassed water and glycerine by simulation and experiment, as well as its mechanism and effect in a lossy medium. The results show that waveform changed from a monopole to a dipole owing to a diffraction loss as the pulse transmitted in the medium, the amplitude of a received pulse was decreased considerably in glycerine by the large absorption, and also the rise of the amplitude was more gradual owing to the reduction of high-frequency components. A short monopole ultrasonic pulse will approach a shock wave if the wave propagates as a plane wave because the pulse remains impulsive. As a monopole ultrasonic pulse radiated from a small source is transmitted, a negative pressure grows, and its action on a medium per unit time will weaken owing to the large absorption of the transmission medium.

A foam‐base surface‐mountable shorted monopole antenna for WLAN application

AbstractA surface‐mountable shorted monopole antenna, constructed by folding a branch‐line metal strip onto a foam base for 2.4/5.2/5.8‐GHz WLAN operation, is presented. The branch‐line metal strip is comprised of a longer arm, a shorter arm, and a matching arm. The longer and shorter arms generate, respectively, a lower resonant mode covering the 2.4‐GHz band (2400–2484 MHz) and an upper resonant mode covering the 5.2‐GHz (5150–5350 MHz) and 5.8‐GHz (5725–5875 MHz) bands, and good impedance matching for frequencies across the two resonant modes is easily achieved by adjusting the distance between the feeding point and the shorting point in the matching arm. Experimental results of a constructed prototype of the proposed antenna are presented. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 501–503, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11103

A wide-band shorted planar monopole with bevel

A new wide-band shorted planar monopole with a bevel is presented. The numerical simulations and measurements demonstrate that the impedance bandwidth of a wide-band planar square monopole is shown to increase dramatically by combining bevelling and a shorting technique. The radiation pattern stability is also discussed.

A wideband arrowhead planar monopole antenna for multi‐service mobile systems

AbstractA compact wideband arrowhead planar monopole antenna is obtained by trimming the lower edges of the triangular planar monopole. The shorted arrowhead monopole is very suitable for use in multi‐service wireless systems, yielding a measured bandwidth of 5:1 for VSWR < 2.1 while retaining good radiation characteristics. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 188–190, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10863

A low‐profile, bent and shorted planar monopole antenna with reduced backward radiation for mobile phones

AbstractBy bending a planar monopole into an inverted‐U shape and short‐circuiting one end to the ground, a novel low‐profile monopole antenna with reduced backward radiation is obtained. The proposed antenna is easily fed by using a capacitively coupled feed, and is suitable for applications in mobile phones for providing reduced radiation toward the user's head. A prototype of the proposed antenna for DCS operation (1710–1880 MHz) is constructed, and measured and simulated results are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 146–147, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10258

Broadband low‐profile wire‐patch antenna

AbstractThis paper describes a wire‐patch air‐filled antenna, made up of two metallic stacked plates and center fed by a coaxial probe. This radiating element, which uses the original resonance phenomenon due to the presence of wires between the ground plane, the first and the second metallic stacked patches, has a wide bandwidth. This antenna also works like a short monopole for frequencies located below the fundamental cavity resonance mode, and close to the GSM frequency band. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 323–325, 2002.

Miniature circular GSM wire-patch antenna on small ground plane

A miniature stacked wire-patch antenna, on small ground plane is described. Its dimensions are only 1.2 times the radiating element. This uses the original resonance phenomenon, owing to the presence of wires, to work like a short monopole for GSM frequencies located below the fundamental cavity resonance mode. Owing to its low profile, low cost, large bandwidth and dipolar radiation pattern, this antenna is very suitable for automobile or indoor ceiling applications needing a very small ground plane.

Short medium frequency AM antennas

Short antennas have again attracted broadcaster attention. These kinds of antennas have been used since the 1920s. At that time it was the logical antenna as a new application of this service after more than twenty years of telegraphic transmissions. Telegraphic transmissions were the most important radio communication service at that time, and because of the long range needed the lowest frequencies as possible were employed. For this reason very short antennas were used even if their size was enormous. Top loaded monopoles were very popular and this technique was employed for broadcast use before the vertical transmitting mast exhaustive study was carried on in the thirties. Nowadays a short antenna would be useful for low power applications and specially to be mounted on building tops. Of course this kind of antennas is not intended to replace the optimum monopoles or vertical dipole where maximum efficiency, maximum gain and antifading properties were achieved after exhaustive studies and after long experience theoretically and practically achieved. CFAs, short monopoles, short dipoles and short folded monopoles have been analyzed from the theoretical and practical point of view in order to choose the simplest and most efficient. model to fulfill downtown stringent requirements.

A Study on the Conditions for Generation of Monopole Ultrasonic Pulse by Piezoelectric Polymer Film Transducers

Short monopole ultrasonic pulses can be radiated from piezoelectric polymer film transducers driven by a step-function voltage with a fast rising time and low output impedance. In this study, we investigated the conditions for transmitting a monopole ultrasonic pulse by simulation and experiment. We clarify that the length of the pulse width is limited by transmission time (Th ) in the direction of the thickness of the film transducer. By the simulations and experiments with the received pulse by changing the acoustic impedance of the backing material, it was also found that the backing material should be matched when the rising time of the driving step-function voltage is shorter than Th . It is also shown that the source impedance of the driving circuit is an important factor in generating short ultrasonic pulses.

Combination dielectric resonator, power combiner, and antenna

A rectangular dielectric resonator housed in a cutoff parallel-plate waveguide is used both as a radiating element and microwave power combiner. The resonator is excited by using tuned electrically short monopole antennas to induce a longitudinal electric operating mode. The resonator is then used in conjunction with free-running oscillators in order to provide, via mutual injection locking, stable in-phase power combining. Furthermore, the resonator is arranged such that one of its faces radiates a portion of the power-combined signal. Since the resonator is housed in a cutoff waveguide, the cross-polarization radiation from the antenna is suppressed. It was found that, for a single element, a gain in the azimuthal plane of 5 dB could be achieved and, for a two-element array, a gain of 7 dB was obtained with better than -25-dB cross polarization for each case. The oscillator power-combining efficiency for a single-element antenna (two oscillators) was 91%, and the spatial power-combining efficiency for a two-element antenna array, (four oscillators) was found to be 90%. In addition, it is shown that the presence of the dielectric inserts in conjunction with coupled oscillator dynamics provides moderate overall oscillator phase noise improvement.

Experiments on Monopole Ultrasonic Pulse Radiated from Piezoelectric Polymer Film Transducers

We found experimentally that short monopole ultrasonic pulses can be radiated from a piezoelectric polymer film transducer driven by a step-function voltage with a fast rising time and low output impedance. We clarified that the pulse width of the received ultrasonic monopole pulse depends on the rising time of step-function driving voltage, and is limited by transmission time (Th) in the thickness direction of the film.