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Showing papers on "Active antenna published in 2007"


Journal ArticleDOI
TL;DR: The paper develops a dynamic antenna scheduling strategy for downlink MIMO communications, where a subset of the receive antennas at certain users is selectively disabled, and shows that increasing the number of antennas at some users can degrade the SLNR performance at other users.
Abstract: The paper develops a dynamic antenna scheduling strategy for downlink MIMO communications, where a subset of the receive antennas at certain users is selectively disabled. The proposed method improves the signal-to-leakage-plus-noise (SLNR) ratio performance of the system and it relaxes the condition on the number of transmit-receive antennas in comparison to traditional zero-forcing and time-scheduling strategies. The largest value that the SLNR can achieve is shown to be equal to the maximum eigenvalue of a certain random matrix combination, and the probability distribution of this eigenvalue is characterized in terms of a Whittaker function. The result shows that increasing the number of antennas at some users can degrade the SLNR performance at other users. This fact is used to propose an antenna scheduling scheme that leads to improvement in terms of SINR outage probabilities

242 citations


Journal ArticleDOI
TL;DR: In this article, an ultra wideband planar monopole antenna with a tunable band-notched response is proposed, which is realized by loading an embedded resonant slot with a varactor.
Abstract: An ultra-wideband (UWB) planar monopole antenna with a tunable band-notched response is proposed. Tuning of the rejected frequency is realised by loading an embedded resonant slot with a varactor. Simulations and measurements are presented for the proposed antenna, both in frequency and time domain.

75 citations


Journal ArticleDOI
TL;DR: The eight-meter-wavelength transient array (ETA) as mentioned in this paper is a radio telescope consisting of 12 dual-polarized, 38 MHz-resonant dipole elements which are individually instrumented, digitized, and analyzed in an attempt to detect rare and as-yet undetected single dispersed pulses believed to be associated with certain types of astronomical explosions.
Abstract: The eight-meter-wavelength transient array (ETA) is a new radio telescope consisting of 12 dual-polarized, 38 MHz-resonant dipole elements which are individually instrumented, digitized, and analyzed in an attempt to detect rare and as-yet undetected single dispersed pulses believed to be associated with certain types of astronomical explosions. This paper presents the design and demonstrated performance of ETA's dipole antennas. An inverted V-shaped design combined with a simple and inexpensive active balun yields sensitivity which is limited only by the external noise generated by the ubiquitous Galactic synchrotron emission over a range greater than the 27-49 MHz design range. The results confirm findings from a recent theoretical analysis, and the techniques described here may have applications in other problems requiring in situ evaluation of large low-frequency antennas

61 citations


Journal ArticleDOI
TL;DR: In this article, a novel contactless, differential feeding technique suitable for integrated active antenna design is demonstrated, which utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna, allowing electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna.
Abstract: A novel contact-less, differential feeding technique suitable for integrated active antenna design is demonstrated. This technique utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna. This allows electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna. In a balanced integrated antenna amplifier configuration, the proposed non-contact feeding method removes the need for any balun or power combining network. Hence in theory, a compact RF front-end design with lower losses can be realized. This feeding method has been successfully applied to the design of simple passive microstrip patch antennas and active integrated antennas (AIA). Simulated and measured results are also included to validate the proposed feeding concept and antenna designs. The performance of the proposed differential feeding technique on a simple microstrip patch antenna has been systematically studied. The study suggests that the proposed proximity method is broadband in nature, allowing antennas operating at different resonant frequencies to be swapped without the need to change the feed dimensions and without degrading the matching performance

54 citations


Proceedings ArticleDOI
Rob Maaskant1, E.E.M. Woestenburg1
09 Jun 2007
TL;DR: It is demonstrated that the active instead of the passive antenna reflection coefficient is the key parameter in realizing low-noise receiver designs.
Abstract: In this paper it is demonstrated that the active instead of the passive antenna reflection coefficient is the key parameter in realizing low-noise receiver designs.

48 citations


Book
01 Jan 2007
TL;DR: There is a way to incorporate active components into an antenna and transform it into a new kind of radiating structure that can take advantage of the latest advances in analog circuit design.
Abstract: Most antenna engineers are likely to believe that antennas are one technology that is more or less impervious to the rapidly advancing semiconductor industry. However, as demonstrated in this lecture, there is a way to incorporate active components into an antenna and transform it into a new kind of radiating structure that can take advantage of the latest advances in analog circuit design. The approach for making this transformation is to make use of non-Foster circuit elements in the matching network of the antenna. By doing so, we are no longer constrained by the laws of physics that apply to passive antennas. However, we must now design and construct very touchy active circuits. This new antenna technology is now in its infancy. The contributions of this lecture are (1) to summarize the current state-of-the-art in this subject, and (2) to introduce some new theoretical and practical tools for helping us to continue the advancement of this technology.

42 citations


Journal ArticleDOI
Shinya Sugiura1, Hideo Iizuka1
TL;DR: A novel type of smart antenna, called a reactively steered ring antenna array (RSRAA), is proposed, which is optimized at 2.4 GHz and is mounted on an automobile, and directivity control is found to be implemented effectively.
Abstract: A novel type of smart antenna, called a reactively steered ring antenna array (RSRAA), is proposed. The antenna features a conformal configuration with three overlapping one-wavelength ring elements. Directivity can be controlled by changing the values of variable reactance circuits that are embedded in the antenna. The antenna can be mounted on the windshield of an automobile without interfering with the view of the driver. An equivalent model of six dipole elements is derived from the original antenna configuration to enable simple calculation of directivity when a set of reactance values is given. The validity of the proposed equivalent model is confirmed by comparing simulation results calculated by the equivalent model and by the method of moments. Another simulation shows that the conventional reactance domain multiple signal classification algorithm can be applied to the proposed antenna while keeping the estimated direction-of-arrival number equal to the number of reactance circuits. In addition, the characteristics of an RSRAA, which is optimized at 2.4 GHz and is mounted on an automobile, are measured in an anechoic chamber, and directivity control is found to be implemented effectively.

39 citations


Journal ArticleDOI
TL;DR: A low-cost scheme for implementing in-building distributed antenna systems using the photonic-active-integrated-antenna (PhAIA) concept, whereby photonic devices are integrated directly with planar antennas is described.
Abstract: This paper describes a low-cost scheme for implementing in-building distributed antenna systems using the photonic-active-integrated-antenna (PhAIA) concept, whereby photonic devices are integrated directly with planar antennas. Deembedded input impedance is measured for an 850-nm vertical-cavity surface-emitting laser and photodiode from 0-10 GHz, and the devices are matched directly to the nonradiating edge of a rectangular-microstrip-patch antenna. Link gain, 1-dB compression point, and spurious-free dynamic range are measured in the links. The fully bidirectional system, which is far from being completely optimized, is then tested over a 300-m laboratory-based multimode fiber link and a 220-m in-building dark-fiber link. Results are shown for throughput and signal-to-noise ratio, and this paper shows that such systems can achieve up to 10-m RF range, at reduced throughput, with no RF amplification.

37 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed the use of the dielectric resonator antenna (DRA) as an oscillator load, named as DRAO, for the first time.
Abstract: For the first time, the idea of using the dielectric resonator antenna (DRA) as an oscillator load, named as DRAO, is presented in this paper. Unlike the conventional dielectric resonator oscillator (DRO), where the DR was merely used as a resonator, the DR here serves as both the radiating and oscillating loads. In addition, a compact tri-function hollow DR that incorporates the packaging function to the above dual function is demonstrated. The design procedures of the dual- and tri-function DRAOs are discussed. For demonstration, the DRAOs are designed at 1.85 GHz, which is used in the popular personal communications system (PCS). The return losses, input impedances, antenna gains, signal spectrums, phase noise, and radiation patterns of the two DRAOs are presented. It is shown that the loaded QL factor of the DRA can be increased by internally embedding a compact metallic cavity to the DR. It is found that with a higher loaded QL factor, the phase noise of the antenna oscillator using the hollow DRA (tri-function DRAO) is better than that using a solid DRA (dual-function DRAO).

33 citations


Journal ArticleDOI
Korkut Yegin1
TL;DR: In this paper, a multiple-element antenna is designed, built, and measured to satisfy all the requirements for emergency call applications, including passive antenna-to-antenna isolation and preamplifier filtering without affecting the noise figure.
Abstract: Many vehicular emergency call applications utilize a dual-band cellular phone for data exchange and Global Positioning System (GPS) antenna for localization. When the cellular phone antenna is transmitting in close proximity to the GPS antenna, the GPS low-noise amplifier (LNA) is expected to be not affected, i.e., remain linear during the operation. Most commercial GPS LNAs hardly meet this requirement, hence passive antenna-to-antenna isolation and preamplifier filtering without affecting the noise figure of the system becomes crucial. In addition, passive antenna gain requirements for emergency call applications are generally higher than those of regular dual-band cellular phone antennas. To satisfy all these requirements, a multiple-element antenna is designed, built, and measured.

24 citations


Patent
Takeaki Itsuji1
21 May 2007
TL;DR: An antenna oscillator includes a first strip line type resonator and a second resonator functioning as an antenna as discussed by the authors, where the first resonator is fabricated by stacking a first conductor onto a grounding conductor with a first dielectric part including a gain part therebetween.
Abstract: An antenna oscillator includes a first strip line type resonator and a second resonator functioning as an antenna. The first resonator is fabricated by stacking a first conductor onto a grounding conductor with a first dielectric part including a gain part therebetween. The second resonator is fabricated by stacking a second conductor, emitting electromagnetic waves to the exterior, onto the first resonator with a second dielectric part therebetween so as to function as an antenna with the configuration between the grounding conductor and the second conductor. The first conductor and the second conductor are separated from each other in a stacking direction with the second dielectric part or the second dielectric part and the grounding conductor therebetween. The first resonator and the second resonator are electromagnetically connected together so as to form a resonance circuit that makes the electromagnetic waves resonate.

Journal ArticleDOI
TL;DR: In this article, a contactless method of spatially coupling differential signals from a transmission line to an antenna structure is described, where a differential signal is used to generate a current maximum/virtual short circuit under the antenna and electromagnetic energy is efficiently coupled from the transmission line via an aperture.
Abstract: A novel contactless method of spatially coupling differential signals from a transmission line to an antenna structure is described. A differential signal is used to generate a current maximum/virtual short circuit under the antenna and electromagnetic energy is efficiently coupled from the transmission line to the antenna via an aperture. Two different passive microstrip patch antenna designs using this differential aperture coupling technique will be demonstrated. This coupling technique has also been successfully applied in an active integrated differential antenna design. Simulation and measurement results are also presented to validate the coupling concept. A simplified transmission line model has also been developed and successfully used to model the differential aperture coupling technique.

Patent
09 Aug 2007
TL;DR: In this paper, a system for minimizing coupling nulls between an electromagnetic field derived from one or more sources and a plurality of randomly oriented RFID tags, wherein the electromagnetic field is rotated relative to the tags such that no tag is persistently located in a coupling null relative to a field, is presented.
Abstract: A system is disclosed for minimizing coupling nulls between an electromagnetic field derived from one or more sources and a plurality of randomly oriented RFID tags, wherein the electromagnetic field is rotated relative to the tags such that no tag is persistently located in a coupling null relative to the field. The source of the electromagnetic field may include a passive antenna or loop that changes its orientation relative to a direction of movement of the tags. The source of the electromagnetic field may further include an active antenna or loop that is electromagnetically coupled to the passive antenna or loop. A method for minimizing coupling nulls between the electromagnetic field and the randomly oriented tags is also disclosed.

Journal ArticleDOI
TL;DR: In this article, a wideband multifunctional antenna operating as an output matching load of the power transistor and harmonic tuning circuits, as well as a radiator, is designed and fully integrated with a power transistor.
Abstract: A novel approach to enhance power-added efficiency (PAE) bandwidth and transmitting power bandwidth of the fully integrated transmitter front-end is proposed. To obtain these characteristics, a wideband multifunctional antenna operating as an output matching load of the power transistor and harmonic tuning circuits, as well as a radiator, is designed and fully integrated with a power transistor. Therefore, the wideband direct integration between the output of the power transistor and input of the antenna can be achieved without any impedance transformers. Under the condition of PAE over 50% and transmitting power within 3 dB for the peak transmitting power at the operating band, the measured PAE bandwidth and transmitting power bandwidth are 930 MHz (from 4.9 to 5.83 GHz) and 1030 MHz (from 4.8 to 5.83 GHz), respectively. About a half size is also obtained compared with the conventional wideband class F active antenna for high PAE, and the second and third harmonic radiations of the proposed structure for the normalized peak power of the fundamental frequency are measured less than -30 and -40 dB in all directions, respectively

Proceedings ArticleDOI
09 Jun 2007
TL;DR: In this paper, the fork antenna is compared to the big-blade antenna in terms of performance and power consumption, and it is shown through simulation and field measurement that fork antenna compares closely in performance to big-bladed antenna and is therefore a viable alternative to big blade antenna.
Abstract: The Long Wavelength Array (LWA), currently in the development stage, is a radio telescope array that will be constructed in New Mexico, USA over the next several years. It will consist of ~ 52 stations of ~ 256 cross-dipole antennas each, and will explore the Universe in the 20 - 80 MHz frequency band. The large number of antennas required for the LWA suggests that the antenna design must be kept simple in order to maintain a low station cost. The leading candidate LWA antenna is a "big blade" antenna consisting of crossed dipole elements made of sheet aluminum. The big blade antenna has been extensively characterized and shows potential for fulfilling the technical requirements for the LWA. However, their potentially prohibitive cost has necessitated the exploration of alternate, more affordable antenna topologies. In this paper, we present one such promising topology - the fork antenna. In the following sections, we show through simulation and field measurement that the fork antenna compares closely in performance to the big blade antenna and is therefore a viable alternative to the big blade antenna in the LWA project.

Proceedings ArticleDOI
21 Nov 2007
TL;DR: This paper reviews advances in vehicle mounted antennas developed into a long term R&D program in collaboration between the ASK Industries Group and the Microwave and Antenna Laboratory (LAM) of the University of Florence.
Abstract: This paper reviews advances in vehicle mounted antennas developed into a long term R&D program in collaboration between the ASK Industries Group and the Microwave and Antenna Laboratory (LAM) of the University of Florence. Today an ever-increasing number of radio services have become available, therefore multifunction, multiband antenna systems are required. Examples are made of recently developed wideband, multi-band and multi-function automotive passive and active antenna systems for roof and internal mounting, designed to satisfy various attendant features such as compactness, radiation efficiency, robustness, aesthetic and aerodynamic profile and a low mass-production cost, that after all represents the most stringent requirement.

Journal ArticleDOI
03 Jun 2007
TL;DR: In this article, a planar dielectric resonator (PDR) tuned by a ferroelectric (FE) varactor is presented, which acts both as stabilizing resonator and as a radiator.
Abstract: Design of tunable Gunn diode-based active antenna module including a new type of planar dielectric resonator (PDR) tuned by a ferroelectric (FE) varactor is presented. The module is designed in such a way that the PDR acts both as a stabilizing resonator and as a radiator. Microwave properties of FE elements used for voltage-controlled oscillator (VCO) tuning are considered. The module operates at a frequency around of 17 GHz and demonstrates the radiated power of 8.8plusmn0.1 dBm over the 130-MHz tuning range and a phase-noise level of -80 dBc/Hz at 100-kHz offset. 65deg width of the radiation pattern in both the E-and H-planes corresponding to a gain of 5.1 dBi was measured. The VCO module has been tested in the regime of the frequency modulation. The output signal spectra measured and simulated for modulating bipolar voltage pulses of repetition frequency f=2 MHz are presented.

Patent
30 Mar 2007
TL;DR: In this article, a directive antenna with a ground plate, an active antenna coupled to the ground plate via either a first or second reactive component, and at least one passive antenna coupled with the groundplate via a reactive component is presented.
Abstract: A directive antenna operable in multiple frequency bands includes a ground plate, an active antenna electrically coupled to the ground plate, and at least one passive antenna, coupled to the ground plate via either a first or second reactive component. When the at least one passive antenna is coupled to the ground plate via the first reactive component, an effective length of the at least one passive antenna is increased. When the at least one passive antenna is connected to the ground plate via the second reactive component, an effective length of the at least one passive antenna is decreased.

Journal ArticleDOI
TL;DR: In this article, the use of active antennas in microwave radiometric thermometry is investigated, where prospective applications are within biomedical diagnostics, and it is shown that the temperature accuracy of a broadband radiometer can be improved as a consequence of a smaller overall system noise figure.
Abstract: The use of active antennas in microwave radiometric thermometry is investigated, where prospective applications are within biomedical diagnostics. By incorporating a tiny low-noise amplifier, with only marginal self-heating, in the antenna probe, it is shown that the temperature accuracy of a broadband radiometer can be improved as a consequence of a smaller overall system noise figure. Proof of concept is verified experimentally through increased detectability of a hot object within a lossy medium.

Journal Article
TL;DR: In this article, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB degradation compared to a full-size lossless dipole in urban environments.
Abstract: This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position.The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception.Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.


Journal ArticleDOI
TL;DR: In this paper, the vector fitting (VF) algorithm is applied to the equivalent circuit modelling of an antenna over a broad frequency band to ensure that the resulting circuit model is realizable, the passivity constraint must be imposed during the modelling process.
Abstract: The vector fitting (VF) algorithm is applied to the equivalent circuit modelling of an antenna over a broad frequency band. To ensure that the resulting circuit model is realisable, the passivity constraint must be imposed during the modelling process. Three methods are investigated to ensure the passivity, each based on VF: (i) the use of quadratic programming proposed earlier by Gustavsen and Semlyen, (ii) a technique based on constraining a second-order rational function and (iii) a search method using a particle swarm optimisation with constraints. These techniques are evaluated through three sample antennas: a commercial broadband horn, an ultra-wideband planar monopole with a notch-band and an active integrated microstrip antenna. The results are compared in terms of the modelling error against the model order and the computation time required.

Proceedings ArticleDOI
01 Jan 2007
TL;DR: An active circulator is presented in this paper to be integrated with a patch antenna that tries to overcome the non reciprocity behaviour of active antenna in a compact way.
Abstract: An active circulator is presented in this paper to be integrated with a patch antenna. This antenna tries to overcome the non reciprocity behaviour of active antenna in a compact way. (5 pages)

Proceedings ArticleDOI
01 Jan 2007
TL;DR: In this article, the co-design between an antenna and a low noise amplifier (LNA) is addressed over an ultra wide frequency bandwidth: 31-51 GHz, where the antenna input impedance has no more to fit constant and real impedance on the whole bandwidth.
Abstract: The co-design between an antenna and a low noise amplifier (LNA) is here addressed over an ultra wide frequency bandwidth: 31-51 GHz The key idea of co-design is to relax the 50 Ω impedance matching constraint on both LNA and antenna thanks to joint conception in order to improve performances for a given power budget On LNA side, the co-design benefits from removing the major part of the costly integrated passive elements serving as a matching circuit The co-designed LNA benefits from a size, cost and noise figure reduction The antenna input impedance has no more to fit constant and real impedance on the whole bandwidth In the present case, this point is used to reduce dimensions To quantify performance enhancement the followed strategy consists in comparing a classical 50 Ω and a co-designed active antenna design approach, with the same LNA architecture, the same power consumption and the same antenna kind (5 pages)

Proceedings ArticleDOI
01 Jan 2007
TL;DR: A ferrite loaded multi-turn loop antenna is proposed and evaluated for reception of FM radio in mobile phones with a G/T degradation compared to an ideal dipole antenna in a realistic urban environment of less than 23 dB over the entire FM band 88 - 108 MHz.
Abstract: A ferrite loaded multi-turn loop antenna is proposed and evaluated for reception of FM radio in mobile phones. By co- designing the antenna element with an amplifier and using varactor diodes for frequency tuning, a G/T degradation compared to an ideal dipole antenna in a realistic urban environment of less than 23 dB over the entire FM band 88 - 108 MHz has been achieved. The antenna element occupies 1.5 cm3 and the circuits' uses 1.5 cm2 PCB area. Theoretical and experimental results are presented together with design choice motivations and measurement procedures, including isolation measurements from a co-located GSM transmit antenna. (10 pages)

Journal ArticleDOI
G. Yun1
TL;DR: A diamond-shaped microstrip ring patch, as a radiator of an oscillator-type active antenna, is proposed for easier impedance matching, smaller patch size, and circular polarisation as mentioned in this paper.
Abstract: A diamond-shaped microstrip ring patch, as a radiator of an oscillator-type active antenna, is proposed for easier impedance matching, smaller patch size, and circular polarisation. The active antenna has been built and measured. The fabricated antenna including the active circuitry has a size about 65% of that using a regular-size square microstrip antenna. Test results show potential possibilities for use as a transmitter of an RFID reader around 915 MHz

Patent
Naoki Okazaki1
12 Sep 2007
TL;DR: An information management system, livestock management system and cages with which chickens can be managed as individual units is described in this article, where a tag reader 8 communicates with a transponder 5 attached to chicken 2 in cage 1 through a passive antenna disposed on one surface of cage 1 so that the distance from transPonder 5 is within a first predetermined distance and an active antenna 7 disposed on automatic feeder 4 so that distance from passive antenna 6 when closest is within another predetermined distance whereby power can be supplied using electromagnetic coupling.
Abstract: An information management system, livestock management system and cages with which chickens can be managed as individual units. A tag reader 8 communicates with a transponder 5 attached to chicken 2 in cage 1 through a passive antenna disposed on one surface of cage 1 so that the distance from transponder 5 is within a first predetermined distance and an active antenna 7 disposed on automatic feeder 4 so that the distance from passive antenna 6 when closest is within a second predetermined distance whereby power can be supplied using electromagnetic coupling, and reads management information for chicken 2 from transponder 5 or writes it to transponder 5 . This information management system can be used for other livestock and for other moving objects.

Patent
16 Mar 2007
TL;DR: In this article, an active antenna capable of transmitting and receiving a wireless signal of a low frequency band and a mobile communication terminal having the active antenna, is provided, which includes an antenna element which transmits and receives wireless signal, a filter which filters the wireless signal being received at the antenna element, and an amplifier which amplifies the wireless signals being passed through the filter.
Abstract: An active antenna capable of transmitting and receiving a wireless signal of a low frequency band and a mobile communication terminal having the active antenna, are provided. The active antenna includes an antenna element which transmits and receives a wireless signal, a filter which filters the wireless signal being received at the antenna element such that a wireless signal belonging to a frequency band lower than the operating frequency of the antenna element is passed, and an amplifier which amplifies the wireless signal being passed through the filter. As a result, the size of the antenna can be greatly reduced, by the use of an active antenna which receives wireless signals of low frequency bands. Additionally, a more compact mobile communication terminal can be provided, because wireless signal of both high frequency bands and low frequency bands can be transmitted and received at one antenna.

Journal ArticleDOI
TL;DR: In this article, the frequency agility is achieved by symmetrical loading of two identical MOS capacitors at the radiating edge of the patch, in which the operating frequency of the rectangular microstrip antenna is electronically controlled by the bias voltage of MOS capacitor.
Abstract: A new technique for designing the frequency agile microstrip antenna is presented. The frequency agility is achieved by symmetrical loading of two identical MOS capacitors at the radiating edge of the patch, in which the operating frequency of the rectangular microstrip antenna is electronically controlled by the bias voltage of MOS capacitors. Theoretical model for the antenna is developed using modal cavity model approach and results are also simulated with MOM based simulator. The tuning range is found to be 1.527 GHz (61.09%), which is much better than earlier reported data and the unloaded patch radiator. Antenna shows consistent return loss and radiation pattern for the entire tunable frequency range. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 431–434, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22174

Journal ArticleDOI
TL;DR: In this paper, the feasibility of creating an ultra-wideband receiving antenna comprising a dipole loaded on an active element based on field effect transistors is analyzed, which is intended for registration of waveforms and measurement of instantaneous electric field strengths for electromagnetic radiation pulses of nanosecond and subnanosecond durations.
Abstract: The feasibility of creating an ultra-wideband receiving antenna comprising a dipole loaded on an active element based on field-effect transistors is analyzed. The antenna is intended for registration of waveforms and measurement of instantaneous electric field strengths for electromagnetic radiation pulses of nanosecond and subnanosecond durations.