A Quasi-Lumped Element Series Array Resonator Antenna

This paper presents a 6-element series array quasi-lumped element resonator antenna. The proposed antenna employs an interdigital capacitor in parallel with a straight strip conductor whose centre finger is shorted across the capacitor. An array configuration is imperative as the gain of a single quasi-lumped element arrangement was only moderate and specifically put at about 9.4 dBi which may not be adequate for long distance communications. Relevant Equations for radiation pattern of the quasi-lumped element resonator (QLER) were derived and presented. The proposed antenna array exhibits a gain enhancement up to about 29.47% with a noticed size reduction of 80 × 30 sq. mm. Compared to standard long wire antenna and other approaches of capacitive loaded long wire antennas, it was proved that the proposed antenna has a relatively better performance yet with significant size reduction. Consequently, it is an ideal candidate for MMIC designs and wireless communication applications

Design And Analysis Of Reconfigurable Sensing Antennas For Wireless Sensing Applications

Reconfiguration sensing antenna (rsa) is a novel antenna concept, which not only can transmit or receive radio waves but also can sense the surrounding environment. The environment sensing is realized by reconfiguring the antenna\u27s characteristics, such as resonant frequency, and radar cross section (rcs). The rsas possess the advantages of passive and low cost, which make them suitable for the large-scale wireless sensing networks (wsns) deployment. In this dissertation, the rsas concept is demonstrated, and two sensing mechanisms performed in the rsas are investigated. In order to verify these sensing mechanisms, four rsas are designed, analyzed, and measured. All the rsa designs in this dissertation are temperature monitoring rsas, and they realize the temperature sensing by reconfiguring the antenna resonant frequency. About the two sensing mechanisms, one utilizes the electrical properties of materials, and the other utilizes thermal properties of the materials. For each sensing mechanism, there are two rsa designs using different sensing materials. As sensing antennas, sensitivity is a crucial factor in the rsa designs. Thus, a sensitivity evaluation method is also defined in this dissertation. There are three factors used to evaluate the rsa performance, which are realized gain, and realized gain bandwidth. For the sensing mechanism using electrical properties of materials, water and high density polyethylene-ba0.3sr0.7tio3 (hdpe-bst) are investigated and selected as the sensing materials. Patch antennas are properly designed to easily implement these sensing materials as their substrate. Simulation and measurement results show that these two designs provide 4mhz/10â°c and 8mhz/10â°c frequency shift with temperature, respectively. Their realized gain is -3.2db with 4.33

A Capacitively loaded Antenna for use in Mobile Handsets

YesA tuneable slotted patch antenna design is presented and verified for use in the DCS, PCS and UMTS bands. The tuning circuit consists of two varactor diodes with some passive components, and is integrated fully with the r radiator patch, with the varactors occupying different locations over the slot. The tuning does not require any further modification to the patch or feed geometry. Good agreement is observed between the predicted and observed impedance bandwidth, return loss, gain and radiation pattern, throughout the range 1.70 GHz-2.05 GHz

Passive devices for UWB systems

Postprint (published version

A Tri-band-notched UWB Antenna with Low Mutual Coupling between the Band-notched Structures

A compact printed U-shape ultra-wideband (UWB) antenna with triple band-notched characteristics is presented. The proposed antenna, with compact size of 24×33 mm2, yields an impedance bandwidth of 2.8-12GHz for VSWR<2, except the notched bands. The notched bands are realized by introducing two different types of slots. Two C-shape half-wavelength slots are etched on the radiating patch to obtain two notched bands in 3.3-3.7GHz for WiMAX and 7.25-7.75GHz for downlink of X-band satellite communication systems. In order to minimize the mutual coupling between the band-notched structures, the middle notched band in 5-6GHz for WLAN is achieved by using a U-slot defected ground structure. The parametric study is carried out to understand the mutual coupling. Surface current distributions and equivalent circuit are used to illustrate the notched mechanism. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is suitable and a good candidate for UWB applications

Mutual coupling reduction of two PIFAs with a T-shape slot impedance transformer for MIMO mobile terminals

Abstract in UndeterminedAn efficient technique is introduced to reduce mutual coupling between two closely spaced PIFAs for MIMO mobile terminals. The proposed mutual coupling reduction method is based on a T-shape slot impedance transformer and can be applied to both single-band and dual-band PIFAs. For the proposed single-band dual PIFAs, the 10 dB impedance bandwidth covers the 2.4 GHz WLAN band (2.4–2.48 GHz), and within the WLAN band an isolation of over 20 dB is achieved. Moreover, the dual-band version covers both the WLAN band and the WiMAX band of 3.4–3.6 GHz, with isolations of over 19.2 dB and 22.8 dB, respectively. The efficiency, gain and radiation patterns of the two-PIFA prototypes are verified in measurements. Due to very low pattern correlation and very good matching and isolation characteristics, the capacity performances are mainly limited by radiation efficiency. The single-band and dual-band PIFAs are also studied with respect to their locations on the ground plane. An eight-fold increase in the bandwidth of one PIFA is achieved, when the single-band PIFAs are positioned at one corner of the ground plane, with the bandwidth of the other PIFA and the good isolation unchanged

A compact high gain dual-band antenna array for WLAN applications

The continuously growing number of wireless devices and the demand for wireless local area network (WLAN) coverage received a lot of research and design attention during the past decade. The WLAN application is a popular dual-band IEEE standard, which operates in two distinct bands with a large centre frequency ratio. This dissertation presents the design and performance of a compact, high gain, dual-band and directional antenna array meant to be used for such applications. The low band, as stated by the IEEE 802.11b standard, covers the frequency range of 2.400 GHz to 2.484 GHz, and the high band is defined by IEEE 802.11a and starts at 5.150 GHz and stops at 5.850 GHz. The frequency ratio between the centres of the two bands is 2.25:1 and is considered a large ratio. The antenna array design is based on an existing dual-band antenna configuration. A parametric study was conducted on the antenna configuration features to obtain a detailed understanding of the antenna performance changes in relation to the physical parameters. The original design was modified to obtain a new sub-array design which can be used in an array for higher gain performance. The sub-array antenna element consists of one capacitively loaded dipole for the lower 2.4 GHz band and four smaller rectangular dipoles for the high 5.5 GHz band. The low band dipole is fed with a microstrip line whereas the four high band dipoles are fed with a slot line. Four of these sub-array antenna elements are configured into an array for increased gain performance. The final gain of the antenna array was measured as 12 dBi at the 2.4 GHz band and 16 dBi at the 5.5 GHz band. The radiation patterns of both the low and high bands have side lobes 10 dB below the main lobe and front to back lobe ratios of at least 17 dB. The volume of the final antenna is 128 _ 128 _ 12 mm3 and is compact compared to other dual-band antenna arrays. The continuously growing number of wireless devices and the demand for wireless local area network (WLAN) coverage received a lot of research and design attention during the past decade. The WLAN application is a popular dual-band IEEE standard, which operates in two distinct bands with a large centre frequency ratio. This dissertation presents the design and performance of a compact, high gain, dual-band and directional antenna array meant to be used for such applications. The low band, as stated by the IEEE 802.11b standard, covers the frequency range of 2.400 GHz to 2.484 GHz, and the high band is defined by IEEE 802.11a and starts at 5.150 GHz and stops at 5.850 GHz. The frequency ratio between the centres of the two bands is 2.25:1 and is considered a large ratio. The antenna array design is based on an existing dual-band antenna configuration. A parametric study was conducted on the antenna configuration features to obtain a detailed understanding of the antenna performance changes in relation to the physical parameters. The original design was modified to obtain a new sub-array design which can be used in an array for higher gain performance. The sub-array antenna element consists of one capacitively loaded dipole for the lower 2.4 GHz band and four smaller rectangular dipoles for the high 5.5 GHz band. The low band dipole is fed with a microstrip line whereas the four high band dipoles are fed with a slot line. Four of these sub-array antenna elements are configured into an array for increased gain performance. The final gain of the antenna array was measured as 12 dBi at the 2.4 GHz band and 16 dBi at the 5.5 GHz band. The radiation patterns of both the low and high bands have side lobes 10 dB below the main lobe and front to back lobe ratios of at least 17 dB. The volume of the final antenna is 128 _ 128 _ 12 mm3 and is compact compared to other dual-band antenna arrays. The continuously growing number of wireless devices and the demand for wireless local area network (WLAN) coverage received a lot of research and design attention during the past decade. The WLAN application is a popular dual-band IEEE standard, which operates in two distinct bands with a large centre frequency ratio. This dissertation presents the design and performance of a compact, high gain, dual-band and directional antenna array meant to be used for such applications. The low band, as stated by the IEEE 802.11b standard, covers the frequency range of 2.400 GHz to 2.484 GHz, and the high band is defined by IEEE 802.11a and starts at 5.150 GHz and stops at 5.850 GHz. The frequency ratio between the centres of the two bands is 2.25:1 and is considered a large ratio. The antenna array design is based on an existing dual-band antenna configuration. A parametric study was conducted on the antenna configuration features to obtain a detailed understanding of the antenna performance changes in relation to the physical parameters. The original design was modified to obtain a new sub-array design which can be used in an array for higher gain performance. The sub-array antenna element consists of one capacitively loaded dipole for the lower 2.4 GHz band and four smaller rectangular dipoles for the high 5.5 GHz band. The low band dipole is fed with a microstrip line whereas the four high band dipoles are fed with a slot line. Four of these sub-array antenna elements are configured into an array for increased gain performance. The final gain of the antenna array was measured as 12 dBi at the 2.4 GHz band and 16 dBi at the 5.5 GHz band. The radiation patterns of both the low and high bands have side lobes 10 dB below the main lobe and front to back lobe ratios of at least 17 dB. The volume of the final antenna is 128 _ 128 _ 12 mm3 and is compact compared to other dual-band antenna arrays.Dissertation (MEng)--University of Pretoria, 2019.TM2019Electrical, Electronic and Computer EngineeringMEngUnrestricte

A compact dual-circularly polarized cavity-backed ring-slot antenna

Dual-circularly polarized antennas usually consist of a radiating structure and a feed network capable of generating the �90� modes required for dual circular polarization. The problem is that these feed networks often take up a large amount of space. It was found that a compact dual-circularly polarized antenna could be made by placing a reduced-size hybrid coupler on top of the center conductor of a ring-slot antenna. Two cavity-backed ring-slot antennas are presented with unidirectional radiation properties. The first is a linearly polarized CPW-fed ring-slot antenna. A T-shaped CPW feed was used to capacitively excite the ring-slot structure. The bottom of the cavity is formed by an AMC reflector consisting of an array of rectangular patches, a substrate and an electric ground plane. Experimental results for the final antenna design with a size of 0.457_0 _ 0.457_0 _ 0.056_0 exhibits a 5.5% impedance bandwidth, maximum gain of approximately 7 dBi, a front-to-back ratio of 15 dB, and good cross-polarization. In the second design a reduced-size microstrip branch-line coupler was placed on top of the center conductor of the ring-slot in order to feed two T-shaped microstrip feedlines, in order to achieve dual circular polarization. Two coaxial cables were used to feed the branch-line coupler from the back of the structure. This resulted in a significantly better front-to-back ratio. Experimental results for the final antenna design with a size of 0.5_0 _ 0.5_0 _ 0.056_0, exhibits a 4% isolation bandwidth, 12% impedance bandwidth, maximum gain of approximately 6.8 dBic, and good cross-polarization and axial ratio results were achieved. If the branch-line coupler is removed, dual-linear polarization can be achieved. This makes the antenna polarization diverse. Future work will focus on improving the isolation bandwidth without significantly increasing the overall size of the antenna. These antennas are simple to manufacture using simple photolithography as no shorting posts or solid sidewalls are necessary. It can potentially be used as a flush-mounted single radiator or as an element for an array. This polarization-diverse small-footprint and lowprofile antenna with relatively high gain is a good candidate for 2.4 GHz WLAN applications.Dissertation (MEng)--University of Pretoria, 2018.Electrical, Electronic and Computer EngineeringMEngUnrestricte

Käsipuhelinantennien miniatyrisointimenetelmät

Tässä diplomityössä tutkittiin pienten antennien miniatyrisointimenetelmiä. Tärkeimmät käsipuhelinantenneille asetetut vaatimukset ovat laajakaistaisuus, suuri säteilyhyötysuhde sekä pieni koko. Pienentämisen ongelma on näiden vaatimusten keskinäinen suhde; yhden ominaisuuden parantaminen tapahtuu aina jonkin toisen kustannuksella. Työssä havaittiin, että eri miniatyrisointimenetelmiä soveltamalla voidaan vaikuttaa em. ominaisuuksien jakautumiseen. Aluksi työssä käytiin lyhyesti läpi pienten antennien teoriaa sekä selvitettiin matkapuhelinantenneille asetettuja vaatimuksia. Seuraavaksi esiteltiin muutaman käsipuhelimen sisäiseksi antenniksi soveltuvan antennityypin ominaisuuksia. Käsitellyt antennityypit olivat dielektrinen resonaattoriantenni ja PIFA-antenni (mikroliuska-antenni). Tämän jälkeen tutkittiin eri miniatyrisointitekniikoita ja niiden soveltamista edellä esiteltyihin antennityyppeihin. Useita antenneja tutkittiin kokeellisesti. Tavallisten impedanssi- ja säteilyominaisuuksien lisäksi mitattiin prototyyppien säteilyhyötysuhteet. Miniatyrisointi dielektrisesti kuormittamalla todettiin tehokkaaksi dielektristen resonaattoriantennien yhteydessä, mutta työssä toteutetulle erittäin ohuelle mikroliuska-antennille, jossa on enemmän metalliosia, tämä menetelmä ei sovi. Korkeapermittiivisen materiaalin lisääminen tällaiseen rakenteeseen heikensi antennin säteilyominaisuuksia aiheuttaen metallihäviöiden suhteellisen osuuden voimakkaan kasvun. Tämä johti hyvin huonoon hyötysuhteeseen. PlFA-antennin resistiivinen kuormittaminen lisäsi huomattavasti kaistanleveyttä, mutta tämä tapahtui selvästi säteilytehokkuuden kustannuksella. Muut PIFA-antenneille sovelletut menetelmät huomattiin kokonaisvaikutuksiltaan melko yhdenvertaisiksi. Reaktiivisesti kuormittamalla saavutettiin korkea säteilyhyötysuhde, mutta antennin koon pienentyessä menetettiin samalla kaistanleveyttä. Sama ilmiö havaittiin hidasaaltorakenteissa