Preface. 1. Introduction and Overview. 1.1 Introduction. 1.2 Compact Microstrip Antennas. 1.3 Compact Broadband Microstrip Antennas. 1.4 Compact Dual-Frequency Microstrip Antennas. 1.5 Compact Dual-Polarized Microstrip Antennas. 1.6 Compact Circularly Polarized Microstrip Antennas. 1.7 Compact Microstrip Antennas with Enhanced Gain. 1.8 Broadband Microstrip Antennas. 1.9 Broadband Dual-Frequency and Dual-Polarized Microstrip Antennas. 1.10 Broadband and Dual-Band Circularly Polarized Microstrip Antennas. 2. Compact Microstrip Antennas. 2.1 Introduction. 2.2 Use of a Shorted Patch with a Thin Dielectric Substrate. 2.3 Use of a Meandered Patch. 2.4 Use of a Meandered Ground Plane. 2.5 Use of a Planar Inverted-L Patch. 2.6 Use of an Inverted U-Shaped or Folded Patch. 3. Compact Broadband Microstrip Antennas. 3.1 Introduction. 3.2 Use of a Shorted Patch with a Thick Air Substrate. 3.3 Use of Stacked Shorted Patches. 3.4 Use of Chip-Resistor and Chip-Capacitor Loading Technique. 3.5 Use of a Slot-Loading Technique. 3.6 Use of a Slotted Ground Plane. 4. Compact Dual-Frequency and Dual-Polarized Microstrip Antennas. 4.1 Introduction. 4.2 Some Recent Advances in Regular-Size Dual-Frequency Designs. 4.3 Compact Dual-Frequency Operation with Same Polarization Planes. 4.4 Compact Dual-Frequency Operation. 4.5 Dual-Band or Triple-Band PIFA. 4.6 Compact Dual-Polarized Designs. 5. Compact Circularly Polarized Microstrip Antennas. 5.1 Introduction. 5.2 Designs with a Cross-Slot of Unequal Arm Lengths. 5.3 Designs with a Y-Shaped Slot of Unequal Arm Lengths. 5.4 Designs with Slits. 5.5 Designs with Spur Lines. 5.6 Designs with Truncated Corners. 5.7 Designs with Peripheral Cuts. 5.8 Designs with a Tuning Stub. 5.9 Designs with a Bent Tuning Stub. 5.10 Compact CP Designs with an Inset Microstrip-Line Feed. 6. Compact Microstrip Antennas with Enhanced Gain. 6.1 Introduction. 6.2 Compact Microstrip Antennas with High-Permittivity Superstrate. 6.3 Compact Microstrip Antennas with Active Circuitry. 7. Broadband Microstrip Antennas. 7.1 Introduction. 7.2 Use of Additional Microstrip Resonators. 7.3 Microstrip Antennas with an Air Substrate. 7.4 Broadband Slot-Loaded Microstrip Antennas. 7.5 Broadband Microstrip Antennas with an Integrated Reactive Loading. 7.6 Broadband Microstrip Antennas with Reduced Cross-Polarization Radiation. 8. Broadband Dual-Frequency and Dual-Polarized Microstrip Antennas. 8.1 Introduction. 8.2 Broadband Dual-Frequency Microstrip Antennas. 8.3 Broadband Dual-Polarized Microstrip Antennas. 9. Broadband and Dual-Band Circularly Polarized Microstrip Antennas. 9.1 Introduction. 9.2 Broadband Single-Feed Circularly Polarized Microstrip Antennas. 9.3 Broadband Two-Feed Circularly Polarized Microstrip Antennas. 9.4 Broadband Four-Feed Circularly Polarized Microstrip Antennas. 9.5 Dual-Band Circularly Polarized Microstrip Antennas. Index.

Compact and Broadband Microstrip Antennas

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

Core–shell composites, Fe3O4@C, with 500 nm Fe3O4 microspheres as cores have been successfully prepared through in situ polymerization of phenolic resin on the Fe3O4 surface and subsequent high-temperature carbonization. The thickness of carbon shell, from 20 to 70 nm, can be well controlled by modulating the weight ratio of resorcinol and Fe3O4 microspheres. Carbothermic reduction has not been triggered at present conditions, thus the crystalline phase and magnetic property of Fe3O4 micropsheres can be well preserved during the carbonization process. Although carbon shells display amorphous nature, Raman spectra reveal that the presence of Fe3O4 micropsheres can promote their graphitization degree to a certain extent. Coating Fe3O4 microspheres with carbon shells will not only increase the complex permittivity but also improve characteristic impedance, leading to multiple relaxation processes in these composites, thus the microwave absorption properties of these composites are greatly enhanced. Very inte...

Shell thickness-dependent microwave absorption of core-shell Fe3O4@C composites.

Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. By Christophe Caloz and Tatsuo Itoh.

The MgAl2O4 ceramics were prepared by the conventional solid-state ceramic route and the dielectric properties studied in the microwave frequency region (3–13 GHz). The phase purity and crystal structure were identified using the X-ray diffraction technique. The MgAl2O4 spinel ceramics show interesting microwave dielectric properties (er=8.75, Quxf=68900 GHz (loss tangent = 0.00017 at 12.3 GHz), τf=-75 ppm/°C). The MgAl2O4 has high negative τf, which precludes its immediate use in practical applications. Hence the microwave dielectric properties of MgAl2O4 spinels were tailored by adding different mole fractions of TiO2. The er and Q factor of the mixed phases were increased with the molar addition of TiO2 into the spinel to form mixtures based on (1-x)MgAl2O4-xTiO2 (x=0.0-1.0). For x=0.25 in (1-x)MgAl2O4-xTiO2, the microwave quality factor reaches a maximum value of Quxf=105400 GHz (loss tangent = 0.00007 at 7.5 GHz) where er and τf are 11.035 and -12 ppm/°C, respectively. The microwave dielectric properties of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is superior to several commercially available low loss dielectric substrates.

/pdf/1-x-mgal2o4-xtio2-dielectrics-for-microwave-and-millimeter-224845g5ns.pdf

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

A dual wide-band CPW-fed modified Koch fractal printed slot antenna, suitable for WLAN and WiMAX operations, is proposed in this paper. Here, the operating frequency of a triangular slot antenna is lowered by the Koch iteration technique resulting in a compact antenna. Studies on the impedance and radiation characteristics of the proposed antenna indicate that a modified Koch fractal slot antenna has an impedance bandwidth from 2.38 to 3.95 GHz and 4.95-6.05 GHz covering 2.4/5.2/5.8 GHz WLAN bands and the 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Empirical relations are deduced and compared with the results.

CPW-Fed Koch Fractal Slot Antenna for WLAN/WiMAX Applications

A compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna, with high isolation, is proposed for portable UWB MIMO systems. Two coplanar stripline-fed staircase-shaped radiating elements are connected back-to-back. The prototype is designed on a substrate of dielectric constant 4.4 with an overall dimension of $25\,\mathrm{mm}\times 30\,\mathrm{mm}\times 1.6\,\mathrm{mm}$ . This antenna configuration with an isolating metal strip placed in between the two radiating elements ensures high isolation in the entire UWB band. The proposed antenna exhibits a good 2:1 VSWR impedance bandwidth covering the entire UWB band ( $3.1{-}10.6\,\mathrm{GHz}$ ) with a high isolation better than 20 dB, peak gain of 5.2 dBi, peak efficiency of 90%, and guaranteed value of envelope correlation coefficient (ECC) ${\leq}0.1641$ .

A Compact UWB MIMO Antenna With Reflector to Enhance Isolation

A novel compact microstrip fed dual-band coplanar antenna for wireless local area network is presented. The antenna comprises of a rectangular center strip and two lateral strips printed on a dielectric substrate and excited using a 50 Omega microstrip transmission line. The antenna generates two separate resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. Lower resonant mode of the antenna has an impedance bandwidth (2:1 VSWR) of 330 MHz (2190-2520 MHz), which easily covers the required bandwidth of the 2.4 GHz WLAN, and the upper resonant mode has a bandwidth of 1.23 GHz (4849-6070 MHz), covering 5.2/5.8 GHz WLAN bands. The proposed antenna occupy an area of 217 mm2 when printed on FR4 substrate (epsivr=4.7). A rigorous experimental study has been conducted to confirm the characteristics of the antenna. Design equations for the proposed antenna are also developed

A New Compact Microstrip-Fed Dual-Band Coplanar Antenna for WLAN Applications

The design of a compact, single feed, dual frequency dual polarized and electronically reconfigurable microstrip antenna is presented in this paper. A square patch loaded with a hexagonal slot having extended slot arms constitutes the fundamental structure of the antenna. The tuning of the two resonant frequencies is realized by varying the effective electrical length of the slot arms by embedding varactor diodes across the slots. A high tuning range of 34.43% (1.037–1.394 GHz) and 9.27% (1.359–1.485 GHz) is achieved for the two operating frequencies respectively, when the bias voltage is varied from 0 to −30 V. The salient feature of this design is that it uses no matching networks even though the resonant frequencies are tuned in a wide range with good matching below −10 dB. The antenna has an added advantage of size reduction up to 80.11% and 65.69% for the two operating frequencies compared to conventional rectangular patches.

/pdf/design-of-compact-reconfigurable-dual-frequency-microstrip-4d4eb30tuf.pdf

Pezholil Mohanan

Papers

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

CPW-Fed Koch Fractal Slot Antenna for WLAN/WiMAX Applications

A Compact UWB MIMO Antenna With Reflector to Enhance Isolation

A New Compact Microstrip-Fed Dual-Band Coplanar Antenna for WLAN Applications

Design of compact reconfigurable dual frequency microstrip antennas using varactor diodes