http://ieeexplore.ieee.org TOC Alert for Publication# 8 2012 February 10 60 2 C1 718 151 60 2 C2 C2 48 $0.16 lambda$ and $0.03 lambda$ at the minimum operation frequency respectively, are less than 2 over a 17:1 octave bandwidth, and the horizontal gains of the antenna are between 4.2 dB and 6.8 dB. Thanks to its high gain, broadband and low reflection, the proposed double-whip antenna in this paper is ideal for application in vehicle wireless communication.]]> 60 2 719 724 1025 ${rm TE}_{00}$ mode, slowly tapers into a “gapped” H-guide, or dielectrically guided horn, where a large air gap separates the center dielectric and metallic plates. A wideband Bézier shaped microstrip to H-guide transition feeding structure is fabricated using a low loss Rogers 5880 substrate and integrated with the proposed antenna. The fabricated prototype operates from 8 to 16 GHz with a peak gain of approximately 16 dBi.]]> 60 2 725 734 2099 $1.02lambda_{0}times 0.82lambda_{0}times 0.063lambda_{0}$), mounted on a $1.5lambda_{0}times 1.5lambda_{0}$ back plate, exhibit a 5% impedance bandwidth, maximum gain in excess of 10 dBi, low cross-polarization, and a front-to-back ratio of approximately 25 dB. This low-profile antenna with relatively high gain could be a good candidate for a 2.4 GHz WLAN application.]]> 60 2 735 742 2363 $vert {rm S}_{11}vert < -10$ dB) across the operating frequency bands of all three EBG resonator antennas. Experimental results confirm the wideband performance of a simple, low-profile EBG resonator antenna. Its PRS thickness is only 1.6 mm, effective bandwidth is 12.6%, measured peak gain is 16.2 dBi at 11.5 GHz and 3 dB gain bandwidth is 15.7%.]]> 60 2 743 750 1063 $TM_{011}$ mode of a cylindrical DRA. The DRA radiates like an electric monopole, generating omnidirectional linearly polarized (LP) fields. Based on this LP design, a novel omnidirectional circularly polarized (CP) DRA is studied for the first time. Slots are introduced to the sidewalls of the DRA, exciting a degenerate mode for the generation of CP fields. To demonstrate the idea, an omnidirectional CP DRA was designed for WLAN (2.4–2.48 GHz) applications. The reflection coefficient, axial ratio (AR), radiation pattern, and antenna gain are studied, and reasonable agreement between the measured and simulated results is observed.]]> 60 2 751 759 810 $^{circ}$ linearly polarized waves. Its dispersion, Bloch impedance and radiation characteristics are extracted by applying a comprehensive analysis on the unit cell. Its backfire-to-endfire beam-steering capability through frequency scanning due to the CRLH nature is demonstrated and discussed. It is able to generate arbitrary different polarization states by changing the way of excitation, including linear polarization (LP) and circular polarization (CP). This leaky TL is fabricated by the standard printed-circuit board process. Two broadband couplers are also designed and fabricated for the specified excitation purpose. Six different polarization states, including four LP cases and two CP ones, are experimentally verified. The propagation and radiation parameters, including the S-parameters, radiation patterns, gain, and axial ratio (for CP states) are presented for these modes. Measured results are consistent with the simulation. The proposed LW structure shows some desirable merits, such as the simplicity in design, low-cost fabrication, and beam-steering and polarization-flexible capabilities, providing a high degree of flexibility for the real application.]]> 60 2 760 771 2950 60 2 772 785 3714 ${- 20}~{rm dB}$ compared with the mentioned co-polar CP gains in both bands. The isolations between the two ports are about 25 dB and 38 dB, at 920 MHz and 2.45 GHz, respectively. The measured axial ratios are less than 0.7 dB in the UHF band (917–923 MHz) and 1.5 dB in the ISM band (2.4–2.48 GHz).]]> 60 2 786 791 938 $S$-band for space missions. The bandwidth enlargement is obtained by stacking two FP cavities of different size, each of them presenting a low quality factor. Their radiating apertures measure around $lambda_{0}$ and 2 $,timeslambda_{0}$, respectively. Concentric corrugations are also introduced between both cavities to control the higher-order modes that are excited systematically in shielded small-size FP antennas due to lateral resonances. The obtained results are compared to those of a single-stage FP cavity antenna with the same aperture size. Several prototypes have been fabricated and measured. An aperture efficiency higher than 70%, a reflection coefficient smaller than $- $15 dB, and sidelobe levels lower than ${- }$20 dB have been obtained experimentally, over a wide frequency band (2.4–2.66 GHz). These characteristics make stacked FP cavity antennas very attractive to replace global coverage horn antennas, or to be used in feed clusters of multiple-beam antennas, especially in $C$- and $S$-bands, where they lead to more compact and less bulky solutions compared to classical feed horns.]]> 60 2 792 802 2995 60 2 803 810 1973 60 2 811 820 2300 60 2 821 831 3282 60 2 832 839 1760 $times,$ 62 mm $times,$ 25 mm was realized. The characteristic of the PAA was evaluated by calculating the directivity using measured data from the radiator and the feed network. From these considerations, the PAA was found to have the capability of providing a beam tilt angle of ${pm}{18}^{circ}$ while maintaining a gain of more than 32 dBi.]]> 60 2 840 853 3017 $,times$10 element reconfigurable reflectarray antenna operating at 26.5 GHz. The change in the progressive phase shift between the elements is obtained by adjusting the length of the open ended transmission lines in the elements with the RF MEMS switches. The reconfigurable reflectarray is monolithically fabricated with the RF MEMS switches in an area of 42.46 cm $^{2}$ using an in-house surface micromachining and wafer bonding process. The measurement results show that the main beam can be switched between broadside and 40$^{circ}$ in the H-plane at 26.5 GHz.]]> 60 2 854 862 1765 $^{circ}$ angular range in azimuth. This structure is very simple, flexible, and compatible with low-cost manufacturing processes such as printed technology. The proposed design is based on balanced power dividers and combiners arranged in such a way to feed a sector of a circular array antenna with Gaussian amplitude distribution and in-phase signals. The first characteristic provides control on the radiation pattern shape, including main lobe shape and sidelobe level, while the second ensures stable beam pointing over a wide frequency range. The proposed azimuth beamforming network is described, and a specific design in microstrip technology is presented with a center frequency at 6 GHz. Simulation results are supported by the measurement of several prototypes. In particular, two designs including the circular array antenna are compared to investigate the impact of the circular array antenna radius on radiation patterns. Despite the assumptions, good correlation is found between simulation and measurement results, thus confirming the properties of the proposed beamforming network concept. Integration of phase controls in the feeding network and its impact on the overall antenna efficiency are also discussed.]]> 60 2 863 869 977 60 2 870 879 2707 60 2 880 885 1235 60 2 886 894 1981 60 2 895 902 1529 60 2 903 914 3079 60 2 915 921 913 60 2 922 929 1939 60 2 930 940 1768 60 2 941 951 2751 60 2 952 957 1004 60 2 958 963 1061 60 2 964 970 1663 60 2 971 983 3091 60 2 984 996 1597 60 2 997 1008 2502 60 2 1009 1019 1793 60 2 1020 1025 769 60 2 1026 1034 2080 60 2 1035 1042 1368 60 2 1043 1052 2571 60 2 1053 1058 1072 $Ka$ of the proposed design is 0.55 and its measured gain is 1.69 dBi with 78% measured radiation efficiency. The second cube antenna is similar to the first one but it was loaded with high dielectric constant superstrates. $Ka$ of the second proposed antenna is 0.45, its measured gain is 1.25 dBi with 73% measured radiation efficiency and the bandwidth is 1.5%. The designs compare well with high efficiency, electrically small antennas that have been described in the open literature. A Wheeler Cap was used to measure the efficiency and the 3-antenna method was used for measuring the gain.]]> 60 2 1059 1065 1084 60 2 1066 1074 3612 60 2 1075 1083 1425 $({rm MEG}_{rm GPS})$ and GPS Coverage Efficiency $(eta_{c})$.]]> 60 2 1084 1094 2083 60 2 1095 1105 1262 60 2 1106 1113 583 60 2 1114 1125 2179 60 2 1126 1131 1747 60 2 1132 1135 1234 $0.43lambda_{ib}$ (wavelength in-body) and its height is $0.23lambda_{ib}$ which includes substantial insulation. While losses from such a deeply implanted antenna are inevitable, the work presented here shows accurate frequency tuning can be achieved prior to implantation. The relative size, safety of use and results presented here make this pseudo-normal-mode helical antenna an excellent candidate for use with deeply implanted wireless sensors.]]> 60 2 1135 1139 727 60 2 1139 1142 988 ${rm TM}_{01}$ mode radiation, while the normal radiation mode is the ${rm TM}_{10}$ mode. Furthermore, the ${rm TM}_{01}$ mode can be combined with the ${rm TM}_{10}$ mode without a pattern distortion. The hybridization of the two modes yields a wideband property (6.8%) and a unique radiation pattern that is comparable with two independent dipole antennas positioned orthogonally. Also, the proposed antenna achieves high efficiency (96%) and reasonable gain (3.85 dBi), even though the electrical size of the antenna is only $0.24lambda_{0}times 0.24lambda_{0}times 0.02lambda_{0}$.]]> 60 2 1143 1147 972 60 2 1147 1152 255 60 2 1152 1157 1148 60 2 1157 1161 858 60 2 1161 1165 411 60 2 1166 1171 941 60 2 1171 1176 418 60 2 1176 1181 662 60 2 1182 1186 669 ${rm O}(N^{1.5})$ computational complexity and memory requirement, where $N$ is the number of unknowns. Numerical results are presented to validate the efficiency and accuracy of this method through comparison with other rigorous solutions.]]> 60 2 1186 1191 534 $M^{2}$ order 2-dimensional FFT. A combination of these two techniques in the algorithm ensures real ad-hoc design capabilities, reached through analysis speedup. The purpose of the algorithm is to obtain an optimal conformal serrated-edge reflector design through the analysis of the field quality within the quiet zone that it is able to generate in its forward half space.]]> 60 2 1192 1197 651 60 2 1197 1202 305 60 2 1203 1203 122 60 2 1204 1204 320 60 2 C3 C3 34 60 2 C4 C4 234