Quadrifilar-curl antenna for the "Big-LEO" mobile satellite service system

Colburn, J.S.; Samii, Y. Rahmat

doi:10.1109/aps.1996.549785

Cited by 14 publications

(8 citation statements)

References 2 publications

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“…Let us assume that two antennas are coupled to each other by the coupling coefficient , which means that the transmitted signal from one antenna reaches another antenna with the attenuation by . The -parameters of two antenna ports (ports 5 and 6) are (7) For the balanced directional coupler with mismatched load ( , ) and mutual coupling , the scattering matrix is (8) where From the above equation, the Tx leakage of the balanced coupler with the mutual coupled antenna ports can be expressed as follows:…”

Section: Antenna Mutual Couplingmentioning

confidence: 99%

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RFID Reader Front-End Having Robust Tx Leakage Canceller for Load Variation

Lim

Park

Son

et al. 2009

IEEE Trans. Microwave Theory Techn.

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A novel front-end structure for ultra-high-frequency RF identification reader is proposed. The proposed front-end consists of a balanced coupler and four-port feed antenna system. The proposed balanced coupler structure has high transmit/receiver isolation feature and good insensitivity to load variations. The proposed four-port feed antenna system is applied for removing the coupling among antennas, which deteriorates the isolation. The proposed system is numerically analyzed and verified experimentally as well.

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Section: Antenna Mutual Couplingmentioning

confidence: 99%

“…In addition, the radiation pattern of the antenna should be suitable to achieve the appropriate readable range for a given application. Recently, patch and helix (spiral) antennas are used widely because of their excellent CP and high gain characteristics ( [6], [7]). …”

Section: Introductionmentioning

confidence: 99%

RFID Reader Front-End Having Robust Tx Leakage Canceller for Load Variation

Lim

Park

Son

et al. 2009

IEEE Trans. Microwave Theory Techn.

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“…Spiral antennas are particularly known for their ability to produce a very wideband almost a perfect circularly polarized radiation over their full coverage region [1][2][3][4][5]. As a result of this polarization characteristic and the ability to produce a broad zenith-directed pattern, spiral antennas are popular for their use in satellite mobile communication handsets [2,6,7].…”

Section: Introductionmentioning

confidence: 99%

Design of dual‐band quadrifilar spiral antennas for satellite‐mobile handsets

Abd‐Alhameed

Zhou

See

et al. 2010

Micro & Optical Tech Letters

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larger than the bandwidth of the PDs. The fundamental frequencies used were 10 GHz and 10.1 GHz, and the result of the measurement of the UTC-PD at 40 mA is shown in Figure 3 (right inset). The two tone measurements were repeated for different photocurrents, and the results are presented as the OIP3 versus the photocurrent in Figure 4(a). The OIP3 of the UTC-PD was found to be increasing with bias voltage, and therefore a bias À6 V was chosen, which was found to be the largest safe voltage. The increase of the OIP3 with voltage is consistent with results of [8]. Because of the dynamic range limitations of the ESA, the measurements of PIN-PD and the UTC-PD were limited to photocurrents between 5 and 13 mA, and 15 and 40 mA, respectively. The UTC-PD had about 15-20 dB larger OIP3 in this measurement range. The measurements of the linearity and noise can be added together under the assumption that the photodetector is limiting the link, as mentioned in the introduction, and thus, the SFDR can be calculated and is plotted as a function of photocurrent in Figure 4(b). As a consequence of the high OIP3 of the UTC-PD, the SFDR is more than 10 dB higher than for the PIN-PD.

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“…Many physically less-obtrusive circular polarized antennas have been studied for the handset application [3], [4], but the helix antenna is considered a good candidate element because it can provide wide-band impedance performance with acceptable circular polarization when operated in axial mode. An additional benefit of the helix is that at lower frequencies it can provide linear polarization when operated in normal mode.…”

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confidence: 99%

Human proximity effects on circular polarized handset antennas in personal satellite communications

Colburn

Rahmat‐Samii

1998

IEEE Trans. Antennas Propagat.

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Satellite-based systems are the next step in mobile communications. Recently, several low and medium earth orbit mobile communication satellite systems have been proposed and are currently being deployed. For all these systems, high-performance circularly polarized antennas for the mobile terminals are of importance. Although considerable material is available on circularly polarized antennas, there is an absence of information on how the human's close proximity to the antenna affects the circular polarization purity of the radiated field. This paper presents an analysis of representative circularly polarized helical handset antennas. Although other physically less obtrusive circular polarized antennas are available for the handset, the helix is used because of its wide bandwidth properties and capability to provide both circular and linear polarization. Thus, this element could be used for handsets that are planned to work with both the terrestrial-based communications systems of today and the satellite-based communication systems of tomorrow. The intent is to characterize the effects the close proximity of a human head model has on the computed performance of the circular polarized antenna. The method of moments (MoM) and finitedifference time-domain (FDTD) numerical techniques are used to study various helix structures on top of a small box representing a handset. In order to be able to effectively apply FDTD, a novel square helix structure is introduced. Results computed with these two techniques are compared to illustrate the accuracy of each implementation. The results indicate significant polarization purity degradation caused by the presence of a human head. For the particular geometry simulated, the presence of a head model degraded the average axial ratio within a verticle 50 cone from 2.9 to 9.1 dB. This significant increase in axial ratio can have profound effects on link budgets.

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Quadrifilar-curl antenna for the "Big-LEO" mobile satellite service system

Abstract: @ 7 @ -3 2 1~a l 0 1~l E E E

Cited by 14 publications

References 2 publications

RFID Reader Front-End Having Robust Tx Leakage Canceller for Load Variation

RFID Reader Front-End Having Robust Tx Leakage Canceller for Load Variation

Design of dual‐band quadrifilar spiral antennas for satellite‐mobile handsets

Human proximity effects on circular polarized handset antennas in personal satellite communications

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