feng Yu

A Simple Compact Reconfigurable Slot Antenna With a Very Wide Tuning Range

A simple and compact slot antenna with a very wide tuning range is proposed. A 25 mm (roughly equal to λH/8, where λH corresponds to the highest frequency of the tuning range) open slot is etched at the edge of the ground. To achieve the tunability, only two lumped elements, namely, a PIN diode and a varactor diode are used in the structure. By switching the PIN diode placed at the open end of the slot, the slot antenna can resonate as a standard slot (when the switch is on) or a half slot (when the switch is off). Continuous tuning over a wide frequency range in those two modes can be achieved by adjusting the reverse bias (giving different capacitances) of the varactor diode loaded in the slot. Through optimal design, the tuning bands of the two modes are stitched together to form a very wide tuning range. The fabricated prototype has a tuning frequency range from 0.42 GHz to 1.48 GHz with Sll better than -10 dB, giving a frequency ratio (fR = fu/fL) of 3.52:1. The measured full spherical radiation patterns show consistent radiation characteristics of the proposed antenna within the whole tuning range.

An Electrically Small Frequency Reconfigurable Antenna With a Wide Tuning Range

An electrically small frequency-reconfigurable antenna with a very wide tuning band is proposed. Three varactor diodes are used to achieve the tunable capacitance. With a modifled feeding structure, the measured tuning range of the fabricated antenna reaches from 457.5 to 894.5 MHz, and the tuning band enhancement is also explained through an equivalent circuit analysis.

Compact Omnidirectional Antenna of Circular Polarization

A compact omnidirectional antenna of circular polarization (CP) is presented for 2.4-GHz WLAN access-point applications. The antenna consists of four bended monopoles, which are simultaneously excited through an associated feeding network. The radiated horizontal and vertical field components are derived based on an analytical model, and the 90^° phase difference between them is shown to be naturally guaranteed. With a size of 0.22λ₀ × 0.22λ₀ × 0.076λ₀, the antenna exhibits a bandwidth (|<i>S</i>₁₁| ≤ -10 dB and AR ≤ 3 dB) of 3.56% and a left-handed CP average gain of 1.39 dB in the azimuth plane at 2.44 GHz.

Full-duplex DOCSIS/WirelessDOCSIS fiber-radio network employing packaged AFPM-based base-stations

The simultaneous wireline (600 MHz) and wireless (5.5 GHz) transmission of data over cable service interface specification (DOCSIS) signals in a hybrid fiber-radio access network is presented. The DOCSIS signal wireless replica is generated by means of an optical harmonic up-conversion technique based on a dual-drive Mach-Zehnder modulator. The optical signal is fed to a base station (BS) where a packaged asymmetric Fabry-Pe/spl acute/rot modulator/detector acts simultaneously as a photodetector and an optical modulator. At the BS, the DOCSIS signals can be fed either to a wireline or a wireless access network, in a highly flexible approach. Full-duplex operation has been demonstrated for both access types, including indoor wireless transmission.

Capacitively Loaded, Inductively Coupled Fed Loop Antenna With an Omnidirectional Radiation Pattern for UHF RFID Tags

A capacitively loaded, inductively coupled fed loop antenna with an omnidirectional radiation pattern for UHF radio frequency identification (RFID) tags is proposed. The inductively coupled feed structure is beneficial for conjugate impedance matching. The loaded capacitors in the radiating and feeding loops allow for easy control of the resonant frequency and the antenna reactance, respectively. The omnidirectional radiation pattern on the horizontal plane makes the proposed tag insensitive to be mounted on different target objects. With a small size of 43 × 43 mm2, the measured maximum reading range of the prototype is 9.5 m with a total transmitted power of 4.0 W effective isotropic radiated power (EIRP).

Novel Flexible Dual-Frequency Broadside Radiating Rectangular Patch Antennas Based on Complementary Planar ENZ or MNZ Metamaterials

A novel scheme of designing dual-frequency broadside radiating rectangular patch antennas is proposed. Cavity model analysis shows that, by partially loading Lorentzian dispersive epsilon-near-zero (ENZ) or mu-near-zero (MNZ) metamaterials (MTM), the electric fields at two radiating edges of the patch antennas can be out of phase and a broadside radiation pattern can be achieved at both operating frequencies. With proper constitutive parameters and filling ratio, the frequency ratio (FR) of the dual-frequency antenna can be flexibly chosen in a very wide range. Experimental results of a double positive (DPS)-MNZ based dual-frequency patch antenna, with its MNZ practically implemented by a complementary electric-LC (CELC) array etched on the patch surface, demonstrates the validity of such scheme. A detailed design procedure is also described. Compared to some conventional and other MTM based techniques, the proposed dual-frequency solution shows its advantages on excellent broadside radiating pattern with low cross-polarization and reduced back lobe, FR flexibility, and ease of fabrication.

Electrically small omni-directional antenna of circular polarization

A compact omni-directional antenna of circular polarization (CP) is presented for 2.4 GHz WLAN access-point applications. The antenna consists of four bended monopoles and a feeding network simultaneously exciting these four monopoles. The electrical size of the CP antenna is only λ₀/5×λ₀/5×λ₀/13. The impedance bandwidth (|S₁₁|<;-10 dB) is 3.85% (2.392 GHz to 2.486 GHz) and the axial ratio in the azimuth plane is lower than 0.5 dB in the operating band.

High gain conical beam antenna with two concentric coaxial apertures

A high gain conical beam antenna consisting of two concentric open-ended coaxial apertures is proposed in this paper. With a diameter of 2.474λ0, the aperture antenna achieves a conical radiation beam with a gain of 12.1 dB and a maximum beam-pointing angle of θ=18° at 10 GHz. Simulated results are presented and discussed.