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In this paper, a broadband dipole antenna with filtering function is proposed. The proposed antenna as a whole comprises a reflector, coaxial cables, a main radiator, and a cross‐center structure. First, two orthogonal dipoles are used as the main radiator and form dual‐polarization. By adding Y‐shaped branches and a cross‐center structure, the base station antenna realizes the filtering function and expands bandwidth. The antenna has filtering function on both sides of the operating frequency band, and the out‐of‐band radiation suppression can be 16 dB at the upper band. The radiation null can be controlled independently by the additional structure. And the parasitic structure has little effect on the realized gain in the operating frequency band. The measurement results show that the relative operating bandwidth of the proposed antenna exceeds 54%, and the isolation between ports is greater than 27 dB. In the operating frequency band, the realized gain is relatively flat, and the HPBW is in the range of 67.3° ± 2.6°. [ABSTRACT FROM AUTHOR]

In this article, a simple coaxial‐feed filtering patch antenna based on stub‐loaded resonator is investigated and analyzed. Owning to the addition of a pair of parasitic stubs, the original rectangular patch antenna acquires a new resonance point and an out‐side radiation null beyond the upper band edge. Then, by establishing a transverse path (introducing connected stubs), the radiating and filtering responses at lower band have been enhanced accordingly. In short, it operates like a three‐order filter with two‐constrained radiation nulls along the passband outside. The novel design has been verified by machining and testing, which meets the expected lately. A fractional bandwidth of 28% and a stable realized gain of 5.8 dBi in‐band are finally measured, and more it also reaches a higher radiation efficiency of 83%. Besides, it exhibits a unidirectional radiation pattern with a low‐cross polarization less than −20 dB in the boresight direction. [ABSTRACT FROM AUTHOR]

A front‐to‐back pattern‐reconfigurable circularly polarized (CP) antenna based on two pairs of planar complementary dipoles with back‐to‐back configuration is presented and implemented. The 8 p‐i‐n diodes are employed into the front and back printed dipole arms. The beam direction can be switched from front‐to‐back, and the left‐right circular polarization can also be changed at each beam direction individually, in which switches are controlled by the dc bias voltage loaded on both ends of the p‐i‐n diode. A prototype operating at 5.8 GHz is then fabricated and measured. Experimental results show that the overlapped bandwidth for 10‐dB return loss and 3‐dB axial ratio of the proposed antenna are from 5.75 to 5.88 (front) and 5.74 to 5.90 GHz (back) for the two pattern states. The presented antenna can be a well choice for ISM systems, which are widely applied in handheld medical terminal and signal detection system. [ABSTRACT FROM AUTHOR]

A novel umbrella‐shaped wideband circular polarization (CP) antenna with a wide half‐power beamwidth (HPBW) and a wide axial ratio (AR) bandwidth is proposed in this article. Two pairs of symmetrical patch dipoles are attached to the surface of an umbrella‐shaped substrate to broaden both the impedance bandwidth (IBW) and the HPBW. A parasitic metallic ring is located immediately above the umbrella substrate to provide further enhancement of the HPBW. Each patch dipole is excited via a coaxial line, while a conductor balun with length of λ0/4 (where λ0 is the wavelength of the center frequency) is introduced to obtain a feeding balance. Measurement results indicate that the proposed antenna has a −10 dB IBW of 71.3% (from 1.03 to 2.17 GHz), and a 3 dB AR bandwidth of 55.6% (from 1.13 to 2.0 GHz). Additionally, an HPBW of more than 110° is obtained over the whole CP bandwidth, 48.2% of which has an HPBW of more than 120°. The antenna has dimensions of 100 × 100 × 28 mm3, which corresponds to (0.52 × 0.52 × 0.14)λ03. [ABSTRACT FROM AUTHOR]

In this paper, the behavior of radiation and coupling reduction between two groove-backed antennas is investigated. An electric line current is placed inside a rectangular groove in a perfectly conducting plane. Fourier transform and series techniques are employed to express the scattered field. Boundary conditions are enforced to obtain simultaneous equations for the discrete modal coefficients, which are then solved in order to calculate the radiated and coupled fields. The behavior of coupling reduction and radiation is discussed in terms of the antenna geometries. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 285–289, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10743 [ABSTRACT FROM AUTHOR]

In this paper, an X‐band dual‐band dual‐polarized medium‐gain antenna (MGA) is designed for deep‐space satellite applications. The MGA has isoflux radiation patterns in the 7.145–7.19 and 8.40–8.45 GHz frequency bands. The concentric ring horn qualification model named MGA is developed for TIAN WEN‐2 (TW‐2) mission. MGA is fabricated and the measurements are conducted on it and its installation on the deck of the TW‐2 Radiation Mockup (RM). The performance evaluation of MGA and its corresponding RM measurements indicate an axial ratio lower than 4.0 dB and a gain higher than 5.8 dBic on the operational bandwidth at the coverage limit of 40° for all azimuth angles (φ). The calculated and measured data align exceedingly well, confirming that MGA satisfactorily meets the requirements for the forthcoming TW‐2 deep‐space spacecraft. [ABSTRACT FROM AUTHOR]

This article proposes a dual‐element antenna working in the 2.4/5‐GHz WLAN bands with high isolation. The antenna element is a coupled‐fed structure, which is formed by a driven monopole and a shorting branch. The decoupling structure disposed between the elements is a hybrid structure, which includes a protruded ground for the 2.4‐GHz WLAN band and a narrow slot etched on the ground plane for the 5‐GHz WLAN band. Moreover, to reduce the dimension of the protruded ground, two 8.2‐nH lumped inductors are embedded in the branches. The measured −10 dB reflection coefficient bandwidths are in the range of 2400‐2497 MHz and 5150‐5940 MHz. The measured transmission coefficient indicates that a good isolation higher than 20 dB over the two bands is obtained. [ABSTRACT FROM AUTHOR]

In this letter, a filter antenna based on novel wide stop-band low-pass filter has been presented. The introduction of mushroom cell makes smaller structure and wider stop-band of the antenna. The filter antenna works in the frequency from 1.8 to 2 GHz (10.5%), and exhibits a good out-band rejection characteristic that the maximum frequency of the stop band is 13 GHz, which is 6.8 times of the central frequency. The measured results show a good agreement with simulated results. [ABSTRACT FROM AUTHOR]