Ultrahigh-frequency loop antennas

Alford, Andrew; Kandoian, A.G.

doi:10.1109/ee.1940.6435249

Cited by 46 publications

(20 citation statements)

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“…They always have mushroom patch and can achieve omnidirectional performance. A horizontally polarized component can be obtained by omnidirectional magnetic dipole which can be realized by the arc-shaped dipoles or by an Alford loop antenna and its variants [13][14][15]. In [9], the proposed antenna consists of a top-loaded cylindrical monopole and four printed arc-shaped dipoles to obtain CP wave, and the 90 • phase difference can be achieved by adjusting the diameter of the ground.…”

Section: Introductionmentioning

confidence: 99%

A Novel Single Feed Omnidirectional Circularly Polarized Antenna With Wide Ar Bandwidth

Yang¹,

Liu²,

Zhang³

et al. 2014

PIER C

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A novel omnidirectional circularly polarized (CP) antenna with single feed is proposed for 2.4 GHz WLAN applications. Based on the zeroth-order resonance (ZOR) mode of epsilon negative (ENG) transmission line (TL), the antenna excites uniform vertically polarized E-field just as the monopole does. A modified Alford loop with electromagnetic coupling fed by L-shaped strip consists of four curved branches, which is placed on the top of the antenna and generates an equivalent horizontally polarized magnetic dipole mode. Once the two orthogonally polarized components are equal in amplitude but different in phase by 90 • , omnidirectional CP wave can be obtained. The measured results show that the impedance bandwidth (S 11 < −10 dB) is 6% (2.38-2.53 GHz), and the 3-dB axial ratio bandwidth in the azimuth plane is very wide which achieves 54% (1.60-2.80 GHz). Additionally, the 3-dB axial ratio beamwidth is over 50 • for radiation pattern in elevation plane. Moreover, the antenna achieves excellent omnidirectional right-hand CP performance with a variation of 0.5 dB in the azimuth plane and an average gain over 1.5 dB across the operating band, which are well applied to the wireless system.

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Section: Introductionmentioning

confidence: 99%

A Novel Single Feed Omnidirectional Circularly Polarized Antenna With Wide Ar Bandwidth

Yang¹,

Liu²,

Zhang³

et al. 2014

PIER C

View full text Add to dashboard Cite

show abstract

“…As another type of magnetic dipole, loop antennas have been intensively studied and applied in all kinds of radio systems since the late 1930s . In many classical textbooks, an ideal loop antenna with pure standing‐wave current distribution, horizontally placed in the xy ‐plane only generates E φ component in the far‐field, and the E‐field along the loop's axis is always equal to zero regardless of its varied size .…”

Section: Design Approachesmentioning

confidence: 99%

On the multi‐resonant antennas: Theory, history, and new development

2019

Int J RF Microw Comput Aided Eng

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A survey of multi‐resonant antennas is comprehensively presented, with emphasis on theoretical framework, design approaches, and practical examples. This article begins with a brief history of the multi‐resonant dipole theory, and then concentrates on the design approaches that have been developed to typical, basic antenna elements, for example, electric dipole antenna, slotline antenna, loop antenna, complementary dipole antenna, and microstrip patch antenna. Design examples for different practical applications are then raised. In final, the multi‐resonant antenna design approach is summarized and compared to some relevant antenna design techniques.

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“…Usually, horizontally polarized omnidirectional radiation pattern is generated by exciting an annular current uniformly in horizontal plane, just as electric current loop antennas do. The Alford antenna and its derivatives are the classical HP omnidirectional antennas which have been widely studied . However, this type of antenna is hard to be matched with 50Ω axial cable due to the small input resistance and large reactance.…”

Section: Introductionmentioning

confidence: 99%

Wideband and compact horizontally polarized omnidirectional antenna using composite dipole elements

Yang

Chen

et al. 2016

Int J RF Microw Comput Aided Eng

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A wideband horizontally polarized (HP) omnidirectional antenna is constructed and experimented in this article. The antenna consists of four composite dipoles forming a circular array in the azimuth plane and four pairs of parallel strip lines as impedance transformer networks. Two kinds of dipoles compose the composite dipole to achieve a wideband operation. By utilizing the composite dipole, four resonances can be simultaneously excited and manipulated to increase the bandwidth. A prototype is manufactured to validate the method. The dimensions of the antenna are just 0.62λ0 × 0.62λ0 × 0.03λ0 (λ0 is the free‐space wavelength at center frequency). The measured results show that the presented antenna has a impedance bandwidth of 58.6% (1.63–2.98 GHz) for VSWR ≤2. The gain variations are less than 0.6 dB at the azimuth plane in the operating band. Meanwhile, the cross‐polarization is less than 20 dB and the peak gain reaches 1.7 dBi among in the band. These advantages of the antenna make it suitable for 4G mobile communication applications.

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Ultrahigh-frequency loop antennas

Cited by 46 publications

References 0 publications

A Novel Single Feed Omnidirectional Circularly Polarized Antenna With Wide Ar Bandwidth

A Novel Single Feed Omnidirectional Circularly Polarized Antenna With Wide Ar Bandwidth

On the multi‐resonant antennas: Theory, history, and new development

Wideband and compact horizontally polarized omnidirectional antenna using composite dipole elements

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