• ETRI Journal
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• v.37 no.1
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• pp.26-31
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• 2015

Axial-ratio (AR) bandwidth enhancement is achieved for a circularly polarized (CP) cylindrical dielectric resonator antenna (DRA) using a wideband hybrid coupler (WHC) combined with dual probe feed. The presented WHC, comprised of a Wilkinson power divider and a wideband $90^{\circ}$ shifter, delivers good characteristics in terms of 3 dB power splitting and consistent $90^{\circ}$ (${\pm}5^{\circ}$) phase shifting over a wide bandwidth. In turn, the proposed CP DRA, for the employment of the WHC, in place of conventional designs, provides a significant enhancement on AR bandwidth and impedance matching. The antenna prototype with the WHC exhibits a 3 dB AR bandwidth of 48.66%, an impedance bandwidth of 52.5% for voltage standing wave ratio (VSWR) ${\leq}2$, and a bandwidth of 44.66% for a gain of no less than 3 dBi. Experiments demonstrate that the proposed WHC is suitable for broadband CP DRA design.

• ETRI Journal
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• v.41 no.3
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• pp.289-297
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• 2019

In this paper, a wideband, circularly polarized patch antenna is proposed that leverages the unidirectional resonant modes of a circular patch mounted on top of a grounded dielectric-ferrite substrate. The proposed antenna is fed via the proximity coupling method and several parasitically coupled patches are placed on a dielectric superstrate to enhance the impedance bandwidth of the antenna. The resonant modes of the structure rotate only in the clockwise or counter clockwise directions. In the frequency range where the effective permeability of the ferrite layer is negative, the resonance frequencies of these modes differ significantly, which produces a large axial ratio (AR) bandwidth. For the proposed antenna, the numerical results show the 10 dB impedance bandwidth to be around 44% and the 3 dB axial ratio bandwidth to be higher than 64%.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.3
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• pp.47-52
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• 2012

This paper is in regard to design and experiment about the radar's circular polarization antenna operating in the Ku band. By using the Post to manufacture the circular polarization antenna using the linear antenna, it could reduce the structural size of an antenna. 3 Posts were used in order to broaden the Axial ration Bandwidth of the circular polarization antenna. The distance and length between Posts and Post were appropriately selected for the axial ratio optimization and applied in the design. It was verified that the designed antenna has the impedence bandwidth of 12.7%, axial ratio performance less than 2dB and gain of 7.8dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.393-400
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• 2002

In this paper, a novel series feeding cross-aperture coupled microstrip antenna with the effect of hybrid feeding is proposed and demonstrated experimentally to improve narrow axial ratio bandwidth of cross-aperture coupled antenna with single feeding among the various methods for generating circular polarization. The validity of a proposed series feeding cross-aperture coupled microstrip antenna is shown by comparing experimental results between the reported and the proposed microstrip antenna, and 2${\times}$2 array microstrip antenna based on the proposed single microstrip antenna used sequential rotation technique to accomplish broader axial ratio bandwidth. In the proposed single and 2${\times}$2 array microstrip antenna, the measured axial ratio bandwidths are 110 ㎒(4.6%) and 420 ㎒(17.5%), maximum gains are 8.2 ㏈i and 12.5 ㏈i, 3 dB gain bandwidths are above 400 ㎒(16.7%), and impedance bandwidths for the VSWR<1.5 are 240 ㎒(10%) and 500 ㎒(20.8%), respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.748-754
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• 2000

A novel single feed wide band CP stacked microstrip antenna using crossed slots has been designed, fabricated and measured. For the single rediating element the designed 10dB return loss bandwidth is 34.5%99.45~13.54 GHz), 3dB axial ratio bandwidth is 18.7%(11.17~13.39GHz), and 6 dB gain bandwidth is 29%(10.21~13.64GHz). For the 2$\times$2 array designed using a sequential rotation method, the 10dB return loss bandwidth is 35.9%(9.69~13.94GHz), 3dB axial ratio bandwidth is 34.6GHz (9.93~14.03GHz), and 6dB gain bandwidth is 27.4%(10.35~13.6GHz). For the fabricated 8$\times$8 array antenna, the 10dB return loss bandwidth is 27.3%(10.17~13.41GHz), 3dB axial ratio bandwidth is 27.9GHz(10.1~13.4GHz), and the radiation pattern is good agreement with theory. This antenna can be used for broadband applications for communications or broadcasting in Ku band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.418-422
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• 2003

In this paper a dual-band circularly polarized stacked microstrip antenna for Global Positioning System (GPS) service and Digital Multimedia Broadcasting (DMB) service is designed. By stacking two different corner-truncated square microstrip patches, dual-band, dual polarization characteristic is obtained. Experimental results show impedance bandwidth of 60 MHz (3.8%) and axial ratio bandwidth of 6 MHz (0.4%) in GPS and impedance bandwidth of 126 MHz (4.7%) and axial ratio bandwidth of 30MHz (1.1%) in DMB.

• ETRI Journal
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• v.46 no.3
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• pp.404-412
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• 2024

We propose a method for increasing the bandwidth of a substrate-integrated-waveguide (SIW) cavity-backed antenna with taper-based micro-strip SIW transition feeding. For radio transmission, a circular slot is etched on top of the SIW cavity. For optimal antenna design, the slot is etched slightly away from the cavity center to generate circularly polarized waves. Simulations show a wide axial ratio bandwidth of 7.860% between 11.02 GHz and 11.806 GHz. Experimental results confirm a similar wide axial ratio bandwidth of 4.9% between 10.8 GHz and 11.35 GHz. An SIW feed from an inductive window excites the radiating circular slot, resulting in a simulated wide impedance range of 1.548 GHz (10.338 GHz-11.886 GHz) and bandwidth of 13.93%. Experimental results show a wide impedance of 2.08 GHz (10.2 GHz-12.08 GHz) and bandwidth of 18.84%. The SIW cavity-backed antenna creates a unidirectional pattern, leading to gains of 6.61 dBi and 7.594 dBi in simulations and experiments, respectively. The proposed antenna was fabricated on a Rogers RT/Duroid 5880 substrate, and the reflection coefficient, radiation patterns, and gains were tested and compared using a computer simulator. The developed broadband antenna seems suitable for X-band applications.

• Progress in Superconductivity
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• v.3 no.2
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• pp.178-182
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• 2002

Superconducting four-element patch array antenna was designed and fabricated using $high-T_{c}$ superconducting (HTS) thin film. The array antenna has single-feed circularly polarization and a resonance frequency of 11.85 GHz fur satellite communication system. To fabricate this antenna $YBa_2$$Cu_3$$O_{7-x}$(YBCO) superconducting thin films were deposited using rf-magnetron sputtering technique. Sequential rotation technique based on radiation elements($0^{\circ}$ , $90^{\circ}$, 1$80^{\circ}$, $270^{\circ}$ phase delay) was utilized to achieve circularly polarization. Simulated and measured results, the analysis on resonant frequency(fr), return loss, and bandwidth are presented. The results show that 10 dB return loss bandwidth of the array antenna is 11.04 GHz~12.59 GHz (13.15%) and 3dB axial ratio bandwidth is 11.42~12.52 GHz (9.2%).).).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.998-1009
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• 1999

In this paper, a microstrip aperture-patch antenna and a microstrip ring antenna, which have single microstrip line feeding systems for the circular polarization, are designed, and experimental results are presented at X-band. The microstrip aperture-patch antenna is characterized by its wide operating frequency range, and the microstrip ring antenna is suitable for a basic radiator in the large array antenna due to its small size. Several design parameters for these antennas are considered and analyzed to improve antenna characteristics such as VSWR bandwidth and axial ratio. Initially, the sizes of the aperture and ring radiator are determined on a basis of the cavity model, then shapes of the patch within the aperture and the inner stub of the ring are optimized using Ensemble software. Measurement results show that the aperture-patch antenna has 25% of VSWR bandwidth and 1.2dB of axial ratio at the boresight, and the ring antenna has 6.7% of VSWR bandwidth and 1.6dB of axial ratio at the boresight.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.919-930
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• 2001

This paper presents a wideband technique of impedance and axial-ratio bandwidth which uses the stacked planar array structure through optimum design of sub-polarization generating sections and parasitic patch. So, the effect of the dual-resonance characteristic can contribute to the bandwidth expansion of single fed planar array antenna using circular polarization which doesn\`t hire previous bandwidth expansion technique. The antenna can be used as a dual-band antenna by adjusting the resonance frequencies as well, and then the antenna is designed and fabricated in the frequency band of domestic satellite-TV service. This antenna has the performance of 9.7 % impedance bandwidth and 24 dBi of antenna gain. And it has also 2.8 % and 1.4 % of 3 dB Axial-ratio bandwidth at 11.4 GHz and 11.8 GHz respectively.