Double-ridged Horn Antenna Research Articles

A 10–100-GHz Double-Ridged Horn Antenna and Coax Launcher

The design, fabrication, and measurement of a coax to double-ridged waveguide launcher and horn antenna is presented. The novel launcher design employs two symmetric field probes across the ridge gap to minimize spreading inductance in the transition, and achieves better than 15 dB return loss over a 10:1 bandwidth. The aperture-matched horn uses a half-cosine transition into a linear taper for the outer waveguide dimensions and ridge width, and a power-law scaled gap to realize monotonically varying cutoff frequencies, thus avoiding the appearance of trapped mode resonances. It achieves a nearly constant beamwidth in both E- and H-planes for an overall directivity of about 16.5 dB from 10–100 GHz.

Design and performance analysis of the miniaturised water‐filled double‐ridged horn antenna for active microwave imaging applications

The design and analysis of a miniaturised double-ridged horn antenna for active microwave imaging application are presented in this study. For such an application, a physically small horn is required. For effective signal penetration, a low frequency of operation (about 1.4 GHz) is selected. An array of these sensors is intended for use in a cylindrical breast imaging system, which is under development in the authors laboratory. The miniaturisation is achieved by loading the double-ridged horn antenna with distilled water (e r = 76), a high permittivity, but easily available material. Further size reduction is achieved by reducing the aperture size and flare length in the horn section. The frequency response and both near- and far-field patterns were studied. Two simplified prototypes were fabricated, and as per the system requirements, tested in a cylindrical container filled with distilled water. Measured and simulated reflection and transmission responses are discussed. Measured radiation patterns are compared with the simulated ones to validate the analysis.

A Novel 2–18-GHz Double-Ridged Horn Antenna with an Improved Feed Section Design

In this article, a 2–18-GHz double-ridged horn antenna is designed, and the effects of the E-plane sidewalls on antenna performance are examined. The modifications implemented in the shape of the ridges cause a better voltage standing wave ratio over the whole frequency band. The double-ridged horn antenna is designed to have fewer parts that reduce the possibility of performance reduction due to the production process. The antenna is modeled using commercial 3D electromagnetic simulation software, CST Microwave Studio (Computer Simulation Technology, Germany). After the simulations, a prototype of the designed model is manufactured and tested. The measurement results are in good agreement with the simulation results. The results show that the antenna has low side-lobe levels with a voltage standing wave ratio less than 1.85 (typically 1.5) over the entire frequency band. The method outlined in this article can be used to design a double-ridged horn antenna as a test antenna in electromagnetic compatibility (EMC) applications.

Microwave radiation imaging using inverse synthetic aperture radar technique

Double-ridged horn antennas were used in ultra wideband radar system to create microwave radiation images. The images were obtained using inverse synthetic aperture radar technique. Transfer function of the calibrated radar system was close to one up to 22 GHz. High quality images of metallic and organic objects were created due to unique characteristic of ultra wideband radiated pulse. Metallic objects covered by visually opaque obstacles became detectable. The components of measurement set-up and the data processing are both important for the formation of these images. The obtained results confirmed the ability of ultra wideband radar to form images for various practical applications including security systems. Higher frequency of such radar system can be raised up to 40 GHz-50 GHz.DOI: http://dx.doi.org/10.5755/j01.eee.21.1.5389

A Directional Antenna in a Matching Liquid for Microwave Radar Imaging

The detailed design equations and antenna parameters for a directional antenna for breast imaging are presented in this paper. The antenna was designed so that it could be immersed in canola oil to achieve efficient coupling of the electromagnetic energy to the breast tissue. Ridges were used in the horn antenna to increase the operating bandwidth. The antenna has an exponentially tapered section for impedance matching. The double-ridged horn antenna has a wideband performance from 1.5 GHz to 5 GHz (3.75 GHz or 110% of impedance bandwidth), which is suitable for breast microwave radar imaging. The fabricated antenna was tested and compared with simulated results, and similar bandwidths were obtained. Experiments were conducted on breast phantoms using these antennas, to detect a simulated breast lesion. The reconstructed image from the experiments shows distinguishable tumor responses indicating promising results for successful breast cancer detection.

Dielectric loaded TEM horn-fed ridged horn antenna designfor ultrawideband ground-penetrating impulse radar

A modified double-ridged horn structure is proposed to obtain ultrawideband antenna characteristics over a bandwidth ratio of greater than 40:1 for impulse radar systems. The Vivaldi-shaped TEM horn feeder has been designed to extend the lower cut-off frequency and the partial dielectric loading technique using a small lens inward while the aperture has been implemented to enhance the gain of the standard double-ridged horn antenna without changing the physical dimensions. The starting frequency of the antenna operation band is lowered from 800 MHz to 400 MHz. Moreover, approximately 5 dB gain increment level is achieved from 4 to 10 GHz. It is shown that proper combination of the partial dielectric loaded TEM and ridged horn antennas can be suitable for multiband ground-penetrating radar operations that provide high resolution imaging at different depths. The antenna gain and input reflection performance measurements are presented with comparisons in both the frequency and time domains.

Measurement and evaluation of radar cross section for furniture in an indoor propagation channel

Abstract. This paper has attempted to evaluate the radar cross section (RCS) of two furniture items in an indoor environment in a frequency range of 3–7 GHz of the ultra-wideband (UWB) range. The RCS evaluation is achieved through an extended version of the radar equation that incorporates the channel transfer function of scattering. The time-gating method was applied to remove the multipath effect, a phenomenon which typically occurs in the indoor environment. Two double-ridged waveguide horn antennas for both vertical and horizontal polarizations were used to obtain the transfer function of scattering of the furniture prior to analysis in order to derive their bistatic RCS. The RCS results validate the applicability of the proposed extended radar equation to the indoor propagation prediction.

Design of a Wide-Band Double-Ridged Standard Horn Antenna

This paper will present a novel wide-band double-ridged standard horn antenna at 0.5~6GHz with the software named Ansoft HFSS, which is mainly used for far-field antenna measurement system. A simulation model of wide-band double-ridged horn antenna and the detailed design of each part of the structure will be given. With optimization in HFSS, the results show that the VSWR in the whole frequency band is below 2.4 and average gain larger than 6 dB. Finally, results of the measurement for VSWR, gain and radiation pattern are presented and discussed, which indicates that the built prototype is consistent with the design goals very well.

Experimental Investigation of Factorization Method as a Qualitative Approach for Near-Field Microwave Imaging

In this letter, the Kirsch's factorization image reconstruction method is validated using an experimental setup for scattered field measurement. In this setup, two standard double-ridged horn antennas working in frequency range of 1-18 GHz, one as a transmitter and the other as a receiver, are used inside an anechoic chamber to collect multistatic scattered fields of a hard target. The transmitter is farther from the target than the receiver. While the transmitter is fixed, the target and receiver are rotated on a turntable. Equivalently, the transmitter and the receiver are evenly rotated on the circular arcs with different radii about a fixed target. The antennas are facing each other so that the receiver does not shadow the target. The hard target is an elongated cylinder with a plus-shape cross section of side 12 cm. Successful imaging shows the validity of the measured multistatic data and the inversion method.

DESIGN OF A NOVEL BROADBAND EMC DOUBLE RIDGED GUIDE HORN ANTENNA

An improved double ridged horn antenna (DRHA) is proposed in this paper. By adding the dielectric lens at the aperture of the horn, radiation pattern distortion arising in the high frequency band of conventional DRHA is improved, which leads to higher radiation gain. Meanwhile, ridge slot loading contributes to better impedance matching characteristic, broadening the impedance bandwidth e-ciently. The improved antenna is fabricated and measured, with the measured results consist with the simulation perfectly, which proved the viability of the improvement.

다중모드 회로망 분석을 이용한 광대역 혼 안테나의 효율적인 설계

This paper proposes the effective design procedure for a broadband, double-ridged horn antenna for evaluating the performance of the RF energy harvesting system with a multi-band rectenna. Using multi-mode network analysis, the higher-mode scattering parameters of the transition and horn were acquired and applied to the antenna design, respectively. As a result, the computing time could be reduced and the calculated VSWR(voltage standing wave ratio) of the antenna was very similar to the analyzed result using fully electromagnetic simulation. And there was also good agreement between the simulated and measured results. The designed broadband antenna has a bandwidth of 660~6360 MHz and 6~13.7 dBi peak radiation gain.

An Improved Design for a 1–18 GHz Double-Ridged Guide Horn Antenna

It is a well known fact that the traditional 1-18 GHz double ridge guide horn (DRGH) antenna suffers from pattern deterioration above 12 GHz. At these frequencies, instead of maintaining a single main lobe radiation pattern, the pattern splits up into four lobes. It was shown in the literature that higher order modes are causing the pattern breakup. A benchmark study is performed to establish the performance of typical current and historic 1-18 GHz DRGH antennas. The performance of the antennas are evaluated in terms of gain, VSWR and radiation patterns. An improved 1-18 GHz DRGH antenna is presented. The new design has better gain and VSWR performance without any pattern deterioration. It also consists of significantly fewer parts, reducing the possibility of performance deterioration due to gaps between parts. Two prototypes of the new design were manufactured and tested with excellent agreement between measured and simulated results. The aperture dimensions of the new design are identical to that of the traditional DRGH, making it the only 1-18 GHz DRGH without pattern breakup whose aperture dimensions comply with the requirements specified in MIL-STD-461F - 24.2 by 13.6 cm.

A New Expression of Near-Field Gain Correction Using Photonic Sensor and Planar Near-Field Measurements

We propose a new expression of the near-field gain correction to calculate the on-axis far-field gain from the onaxis near-field gain for a directive antenna. The new expression is represented by transversal vectorial transmitting characteristics of two antennas that are measured by planar near-field equipment. Due to the advantages of the photonic sensor, the utilization of the new expression realizes the measurements of the on-axis far-field gains for two kinds of double ridged waveguide horn antennas within 0.1 dB deviation from 1 GHz to 6 GHz without calibrating the photonic sensor system.

Partially Dielectric-Loaded Ridged Horn Antenna Design for Ultrawideband Gain and Radiation Performance Enhancement

In this letter, a partially dielectric-loaded double-ridged horn antenna (PD-DRHA) that operates at 1-18-GHz frequency band is proposed for ultrawideband applications. The partially dielectric loading technique using a small lens inward the aperture has been implemented to enhance the gain of the standard double-ridged horn antenna (DRHA), without changing the physical dimensions. Approximately 5 dB gain increment level is achieved from 5 to 15 GHz with slight changes on return loss characteristics. Moreover, the pattern distortion of DRHA typically between 12-18-GHz band is improved. The antenna gain, radiation pattern, and input reflection performance measurements are presented with comparisons.

A Large Aperture UWB Antenna Array for Real Beam Radar Imaging

The development of four-element ultra-wideband (UWB) comb taper slot antenna array with 18 cm element spacing for real beam radar imaging is described. The four-element UWB array system with optimum element spacing is analyzed by energy pattern. A wideband double ridge horn antenna is used as the transmitting antenna, the developed large aperture UWB array is used as the receiving antenna. The transmitting antenna and the receiving antenna are combined with impulse time domain measurement system to achieve real beam radar imaging. The receiving impulse signals at various positions are processed by the time delay and sum algorithm. The examples of several aluminum cans have been verified in the resolution and compared with using the UWB array as a receive antenna and the double ridge horn as a transmit antenna in the test setup. The crossrange resolution of UWB antenna array is better than wideband double ridge horn antenna because the beam width of UWB array is narrower.

Design of conical DRH antennas for K and Ka frequency bands

Two conical double-ridged horn (DRH) antennas for K and Ka frequency bands are presented. Detailed simulation and experimental investigations are conducted to understand their behaviors and optimize for broadband operation. The designed antennas were fabricated with 0.01 mm accuracy and satisfactory agreement of computer simulations and experimental results was obtained. The designed conical DRH antennas have voltage standing wave ratio (VSWR) less than 2.1 and 2.2 for the frequency ranges of 18–26.5 GHz (K band) and 26.5–40 GHz (Ka band), respectively. Meanwhile, the proposed antennas exhibit low cross-polarization, low sidelobe level, and simultaneously achieve slant polarization as well as symmetrical radiation patterns in the entire operating bandwidth. An exponential impedance tapering is used at the flare section of the horns. Moreover, a new cavity back with a conical structure is used to improve the VSWR. Numerous simulations via Ansoft HFSS and CST Microwave Studio CAD tools have been made to optimize the VSWR performance of the designed antennas. Simulation results show that the VSWR of the proposed antennas is sensitive to the probe spacing from the ridge edge and the cavity back structure. The designed conical DRH antennas are most suitable as a feed for the reflectors of radar systems and satellite applications. Results for VSWR, far-field E-plane and H-plane radiation patterns, and gain of the designed antennas are presented and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.

Design and experiment of a conical double-ridged horn antenna for 6-18 GHz

A broadband conical double-ridged horn (DRH) antenna with symmetrical radiation patterns, low side lobe level, and low cross polarization is presented. Experimental investigations and detailed simulations are conducted to understand its behavior and to optimize for broadband operation. Good agreement between the measurement and simulation has been achieved. The designed conical DRH antenna introduces a low voltage standing wave ratio (VSWR), which is lower than 2.3 for the frequency range of 6–18 GHz and simultaneously achieves slant polarization as well as stable far-field radiation characteristics in the entire operating bandwidth. The common impedance exponential tapering is used at the flare section of the horn. Moreover, a new cavity back with a conical structure is used to improve the VSWR. The simulated and measured results for VSWR, far field E-plane and H-plane radiation patterns, and gain of the designed antenna are presented and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.

옵셋 파라볼라 안테나를 이용한 1 GHz 이상에서의 전자파 적합성 평가

국제적으로 전자파 적합성에 대한 규제 주파수가 보다 높은 주파수로 상향 조정되어 1 GHz 이상의 주파수로 확장되고 있다. 1 GHz 이상에서의 복사 방출 특성은 기존의 1 GHz 이하의 주파수에 비해 전계 강도가 낮고, 복사 패턴이 날카롭고 경사지는 등 매우 다른 복사 특성을 가진다. 본 논문에서는 이중 쇄기형 혼 안테나를 급전기로 사용하는 옵셋 파라볼라 안테나 시스템을 사용하여 1 GHz 이상의 주파수 대역에서 보다 효과적인 측정이 가능함을 확인하였다. 먼저 옵셋 파라볼라 안테나 시스템의 안테나 인자와 전기장 균일도를 계산할 수 있는 간단한 모델을 제시하였으며, 나아가서 표준 노이즈 소스와 제안된 안테나 시스템을 이용하여 1 GHz 이상의 주파수에서 실제적인 복사 방출 및 복사 내성을 평가하였다. 이러한 실험을 통해서 제안된 안테나 시스템이 기존에 널리 사용되고 있는 이중 쇄기형 혼 안테나에 비해 보다 높은 이득과 전력 효율, 그리고 보다 넓은 전기장 균일도를 가지며, 따라서 1 GHz 이상의 전자파 적합성 평가에 효과적으로 이용될 수 있음을 확인하였다. The upper frequency of international EMC regulations is being expanded above 1 GHz. Radiated emissions above 1 GHz are different from those below 1 GHz that is existing upper regulation frequency, and which have lower field strength and sharper and tilted beam-width, relatively. In this paper, an effective evaluation method to be used above 1 GHz is studied using an offset parabola antenna system having a double-ridged horn antenna as a feed. First, simple model is proposed for calculating antenna factor and field uniformity of the parabola antenna system, and then real radiated emission and radiated susceptibility measurements are performed using a constant noise emitter and the suggested antenna system. The results show that the proposed antenna system has higher gain and power efficiency, and wider field uniformity relative to a conventional double-ridged horn antenna. Therefore, it is confirmed that the proposed system can be effectively used for EMC measurements above 1 GHz.

Ultrawideband Antennas for Magnetic Resonance Imaging Navigator Techniques

Due to its high appreciation for medical diagnostics worldwide, recent developments in magnetic resonance imaging (MRI) aim at adding the capability of creating focused images of moving objects. Among the potential navigator techniques required for such an improved MRI is ultrawideband (UWB) radar. We have studied the performance of UWB antennas for biomedical imaging inside the 3-Tesla MRI system at PTB Berlin. The strong static and time variant magnetic fields give rise to severe mechanical and electrical interactions due to the induced electromagnetic forces. On the other side, the high magnetic field homogeneity required for MR scans can also be affected adversely by the presence of the UWB antennas. The requirements resulting for the design of MRI compatible antennas have been identified and implemented in terms of a novel type of double-ridged horn antennas. We describe the general design strategy and the successful experimental verification of the antenna concept as well as biomedical results achieved with a combination of both UWB and MRI systems.

Design of a Compact Broadband Double-Ridged Horn Antenna

A novel compact broadband double-ridged horn antenna is proposed, which is used in see-through-wall radar system. To cover the low frequency band with relatively small size, the ridge is specially designed to form an irregular cavity. The profile function of the ridges is optimized to realize compact size and wide working frequency band. The irregular cavity increases cavity length to improve the working performance of low frequency. Proposed antenna occupies just half of the length of conventional horn antenna with the same frequency band. Antenna prototype is fabricated and tested, which proves its performance. The VSWR in the whole frequency band from 800 MHz to 6 GHz is below 2.5 with average gain larger than 8 dBi. Reduction in the size of the antenna reduces the weight and cost, which is its advantage.