Bow-tie Slot Antenna Research Articles

Diced and grounded broadband bow‐tie antenna with tuning stub for resonant tunnelling diode terahertz oscillators

Radiation from antennas integrated with indium phosphide (InP)-based resonant tunnelling diode (RTD) oscillators is mainly through the substrate because of the effects of the large dielectric constant. Therefore, hemispherical lenses are used to extract the signal from the backside of the substrate. In this study the authors present a broadband bow-tie slot antenna with a tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to the air-side direction. Antenna integration with RTD oscillators is described in this study as well. Two-port bow-tie slot antennas were designed and characterised and showed the suitability of integration with power combining RTD oscillator circuits which are based on mutual coupling. The antennas were fabricated using electron beam lithography on a semi-insulating InP substrate. Simulated and measured bandwidth almost extends the entire frequency range 230–325 GHz. Simulations shows air-side radiation pattern and antenna gain of around 11 dB at 280 GHz. Simulations also show that the antenna may be fed with a 50-Ω or 30-Ω feed line, i.e. suitable feed lines, without compromising its performance which may prove beneficial for optimum loading of RTD oscillators.

Wireless Communication in Feedback-Assisted Active Sensors

A novel wireless high-resolution resonant-based microwave sensor is presented for chemical sensing applications. A combination of antenna with a planar microstrip resonator increases the flexibility, durability, and reliability while extending the application of the sensor to areas with limited access and harsh environments. The main core of this sensor is a passive planar resonator, which operates at 1.41 GHz and is reinforced by a regenerative active feedback circuitry. The regenerative active feedback loop compensates the power loss of the sensor and, as a result, provides an extremely high-quality factors. Four bow-tie slot antennas of the moderate gain of 5 dB, linearly polarized over the frequency span of 1.35–2 GHz is used to communicate in short range. The sensor model is implemented using the finite-element method and a complete set of simulation is presented. The simulation results are confirmed by the measurements for resonant profile variation in material sensing. The initial quality factor of the fabricated sensor, considering the antennas and resonator loss is Q $\approx $ 22000, which broadens the range of sensing platforms into classification of low concentrated (0.003125–0.1 g/mL) salt water as well as material detection of common chemicals such as IPA, acetone, ethanol, methanol, and water.

A 100–300-GHz Free-Space Scalar Network Analyzer Using Compact Tx and Rx Modules

This paper presents a 100–300-GHz quasi-optical network analyzer using compact transmitter and receiver modules. The transmitter includes a wideband double bow-tie slot antenna and employs a Schottky diode as a frequency harmonic multiplier. The receiver includes a similar antenna, a Schottky diode used as a subharmonic mixer, and an LO/IF diplexer. The 100–300-GHz RF signals are the 5th–11th harmonics generated by the frequency multiplier when an 18–27-GHz LO signal is applied. The measured transmitter conversion gain with $P_{\textrm {in}} = 18$ dBm is from −35 to −59 dB for the 5th–11th harmonic, respectively, and results in a transmitter EIRP from +3 to −20 dBm up to 300 GHz. The measured mixer conversion gain is from −30 to −47 dB at the 5th–11th harmonic, respectively. The system has a dynamic range > 60 dB at 200 GHz in a 100-Hz bandwidth for a transmit and receive system based on 12-mm lenses and spaced 60 cm from each other. Frequency-selective surfaces at 150 and 200 GHz are tested by the proposed design and their measured results agree with simulations. Application areas are low-cost scalar network analyzers for wideband quasi-optical 100 GHz–1 THz measurements.

Double Bow-Tie Slot Antennas for Wideband Millimeter-Wave and Terahertz Applications

This paper presents millimeter-wave and terahertz double bow-tie slot antennas on a synthesized elliptical silicon lens. Two different antennas are designed to cover 0.1–0.3 and 0.2–0.6 THz, respectively. The double bow-tie slot antenna results in a wide impedance bandwidth and 78–97% Gaussian coupling efficiency over a 3:1 frequency range. A wideband coplanar-waveguide low-pass filter is designed using slow-wave techniques, and the measured filter response shows an S $_{21}$ < −25 dB over a 3:1 frequency range. Absolute gain measurements done at 100–300 GHz and 200–600 GHz confirm the wideband operation of this design. The double bow-tie slot antenna is intended to fill the gap between standard double-slot antennas and log periodic and sinuous antennas, with applications areas in radio astronomy and imaging systems.

Novel Miniaturized Antenna Designs for In-traffic Air-coupled Ground Penetrating Radar Systems

Ground penetrating radar (GPR) antennas are key elements for the operation of air-coupled, compact, low-cost systems that can be operated at road speeds to map subsurface defects such as corroded rebar, trapped moisture, voids, and pavement layers. This paper presents requirements and tradeoffs for such antennas, as well as a brief methodology for the design process to frame the context and boundary conditions of the antenna problem. Furthermore, the paper discusses a number of planar antennas that have been designed in printed circuit board (PCB) technology using low-cost, glass-reinforced epoxy laminate sheets such as FR4.The ultra-wide-band operation of antennas, along with other key parameters such as gain and beam width, is very important in the design of a useful GPR antenna for air-coupled operation. The interconnected relationship between antenna parameters limits the designs and constrains the upper bounds of the performance that can be achieved. Regulatory specifications such as FCC compliance create additional burden on the specifications and requirements.A rounded bowtie antenna, a slotted bowtie antenna and two types of Vivaldi antenna are designed, simulated, fabricated, and characterized. All are intended to operate within the 1.1–3.5 GHz frequency band and benefit from compact size while providing high gain to allow for the detection of pavement layers and rebar in bridge decks to a depth of up to 2 feet. In-field measurements of the antennas, together with the GPR system, are presented for static testing scenarios such as buried rebar in a sand box and concrete slab. The antenna testing over the sandbox and concrete slab demonstrates the great potential of utilizing the proposed antennas in air-coupled GPR systems, especially the compact rounded bowtie and slotted bowtie antennas.

Study and Design of Broadband Bow-tie Slot Antenna Fed With Asymmetric CPW

In this communication, a new style of broadband bow-tie slot antenna with an improved gain is presented. It is fed by an asymmetric coplanar waveguide (ACPW) with different slot lengths. By adjusting the length of one ACPW slot, the impedance characteristic of the antenna is greatly improved so that the bandwidth is broadened. Meanwhile, to improve the gain at low frequency band, a loop strip is added in the bow-tie slot. The simulated and measured results show that the proposed antenna can operate from 2.76 GHz to 8.1 GHz and the relative bandwidth is 100.4%. Furthermore, the flatter gain within the operating frequency band is obtained and the maximum gain at beam peak reaches 5.53 dBi.

Multibroadband Slotted Bow-Tie Monopole Antenna

In this letter, a coplanar waveguide (CPW)-fed multiband bow-tie monopole antenna is proposed. This antenna can be easily designed to meet the requirement of multiple operating frequencies by using the proposed approach. Multiple bent monopoles, which correspond to different operating frequencies, are generated by etching slots of different lengths in a bow-tie patch. The length of each bent monopole is determined under the quarter wavelength resonance condition. Each frequency band can be easily satisfied for the broadband character because the bow-tie patch can be treated as a broadband impedance-matching structure. This study demonstrates a triple-band slotted bow-tie monopole antenna for WLAN/WiMAX/LTE applications with bands of 2.4–2.7 GHz, 3.4–3.7 GHz, and 5.2–5.8 GHz. The size of the proposed antenna fabricated on a 0.8 mm-thick FR4 substrate with a dielectric constant of 4.2 without considering the ground plane size is only $19.5 \times 9.0~\hbox{mm}^{2}$ . The good agreement between the simulation results and the measurement validates the proposed design approach.

A COMPACT MULTIBAND BOW-TIE DIPOLE SLOT ANTENNA FOR WLAN AND WIMAX APPLICATIONS

A compact multiband bow-tie dipole slot antenna fed by coplanar waveguide (CPW) is proposed in this paper. Multiple resonant mode technique and notch-band technique have been combined in this design to form triple-band operation just by adding single elements. Based on this, a pair of hairpin-shaped branches is implemented on each arm of the bow-tie slot antenna. A notch- band property is achieved compared with the original wideband bow-tie antenna (without branches). Meanwhile, a new lower resonant frequency is obtained by using this kind of structure, which means that the size is compact in nature, and the triple-band operation is achieved. The notch-band and lower resonant frequency can be tuned by changing the length of the branch. The parameters of the antenna, including reflection coefficients, current distributions, radiation patterns and gain, are achieved by numerical simulations and measurements. The results indicate that the slot size of the proposed antenna is 52. 4m m× 22.3 mm, and the proposed antenna can offer triple-band operation at 2.39-2.50 GHz (4.5%), 3.38-3.79 GHz (11.4%) and 4.87-6.23 GHz (24.5%), which is suitable for WLAN in the 2.4/5.2/5.8-GHz band and WiMAX in the 3.5/5.5-GHz bands.

Using polarization diversity in the detection of small discontinuities by an ultra-wide band ground-penetrating radar

A ground-penetrating radar (GPR) has been developed for civil engineering applications. Ultra-wide band (UWB) bowtie slot antennas operating at frequencies from 460MHz to beyond 4GHz have been designed to be integrated in a ground-penetrating radar (GPR) positioned very close to the soil surface. FDTD modeling has allowed to define the optimal geometrical parameters associated with the ground-coupled radar system that has been studied in two polarization configurations TE and TM. The ability of the GPR system in detecting small discontinuities using polarization diversity has been analyzed considering several buried canonical objects with different dielectric characteristics. Measurements in a sand box have been compared to full-wave simulations.

Dual‐band bow‐tie slot antenna fed by coplanar waveguide

A dual-band coplanar waveguide (CPW)-fed bow-tie slot antenna is proposed, which consists of a bow-tie slot, a pair of sector parasitic patches and a modified grounded plane with a band-notch property. The impedance matching, the resonant mode, the radiation patterns and the current distributions are studied. To generate dual-band characteristics, a V-shaped slot is etched on the radiating ground. Experimental and simulated results demonstrate that the antenna exhibits two separate impedance bandwidths of 1450 MHz (about 32.8% centred at 4.43 GHz) and 3500 MHz (about 37.8% centred at 9.25 GHz), which satisfy aircraft radar and X-band applications.

Dual‐band slot‐coupled patch antenna with broad bandwidth and high directivity for WLAN access point

A dual-band slot-coupled patch antenna for the external access point of the wireless local area network (WLAN) band is implemented. The antennas consist of two radiators on three layers. The first radiator is a slotted bow-tie antenna operating at the 2.4–2.483 GHz band. The second radiator is a patch antenna with parasitic elements operating at 4.095–5.845 GHz. To enhance the bandwidth, a coupled feeding was used in the first radiator and a parasitic patch was used in the second radiator. To improve the directivity and isolation in both the radiators a parasitic patch and chock were used. The peak gain was more than 6 dBi in the first antenna and more than 8 dBi in the second antenna.

Performance Analysis of Energy Pattern and Power Patterns for UWB Antenna and Narrowband Antenna

Power patterns in the frequency domain are usually used to describe the antenna performance in narrowband communication systems; however, they are not sufficient for ultra wideband (UWB) antennas in wideband communication systems. In this paper, energy pattern and energy gain are introduced to describe the performance of UWB antennas. Numerical simulations and measurements are used to demonstrate the difference between power patterns and energy patterns for narrowband Yagi-Uda antenna, UWB CPW-fed bow-tie slot antenna, and UWB comb taper slot antenna. The results of simulations and measurements are agreement not only in energy pattern, but also in received voltage at various observation angles. For narrowband antennas, the energy patterns are similar to that of the power patterns in the main beam region. However, there are quite differences between power pattern in frequency domain and energy pattern in time domain for UWB antennas.

An array of lens-coupled antennas for cosmic microwave background measurements in the 30 Ghz band

An array of bow-tie slot antennas coupled through an extended hemispherical lens is proposed to operate in the 30 GHz frequency band. The design includes a combination of three microstrip Wilkinson power dividers (WPD) and transitions to coplanar wave guides (CPW) to form the feeding antenna network. This configuration is suitable for the integration with heterodyne imaging detectors commonly used in radioastronomy. Measurements and simulation results exhibit a frequency range of operation from 20 to 40 GHz with a bandwidth of 24% achieved for −10 dB return loss at the central frequency. The measured radiation patterns show a maximum peak gain of around 13 dB with HPBW of 10° for the E-plane, and whose first side lobes are lower than 13 dB below the main lobe in both angular shift sides. The presented results will be considered as preliminary feasibility studies in the 30 GHz QUIJOTE-CMB Instrument, which is designed to study the anisotropies of the Cosmic Microwave Background (CMB).

Coplanar-to-Rectangular Waveguide Transitions Using Slot Antennas

A coplanar-to-rectangular waveguide transition using a dipole slot antenna is proposed in this paper. The advantage of this transition is that no intermediate transition and vias are needed in this direct transition. Parameter studies of this transition demonstrate that a transition having a fractional bandwidth of 22.85%, for which the return loss is larger than 15 dB, is achieved in the X-band (8.2-12.4 GHz). Furthermore, in order to enhance the bandwidth, the dipole slot antenna is replaced by a bowtie slot antenna. This design demonstrates a wider fractional bandwidth of 26.67%. Back-to-back transitions for both designs were fabricated and measured in order to verify these designs, and the measurement results agree well with the simulation results.

Wide band coplanar waveguide-fed bowtie slot antenna for a large range of ground penetrating radar applications

For the non-destructive sounding of the sub-surface for a large range of applications, a coplanar waveguide-fed bowtie slot antenna operating in a wide frequency band [0.4;1.5] GHz has been designed. The main originality of our work is the extension of the operating frequency band of the uniplanar bowtie slot antenna to frequencies lower than 800 MHz. The shape and the dimensions of the antenna have been optimised in the presence of a soil using numerical simulations based on the finite difference time domain approach. For the characterisation of the sub-surface, a transmission link comprising a pair of bowtie slot antennas that are moved along the soil surface has been studied in details to obtain the system performance in the frequency and time domains. First experimental results have been obtained on a sandy soil in the frequency domain using a vector network analyser. The experimental data have been analysed and compared with simulations results.

A Compact Dual-Band Bow-Tie Slot Antenna for 900-MHz and 2400-MHz ISM Bands

In this letter, the overall size of a dual-band bow-tie slot antenna is reduced by modifying the design of the radiating slot and by extending the feeding coplanar transmission line. In particular, it is shown that by sweeping and rounding the edges of the radiating slots and by extending and terminating the feeding coplanar transmission line with a short circuit, the overall size of the antenna layout can be reduced by 47%. A dual-band prototype antenna is manufactured, and measured results are shown to compare very well with simulated values from two different commercial software packages. This letter presents two new techniques that are beneficial for reducing the overall size of a bow-tie slot antenna .

Novel bow-tie antenna on artificial magnetic conductor for 5.8 GHz radio frequency identification tags usable with metallic objects

A novel combination of coplanar waveguide-fed double bow-tie slot antenna and artificial magnetic conductor, which meets the requirements of 5.8 GHz super high frequency radio frequency identification tag antenna usable on metallic objects is presented. The electrical characteristics of the embedded structure are evaluated using finite-element method and method of moment techniques. The manufactured prototypes are characterised in terms of return loss, gain and radiation pattern measurements in an anechoic chamber, both alone and on a metallic plate.

Modeling, Design and Characterization of a Very Wideband Slot Antenna With Reconfigurable Band Rejection

An antenna exhibiting a very wide bandwidth with reconfigurable rejection within the band is presented. The proposed topology is versatile in terms of the number of available antenna states and location of the rejection frequencies, and also allows the operation of the antenna in an “all-pass” state. First, a physical interpretation of the rejection mechanism and its corresponding circuit model are presented and validated. The proposed antenna concept is then demonstrated on a 4-state slot bow-tie antenna operating from 1.5 to 5 GHz with various rejection frequencies. PIN diodes are used as switching elements, with particular care taken to minimize power consumption. Simulated and measured return loss, radiation patterns and gain of the fully operational antenna are presented. Finally, we characterize and discuss the overall efficiency-considered here as the most relevant parameter to characterize the antenna filtering performance-both theoretically and experimentally, thereby highlighting the benefit of the proposed topology.

A Compact Triband Bow-Tie Slot Antenna Fed by a Coplanar Waveguide

A uniplanar and compact bow-tie slot antenna capable of triband operation is proposed. Design considerations for the three operating frequencies are extensively discussed. Unlike most other multifrequency antennas having their sizes determined by the lower resonant frequency, the size of the proposed antenna is determined by the upper resonant frequency, and thus it is compact in nature. The middle and lower operating frequencies are obtained by inserting two metal strip pairs near the ends of the bow-tie slot without increasing the overall antenna area. Measured reflection coefficients are compared to the simulated ones with good agreement, and radiation patterns at the three operating frequencies are broadside and bidirectional and with satisfactorily low cross-polarization levels.

Novel Bow-tie–AMC Combination for 5.8-GHz RFID Tags Usable With Metallic Objects

A novel combination of coplanar waveguide (CPW)-fed double bow-tie slot antenna and artificial magnetic conductor (AMC), which meets the requirements of a 5.8-GHz SHF RFID tag antenna usable on metallic objects, is presented. The manufactured prototype is characterized in terms of return loss, gain, and radiation pattern measurements in an anechoic chamber, both alone and on a metallic plate.