Dipole Feed Research Articles

A Dual-Polarization Broadband Coupling Feed Dipole Antenna Based on Artificial Magnetic Conductor

A dual-polarized broadband coupled feed dipole antenna loaded with artificial magnetic conductor (AMC) structure is proposed. The proposed AMC structure with 4×4 elements shown in this paper consists of four perfect electrical conductor (PEC) rectangular strips and a ring to reduce the profile height of the dual-polarized dipole antenna. In addition, the dual-polarization antenna adopts coupling feed microstrip to excite two pairs of bow-tie patch. The overall size of the coupling feed dipole antenna is 1.1λ0×1.1λ0×0.09λ0 at 5.5 GHz. Measured results shows that the proposed dual-polarization antenna loaded AMC exhibit a 25.2% common working bandwidth (4.75-6.12 GHz). The isolation is less than -14 dB, and the peak gain is 10.6 dBi. This dipole antenna with AMC structure has the virtues of low profile, wide band, and good radiation performance and it has the potential to be used in C-band communication.

3D Printed Hemispherically Radiating Antenna for Broadband Millimeter Wave Applications

Nowadays, additive manufacturing provides far-reaching possibilities for use in radio frequency components. In addition to almost unlimited freedom of design as compared to conventional manufacturing, the absence of further assembly steps is a key aspect of 3D printing. In this paper, a 3D printed monolithic antenna for millimeter wave-sensing applications is presented with a full hemispherical coverage. The antenna is designed as an ensemble of a waveguide horn antenna and a differentially fed dipole antenna. The slotted waveguide approach was utilized to improve the manufacturing quality on the waveguide inside. The influence of two optimized antenna elements, a metal plane, and a cut-out window, on the beam pattern is comprehensively investigated. A huge half power beam width of 142° in both directions, elevation and azimuth, is presented at 79 GHz and a boresight gain of 4.7 dBi was measured. The beam pattern in the frequency range from 76 to 81 GHz is studied in greater detail, where a half power beam width of at least 112° is achieved. Due to the −10 dB matching capability bandwidth of over 28 GHz, the antenna is also suitable for extremely broadband applications with a −5 dB angular width of better than 100°. Furthermore, the system design describes how to integrate the antenna into hybrid circuit designs and the manufacturing tolerances are examined. The antenna offers attractive possibilities for millimeter wave-sensing applications in the area of assisted living and industrial monitoring, especially whenever blind spots have to be avoided.

Design of mmWave Foldable Vertically Stacked Yagi–Uda Antenna Inspired by Origami and Kirigami Theories

This letter presents a foldable vertically stacked Yagi–Uda antenna at millimeter-wave (mmWave) frequency band. The proposed antenna is built on a FR4 substrate. The antenna consists of a balun, feed dipole element, stacked folded dipole, and inside lamina emergent torsional (LET) joint array. The LET joint array is introduced to reduce and distribute the mechanical stress generated in folding the rigid FR4 substrate. In the planar mode, the antenna results in a measured gain value of 4.9 dBi at the design frequency 24 GHz with a cross-polarization suppression level of less than 12 dB. In the folded mode, the antenna has a measured gain value of 3.9 dB at the target frequency 24 GHz with a cross-polarization suppression level of less than 10 dB. Both operation modes of the proposed antenna cover the broad bandwidth from 23 to 28 GHz (about 20 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> ).

Design of the New Wideband Vivaldi Feed for the HERA Radio-Telescope Phase II

This article presents the design of a new dual-polarized Vivaldi feed for the Hydrogen Epoch of Reionization Array (HERA) radio telescope. This wideband feed has been developed to replace the Phase I dipole feed and is used to illuminate a 14 m diameter dish. It aims to improve the science capabilities of HERA, by allowing it to characterize the redshifted 21 cm hydrogen signal from the Cosmic Dawn as well as from the Epoch of Reionization. This is achieved by increasing the bandwidth from 100–200 to 50–250 MHz, optimizing the time response of the antenna–receiver system and improving its sensitivity. This new Vivaldi feed is directly fed by a differential front-end module placed inside the circular cavity and connected to the back end via cables that pass in the middle of the tapered slot. We show that this particular configuration has minimal effects on the radiation pattern and the system response.

Multi-Layer and Conformally Integrated Structurally Embedded Vascular Antenna (SEVA) Arrays.

This work presents the design and fabrication of two multi-element structurally embedded vascular antennas (SEVAs). These are achieved through advances in additively manufactured sacrificial materials and demonstrate the ability to embed vascular microchannels in both planar and complex-curved epoxy-filled quartz fiber structural composite panels. Frequency-reconfigurable antennas are formed by these structures through the pressure-driven transport of liquid metal through the embedded microchannels. The planar multi-layer topology examines the ability to fabricate two co-located radiating structures separated by a single ply of quartz fabric within the composite layup. The multi-element linear array topology composed of microchannels embedded on to a single-layer are used to demonstrate the ability to conformally-integrate these channels into a complex curved surface that mimics an array of antennas on the leading edge of an Unmanned Aerial Vehicle (UAV). A parallel-strip antipodal dipole feed structure provides excitation and serves as the interface for fluid displacement within the microchannels to facilitate reconfiguration. The nominal design of the SEVAs achieve over a decade of frequency reconfiguration with respect to the fundamental dipole mode of the antenna. Experimental and predicted results demonstrate the operation for canonical states of the antennas. Additional results for the array topology demonstrate beam steering and contiguous operation of interconnected elements in the multi-element structure.

Conformal Phased Array Antenna for Unmanned Aerial Vehicle With ±70° Scanning Range

Conformal antennas are practicable candidates to the aerodynamic platforms. A wide-angle scanning conformal phased array antenna for an unmanned aerial vehicle (UAV) platform is designed and presented in this article. An eight-element linear phased array loaded with frequency selective surface (FSS) operating in S-band is investigated. The horizontally polarized antenna element is designed based on a tapered slot feeding dipole. The antenna aperture can be easily conformed to the front wing airframe of the UAV due to the flexibility of the employed polyimide film. To fulfill the requirement of the airborne communication system, two kinds of FSSs are loaded on the dipole antenna to enhance the gain and reduce the 3 dB beamwidth of the main lobe in the elevation plane. To improve the active impedance matching when the beam scans to the large angles, a novel parasitic structure is proposed. Finally, a 1 ×8 linear conformal array prototype is simulated, fabricated, and measured. The experimental results indicate that the antenna array achieves a fractional bandwidth of 22.1% with ±70° scanning along the E-plane. The measured results validate the performance of the proposed conformal array and the design.

A Broadband Low-Profile Dual-Linearly Polarized Dipole-Driven Metasurface Antenna

A low-profile broadband metasurface antenna (MSA) with dual-linear polarization is developed. The developed MSA mainly consists of a 4 × 4 grid-slotted patch array, two pairs of orthogonally printed feeding dipole strips, two vertically grounded and orthogonally placed microstrip Γ-shaped feeding structures, and an intact ground plane. It is demonstrated that the strip-excited MSA excites a leaky wave mode, a surface wave mode, and a dipole mode to provide a wide operational bandwidth. The prototype, with an overall size of 0.65 λ0 × 0.65 λ0 × 0.07 λ0 (λ0 is the wavelength in free space at the center operating frequency) was fabricated and measured. Three modes with broadside radiation patterns for each port are simultaneously excited to create a wide impedance bandwidth 36% with the average gain value 9.3 dBi. Moreover, the port-to-port isolation and the cross-polarization discrimination (XPD) are, respectively, higher than 26 and 25 dB.

Design of a Wideband Coupled Feed Dipole Antenna for PCL Array Systems

This article proposes the design of a wideband coupled feed dipole antenna for Passive Coherent Location (PCL) systems. The proposed antenna consists of an internal direct feed dipole and an external coupled feed dipole. This coupled feed mechanism, which is often used in microstrip patch antennas, is applied to the dipole element for a wide matching bandwidth. To verify the operating principle of the proposed antenna, an equivalent circuit model is investigated along with some parametric studies of the coupling effect. The proposed antenna is then extended to an eight-element uniform circular array to confirm the beamforming performance for PCL systems. The results demonstrate that the coupled feed dipole element is more suitable to enhance the matching bandwidth compared to a conventional dipole antenna.

A Compact Slotted Patch Hybrid-Mode Antenna for Sub-6 GHz Communication

A compact hybrid-mode antenna is proposed for sub-6 GHz communication. The proposed antenna is composed of a slotted rectangular patch, a feeding dipole, and a balun. Three modes are sequentially excited in a shared patch to achieve a compact size. A prototype antenna with a major size of 0.48 λ0 × 0.31 λ0 × 0.16 λ0 (λ0 is the wavelength in the free space at the center of the operating frequency band) is fabricated and measured. The measured results demonstrate an impedance bandwidth of 56.87% from 2.97 GHz to 5.33 GHz and an average gain of approximately 8.00 dBi with 1 dB variation in the operating frequency band of 3.0–5.0 GHz. The proposed antenna can be an element for microbase stations in sub-6 GHz communication.

Dual‐linear polarisation reconfigurable broadband omnidirectional antenna

A dual-linear polarisation reconfigurable broadband omnidirectional antenna is proposed. The radiating structure consists of a slotted ring and an inner square loop, which can generate omnidirectional radiation based on characteristic mode analysis. A dipole feeding network is designed and four PIN diodes are loaded into the feeding network to change the current flow direction. The final dimensions of the proposed antenna are 0.2 × 0.2 λ 0 ( λ 0 is the free-space wavelength), with a low profile of 0.006 λ 0 . The measured results show that the antenna achieves an overlapped bandwidth of 49.6% (from 480.2 to 797.5 MHz) with | S 11 | < −10 dB and a gain variation between −1 and 0.4 dBi. The proposed antenna can be applied to a digital terrestrial television service and an unmanned aerial vehicle pattern measuring system.

Design and optimization of cross bow-tie dipole feed with cavity for FAST

A cross bow-tie dipole feed with cavity and symmetrical E and H plane pattern is presented for the Five hundred-meter Aperture Spherical radio Telescope (FAST). In this paper we describe the design, optimization and simulation results of a wide-band cross dipole feed with cavity covering the frequency range from 300 MHz to 600 MHz for FAST. The main goals of our design are to ensure that, (1) we cover the octave bandwidth, (2) the feed has symmetrical E and H plane pattern, and (3) the physical dimension is suitable for mounting it in the reserved position of the FAST feed cabin. The initial results indicate that we have met most of our design goals. This kind of feed had been equipped with the multi-beam receiver to carry out observation on the platform of FAST cabin.

Low-Profile Broadband Absorber Based on Multimode Resistor-Embedded Metallic Strips

This article proposes a new method to realize a low-profile broadband absorber. The unit cell of the proposed absorber consists of two layers: a lossy layer with four rotationally symmetric bent metallic strips embedded with two chip-resistors, which is modified from a doubly fed dipole antenna, and a metallic ground separated from the lossy layer by an air spacer. Three resonant modes of the metallic strip embedded with two chip-resistors are generated, and the current in the strip passes through the chip-resistors under different modes and it is finally consumed, resulting in energy dissipation. As a result, an ultrawideband absorber is realized. The designed absorber is fabricated and measured, and the measured absorption band with a fractional bandwidth of 127.9% is achieved for at least 10-dB reflectivity reduction under the normal incidence. In addition, the thickness of the designed absorber is only $0.08\lambda _{L}$ , where $\lambda _{L}$ is the wavelength at the lowest operating frequency.

Design and Development of Compact and Broadband Coaxially Fed Dipole Antenna Covering 500MHz to 2500MHz

In this paper a novel technique to enhance the bandwidth of 5:1 operating from 500MHz to 2500MHz for coaxially fed dipole antenna is presented with simulated and measured results. In modern scenario, Broadband Omni directional antennas are the preferred antennas for Electronic Warfare (EW) applications. Most of the communications especially for monitoring applications are carried out in HF, VHF and UHF bands. The antenna size reduction is achieved by shaping the antenna in a unique way without employing any matching circuits. The proposed antenna is well matched with VSWR ≤ 3:1 over the frequency band. Finally the antenna is optimized using CST Microwave Studio TM EM simulation software then practically implemented and evaluated for its characteristics. As the proposed antenna incorporates no matching and tuning networks, it can handle high power and is suited for Trans-Receive applications in communication.

Fixed frequency broadside–endfire beam steerable antennas

A novel reconfigurable broadside–endfire microstrip antenna is proposed. The beam steering is achieved by reconfiguring the ground plane. The ground plane can be reconfigured either into a high-impedance surface for broadside radiation or into a surface waveguide for endfire radiation. A DC bias line, not connected to the folded dipole feed in any way, is used to switch the PIN diodes. PIN diodes are soldered on the back of the antenna and have no possibility of interfering with the feed. The proposed antenna is designed to work at the ISM 2.45 GHz band with a combined 2:1 VSWR bandwidth of 110 MHz and a combined radiation coverage of 133° on the H-plane. A 5 V power supply or a 9 V battery can be used to operate the active antenna.

A Compact Dipole Antenna for DTV Applications by Utilizing L-Shaped Stub and Coupling Strip

In this study, a small dipole antenna for digital television (DTV) reception band (470-862 MHz) is developed. The antenna is composed of a pair of bent dipoles, which are coupling fed by a coaxial cable. The resultant antenna has compact size of 20×200×0.8 mm 3 . Two parasitically coupling strips are added to excite one additional resonance mode. Bent dipole antennas and feeding structures are fabricated on the different planes of the substrate to embed two L-shaped stubs, thus resulting in improvement of the impedance matching condition. After careful optimization of the geometrical parameters of the antenna, the resonances are merged and thus, a wide impedance bandwidth is obtained. The measured -6-dB bandwidth of the antenna in free space is 615 MHz (80.4%).

Numerical Modeling for Excitation and Coupling Transmission of Near Field Around the Metal Drilling Pipe in Lossy Formation

The wireless transmission of the logging signal by using metal drill pipe as a dipole antenna with an extremely asymmetric feeding is one of the potential techniques for logging (or measurement) while drilling (LWD, or MWD) and has drawn a lot of attention in recent decades. In this paper, a precise numerical model based on numerical mode matching (NMM) theory has been built for solving the very low-frequency radiation of the asymmetrical feeding dipole antenna in the layered background medium. First of all, the feeding gap of the antenna has been equalized as a magnetic current loop, and NMM numerical solutions have been applied to expand the field excited by the equivalent source, and then, the characteristics of input impedance and the near field radiated by the dipole have been calculated based on the field solutions. Furthermore, the results have been compared with the corresponding results of the “method of moments” and the “equivalent transmission line model,” respectively. The inference of the relevant parameters, such as the asymmetry of the feeding, the working frequency, the conductivity of the formation, the size of the insulating gap, the size of the casing, etc., on the transmission performance of the signal of electromagnetic MWD (EM-MWD) system has been discussed. In addition, the method for receiving the LWD signal transmitted to the ground is also evaluated, and an adaptive impedance matching scheme in transmitting terminal is proposed based on the numerical analysis in this paper.

Coplanar strip fed UWB antenna with a step cut

A novel compact coplanar strip fed dipole antenna with a step cut suitable for ultrawideband (UWB) application is developed. The antenna is evolved from an open ended slot line by symmetrically etching out two rectangular metallic parts from its upper inner corners. The antenna has −10 dB reflection coefficient from 3.1 to more than 12 GHz that covers the Federal Communication Commission (FCC) specified UWB frequency range. From the simulation and experimental studies, it is found that the proposed antenna delivers moderate gain and stable radiation patterns over the operating band. Time domain analysis on the proposed antenna has been conducted and was found that the antenna can be used for UWB applications. The proposed antenna occupies a compact size of 28.5 × 10 × 1.6 mm3. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:665–672, 2014.

Constant Radiation Characteristics for Log-Periodic Dipole Array Antennas

Given the correct terminal voltages on each element of a log-periodic dipole array constant radiation characteristics can be achieved for an omni-directional radiation pattern. In this communication it is shown that this can only be achieved through optimization, correcting a previously reported oversimplification which resulted in an analytical approach being tractable. This oversimplification assumed that vanishing terminal currents on a dipole's terminal/feed element implies no radiation from that dipole. This is clearly non-physical because, zeroing the terminal current on a dipole's feed element is the same as disconnecting its two arms, while having no radiation from that dipole implies that in effect both arms be entirely removed. We show that the effect of currents induced in the disconnected arms of a dipole cannot in general be ignored.

Near-Zero-Index Metamaterial Lens Combined With AMC Metasurface for High-Directivity Low-Profile Antennas

A high-gain reduced-profile antenna is designed by combining the effects of a near-zero-index volumetric metamaterial lens and an artificial magnetic conducting (AMC) ground plane. The AMC/metalens antenna design presented here has 20% reduced height over an equivalent metalens antenna with conventional metallic ground plane at the cost of reduced peak directivity and pattern bandwidth. Both the metamaterial unit cells and the mushroom-type AMC structure are designed independently and retuned in the presence of the other for optimal performance. The lens collimates the electromagnetic radiation of a dipole feed by refraction as well as via a Fabry-Perot cavity effect, with resulting gain and patterns that are better than either mechanism can achieve individually. Full wave simulations of the entire metamaterial and AMC structure with a feed dipole agree well with measurements of the fabricated design.

Design of an implantable CPW fed dual dipole antenna for dual band biomedical applications

An implantable Coplanar Waveguide (CPW) fed dipole antenna operates in the Industrial, Scientific Medical (ISM) band and Wireless Medical Telemetry Services (WMTS) band for biomedical applications. The proposed implanted antenna is made compatible for implantation by embedding it in an alumina ceramic substrate. The proposed antenna was simulated using the method of moment's software IE3D by assuming the predetermined dielectric constant for the human body muscle, fat and skin tissues, and the parameters of an implantable antennas such as return loss, radiation pattern and Voltage Standing Wave Ratio (VSWR) with human body phantom liquid are plotted and it is verified with simulated results. The proposed antenna shows the lower return loss, perfect impedance matching and high gain as compared to other implanted antennas. The experiments permitted to identifying the most efficient tissue placements, and proposing some quantitative and general guidelines useful to characterise and design this kind of new system.