Analysis and optimized design of single feed circularly polarized microstrip antennas
TL;DR: In this article, three types of single-feed circularly polarized microstrip antennas, namely, a diagonal fed nearly square, a truncated-corners square and a square with a diagonal slot, are presented.
Abstract: Analysis and optimized designs are presented of three types of single feed circularly polarized microstrip antennas, namely, a diagonal fed nearly square, a truncated-corners square and a square with a diagonal slot. The Green's function approach and the desegmentation methods are used. The resonant frequencies are calculated for two orthogonal modes which together yield circular polarization. Optimum feed locations are determined for the best impedance match to a 50 \Omega coaxial feed line. Axial-ratio bandwidths, voltage standing-wave ratio (VSWR) bandwidths and radiation patterns are evaluated and verified experimentally.
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TL;DR: In this article, the authors proposed broadband impedance matching as a natural way to increase the bandwidth of conventional microstrip patch antennas and found that by using an optimally designed impedance-matching network, the bandwidth can be increased by a factor of at least 3.9, the exact value depending on the degree of matching required.
Abstract: The nature of the inherent narrow bandwidth of conventional microstrip patch antennas is considered. It is observed that, except for single-feed circularly polarized elements, their bandwidth is limited only by the resonant behavior of the input impedance and not by radiation pattern or gain variations, which usually are negligible over a moderate 10 to 20% bandwidth. Therefore, broadband impedance matching is proposed as a natural to increase the bandwidth. The maximum obtainable bandwidth is calculated using Fano's broadband matching theory. It is found that by using an optimally designed impedance-matching network, the bandwidth can be increased by a factor of at least 3.9, the exact value depending on the degree of matching required. A transmission-line prototype for a proper matching network is developed. The translation of this prototype network into a practical structure (e.g. a microstrip or stripline circuit) is considered. Practical design examples and experimental results which clearly show the validity of the technique are given. >
388 citations
TL;DR: In this paper, a method for increasing the bandwidth of microstrip patch antennas by incorporating two additional resonators which are gap-coupled to the radiating edges of a rectangular patch is described.
Abstract: A method for increasing the bandwidth of microstrip patch antennas by incorporating two additional resonators which are gap-coupled to the radiating edges of a rectangular patch is described. A two-dimensional analysis using Green's function and segmentation method is used for analyzing the proposed antenna configurations. A bandwidth as large as five times a single rectangular patch is obtained in S -band. Changes in the radiation pattern over this wide bandwidth are discussed. Experimental results are in reasonable agreement with the analysis.
280 citations
TL;DR: In this article, a single-feed configuration based asymmetric-circular shaped slotted square microstrip patches are adopted to realize the compact circularly polarized microstrip antennas with slits.
Abstract: Novel asymmetric-circular shaped slotted microstrip patch antennas with slits are proposed for circularly polarized (CP) radiation and radio frequency identification (RFID) reader applications. A single-feed configuration based asymmetric-circular shaped slotted square microstrip patches are adopted to realize the compact circularly polarized microstrip antennas. The asymmetric-circular shaped slot(s) along the diagonal directions are embedded symmetrically onto a square microstrip patch for CP radiation and small antenna size. The CP radiation can be achieved by slightly asymmetric (unbalanced) patch along the diagonal directions by slot areas. Four symmetric-slits are also embedded symmetrically along the orthogonal directions of the asymmetric-circular shaped slotted patch to further reduce antenna size. The operating frequency of the antenna can be tuned by varying the slit length while keeping the CP radiation unchanged. The measured 3-dB axial-ratio (AR) bandwidth of around 6.0 MHz with 17.0 MHz impedance bandwidth is achieved for the antenna on a RO4003C substrate. The overall antenna size is 0.27λo × 0.27λo × 0.0137λo at 900 MHz.
268 citations
Cites background or methods from "Analysis and optimized design of si..."
...The square patch and the CP truncated corners square patch radiators [5] are shown in Fig....
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...Various techniques have been published [5]–[10] to generate the CP radiation of the single-feed microstrip antennas....
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...The single-feed square patch was proposed by Sharma and Gupta for CP radiation using the symmetric truncated corners method [5]....
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TL;DR: In this article, a single-fed low profile cavity backed crossed slot antennas for dual frequency dual linear polarization and circular polarization applications are proposed by employing the substrate integrated waveguide (SIW) technique in the antenna designs.
Abstract: Single fed low profile cavity backed crossed slot antennas for dual frequency dual linear polarization and circular polarization applications are first presented in this paper. By employing the substrate integrated waveguide (SIW) technique in the antenna designs, the low profile backed cavity structure can be realized by using only a single layer of low cost printed circuit board (PCB) substrate. A single grounded coplanar waveguide (GCPW) is employed as the feeding element to excite the TE 120 and TE 210 modes in the SIW cavity. A crossed slot structure is used as the radiating element in order to radiate the desired dual linearly or circularly polarized wave. From the measurement results, it is seen that these novel antennas retain the advantages of conventional metallic cavity backed antennas, including high gain, high front-to-back ratio (FTBR), and low cross polarization level (CPL). Furthermore, the proposed antennas also possess the advantages of low profile, light weight, low fabrication cost, and easy integration with planar circuits.
263 citations
Cites background from "Analysis and optimized design of si..."
...Diagonal probe fed patch antennas with different perturbations have been discussed in [8]....
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...Its single GCPW feed element appears to generate parasitic radiation, which is higher than that generated by the aperture coupled feed element or the probe feed element employed in [8], [9], [13], [14]....
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TL;DR: In this article, a compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated.
Abstract: A novel compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated. Experimental results show that the proposed compact CP design can have an antenna-size reduction of about 36% as compared to the conventional corner-truncated square microstrip antenna at a given operating frequency. Also, the required size of the truncated corners for CP operation is much greater than that for the conventional CP design using a simple square microstrip patch, providing a relaxed manufacturing tolerance for the proposed compact CP design. Details of the experimental results are presented and discussed.
253 citations
Cites background from "Analysis and optimized design of si..."
...It is then found that, from experimental results, the required size of truncated corners for CP operation increases with increasing antenna-size reduction....
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References
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TL;DR: A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques, and critical needs for further research and development for this antenna are identified.
Abstract: A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and finite-element techniques. Practical procedures are given for both standard rectangular and circular patches, as well as variations on those designs including circularly polarized microstrip patches. The quality, bandwidth, and efficiency factors of typical patch designs are discussed. Microstrip dipole and conformal antennas are summarized. Finally, critical needs for further research and development for this antenna are identified.
1,598 citations
TL;DR: In this paper, a new class of antennas using microstrips to form the feed networks and radiators is presented in this communication, which have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) low profile conformal design.
Abstract: A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.
608 citations
Proceedings Article•
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TL;DR: In this paper, the design procedures for both linearly and circularly polarized antennas are discussed for both UHF and C band and measured patterns are presented for antennas from UHF through C band.
Abstract: Microstrip antennas consist of a planar resonant radiating element parallel to, but separated, from a ground plane by a thin dielectric substrate ( t \ll \lambda ). These antennas are very thin and consequently rugged and easy to mount. They may be fed from the back through the ground plane or from the edge by depositing microstrip lines on the dielectric substrate. Several varieties of microstrip antennas are discussed in this paper. Design procedures are given for both linearly and circularly polarized antennas. Measured patterns are presented for antennas from UHF through C band.
275 citations
TL;DR: It is shown that a computer analysis based upon a contour-integral solution of the wave equation offers an accurate and efficient tool in the design of the planar circuit.
Abstract: Three principal categories have been known in electrical circuitry so far. They are the lumped-constant (0-dimensional) circuit, distributed-constant (1-dimensional) circuit, and waveguide (3-dimensional) circuit. The planar circuit to be discussed in general in this paper is a circuit category that should be positioned as a 2-dimensional circuit. It is defined as an "electrical circuit having dimensions comparable to the wavelength in two directions, but much less thickness in one direction." The main subject of this paper is the computer analysis of an arbitrarily shaped, triplate planar circuit. It is shown that a computer analysis based upon a contour-integral solution of the wave equation offers an accurate and efficient tool in the design of the planar circuit. Results of some computer calculations are described. It is also shown that the circuit parameters can be derived directly from Green's function of the wave equation when the shape of the circuit is relatively simple. Examples of this sort of analysis are also shown for comparison with the computer analysis.
207 citations
TL;DR: In this paper, the analysis of two-dimensional microwave planar circuits is modified by using Z-matrices for the individual planar segments, which is shown to be computationally more efficient.
Abstract: Segmentation method for the analysis of two-dimensional microwave planar circuits is modified by using Z-matrices for the individual planar segments. The proposed method is compared with the previously reported method using S-matrices and is shown to be computationally more efficient.
152 citations