# An experimental investigation of electrically thick rectangular microstrip antennas

TL;DR: In this paper, the electromagnetic properties of rectangular microstrip antennas were investigated experimentally, and the bandwidth was calculated as a function of electrical thickness and the antenna radiation patterns were measured.

Abstract: The electromagnetic properties of electrically thick rectangular microstrip antennas were investigated experimentally. Antennas were fabricated with different patch sizes and with electrical thicknesses ranging from 0.03 to 0.23 wavelengths in the dielectric substrate. The resonant frequencies were measured and compared to existing formulas. The bandwidth was calculated as a function of electrical thickness and the antenna radiation patterns were measured.

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TL;DR: In this paper, the characteristics of a rectangular microstrip antenna with an L-shaped probe are investigated and a foam layer with a thickness of around 10% of the wavelength is used as the supporting substrate.

Abstract: The characteristics of a rectangular microstrip antenna with an L-shaped probe are investigated. A foam layer with a thickness of around 10% of the wavelength is used as the supporting substrate. An impedance bandwidth of 35% and an average gain of 7.5 dBi can be achieved. The radiation pattern is stable across the passband.

455 citations

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TL;DR: In this paper, the analysis of resonant-type antennas based on the fundamental infinite wavelength supported by certain periodic structures is presented, and the analysis and design of the required unitcell is discussed based upon field distributions and dispersion diagrams.

Abstract: The analysis of resonant-type antennas based on the fundamental infinite wavelength supported by certain periodic structures is presented. Since the phase shift is zero for a unit-cell that supports an infinite wavelength, the physical size of the antenna can be arbitrary; the antenna's size is independent of the resonance phenomenon. The antenna's operational frequency depends only on its unit-cell and the antenna's physical size depends on the number of unit-cells. In particular, the unit-cell is based on the composite right/left-handed (CRLH) metamaterial transmission line (TL). It is shown that the CRLH TL is a general model for the required unit-cell, which includes a nonessential series capacitance for the generation of an infinite wavelength. The analysis and design of the required unit-cell is discussed based upon field distributions and dispersion diagrams. It is also shown that the supported infinite wavelength can be used to generate a monopolar radiation pattern. Infinite wavelength resonant antennas are realized with different number of unit-cells to demonstrate the infinite wavelength resonance

451 citations

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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

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TL;DR: In this paper, the L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength), and a parametric study on the rectangular patch antenna is presented.

Abstract: The L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength). A parametric study on the rectangular patch antenna is presented. It is found that the antenna attains 36% impedance bandwidth (SWR/spl les/2) as well as gain bandwidth and about 7-dBi average gain. A two-element array fed by L-probes is also proposed. Experiments show that the array design can substantially suppress the cross polarization of the proposed antenna. Both the antennas have stable radiation patterns across the passband. Moreover, the measured resonant frequencies of the proposed antenna agree well with an existing formula and the L-probe does not have much effect on the resonant frequency.

382 citations

### Cites methods from "An experimental investigation of el..."

...Several methods including the utilization of parasitic patches [1] and thick substrates [ 2 ] have been suggested in the literature....

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TL;DR: In this article, a microstrip feedline on a substrate proximity-coupled to a rectangular microstrip patch on a covering superstrate is constructed, and a small open-circuit tuning stub is connected in shunt with the feed line.

Abstract: The letter presents experimental results for a proximity-coupled microstrip patch antenna capable of 13% bandwidth. The impedance match (VSWR ≤ 2), copolarised radiation patterns and crosspolarised radiation were measured over this bandwidth to confirm operation. The construction is quite simple, consisting of a microstrip feedline on a substrate proximity-coupled to a rectangular microstrip patch on a covering superstrate; a small open-circuit tuning stub is connected in shunt with the feed line.

301 citations

##### 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

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01 Oct 1975TL;DR: In this article, a method for determining the accuracy of computed impedance and wavelength data for microstrip is proposed and a simple, accurate equation for the microstrip open circuit is presented.

Abstract: A method for determining the accuracy of computed impedance and wavelength data for microstrip is proposed. It is shown that the standard equations of Wheeler and Schneider have rather large errors. Revised equations for microstrip impedance and wavelength are given both for analysis and synthesis with accuracy better than 1%. A simple, accurate equation for the microstrip open circuit is presented. Experimental data on microstrip T-junctions are compared with existing theories. A new accurate equation is given for the reference plane displacement in the stub arm. Corrections are proposed in the existing equations for the other parameters of the equivalent circuit.

514 citations

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TL;DR: In this paper, the performance of printed antenna elements on substrates which may be electrically thick, as would be the case for printed antennas at millimeter wave frequencies, is investigated, and an optimization procedure for maximizing or minimizing power launched into surface waves from a multielement printed antenna array is presented.

Abstract: Calculated data are presented on the performance of printed antenna elements on substrates which may be electrically thick, as would be the case for printed antennas at millimeter wave frequencies. Printed dipoles and microstrip patch antennas on polytetrafluoroethylene (PTFE), quartz, and gallium arsenide substrates are considered. Data are given for resonant length, resonant resistance, bandwidth, loss due to surface waves, loss due to dielectric heating, and mutual coupling. Also presented is an optimization procedure for maximizing or minimizing power launched into surface waves from a multielement printed antenna array. The data are calculated by a moment method solution.

470 citations

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TL;DR: In this paper, a technique for controlling the operating frequency and polarization of microstrip antennas is proposed, which is achieved by placing shorting posts at appropriate locations within the antenna's boundaries.

Abstract: A technique is investigated for controlling the operating frequency and polarization of microstrip antennas. The control is achieved by placing shorting posts at appropriate locations within the antenna's boundaries. By changing the number and locations of the posts, the operating frequency can be tuned over a 1.5-to-1 range, and the polarization can be changed from horizontal to vertical, right-hand circular, or left-hand circular. All of these changes are obtained without significantly altering the input impedance or radiation patterns of the antenna and without increasing the complexity of the external microwave feed network. The frequency and polarization can be electronically controlled by using microwave switching diodes for the shorting posts. Antennas that have two feeds and operate simultaneously in two orthogonal polarizations have been constructed with the capability to switch between linear and circular polarization. Also, a thin frequency-scanned array has been built with the frequency-agile microstrip elements.

311 citations

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15 Mar 1978TL;DR: In this paper, the dual-frequency behavior of a pair of stacked circular-disc printed-circuit antennas is investigated experimentally and the input impedance is measured as a function of the sizes of the discs with emphasis placed on the values of the two resultant resonant frequencies.

Abstract: The dual-frequency behavior of a pair of stacked circular-disc printed-circuit antennas is investigated experimentally. The input impedance is measured as a function of the sizes of the discs with emphasis placed on the values of the two resultant resonant frequencies.

227 citations