Resistive and Inductive Loading Techniques on Microstrip Antenna for Wideband Application

A spherical ultra-wideband antenna is proposed based on a self-complementary structure. The antenna employs a loop comprising two symmetric teardrop-shaped arms conformally printed on a three-dimensional (3D) sphere. To enhance the impedance matching bandwidth, inductive and capacitive loadings are applied to the antenna by adding shorting strips at the antenna’s rear part and broadening the front part respectively. Measurement results show that the proposed antenna is capable of covering the frequency range of 0.8–8 GHz with a low reflection coefficient(S11) ≤ − 10 dB, gain > 2.8 dB, and radiation efficiency > 63%.

Microstrip antennas or patch antennas are popular for their attractive features such as low profile, low weight, low cost, ease of fabrication and integration with RF devices. Micro strip antennas have been found favorable because they are inexpensive to manufacture and compatible with monolithic microwave integrated circuit designs (MMIC). They are usually employed at UHF and higher frequencies because the size of the antenna is directly tied to the wavelength at the resonance frequency. A Microstrip or patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. The most commonly employed microstrip antenna is a rectangular patch. The major disadvantages of Microstrip antennas are lower gain and very narrow bandwidth. Microstrip patch antennas have some drawbacks of low efficiency, narrow bandwidth (3-6%) of the central frequency. Millimeter wave technology being an emerging area is still much undeveloped. As micro strip antennas have found wide variety of application areas, a number of techniques are evolved to improve its limited bandwidth. A good approach to improve the bandwidth is increasing the thickness of substrate supporting the micro strip patch. However problems exist on the ability to effectively feed the patch on a thick substrate and the radiation efficiency can degrade with increasing substrate thickness. A substantial research needs to be done in this area as its applications are numerous. The radiation patterns and S11 performance are used for the analysis of the different configurations. In the present endeavor a rectangular patch antenna is designed on thick substrate and simulated using MATLAB software and configuration on different dielectric susbstrates was used .

This chapter contains sections titled: A Review of Some Microstrip Antenna Characteristics Conformal Microstrip Antennas and Microstrip Phased Arrays An Experimental Investigation of Electrically Thick Rectangular Microstrip Antennas The Effect of Various Parameters of Circular Microstrip Antennas on Their Radiation Efficiency and the Mode Excitation Crosspolarisation Characteristics of Circular Patch Antennas Guidelines for Design of Electromagnetically Coupled Microstrip Patch Antennas on Two-Layer Substrates Design of Microstrip Antennas Covered with a Dielectric Layer The Finite Ground Plane Effect on the Microstrip Antenna Radiation Patterns

A generic integrated optoelectronic-to-VLSI packaging technology using silicon substrate and etched silicon optical submount has been developed and demonstrated. The miniature silicon submount that interfaces optical fiber with the optoelectronic component and the silicon substrate containing VLSI circuits is fabricated with double-sided nonplanar photolithography and anisotropic etching techniques. The advantages of this technology are: ability to interface optical information and circuits with VLSI in a single package; precision controlled capacitive, resistive, and inductive loading; minimized distance between optoelectronic components and electronic ICs, and between decoupling capacitors and active circuits; self-aligned fiber insertion; and highly automated manufacturing. These advantages translate to higher functional density and performance at a lower cost than conventional optoelectronic packaging technologies. >

For satellite communications terminals, the radiation efficiencies typically achieved by microstrip antennas (MSA) are inadequate. To realize more efficient planar antennas for this application, the dependence of radiation efficiency on two key parameters, substrate relative dielectric constant and thickness, was investigated, and substrate selection guidelines were developed for high radiation efficiency antenna design. Based on the selected substrate, two types of MSA array feeds for Ku band satellite communication were designed, simulated, fabricated and measured for radiation efficiency comparison. One of the MSA arrays achieved a radiation efficiency of 93% at 12 GHz, which is among the best reported efficiencies for this frequency and class of antennas.

Microstrip Antennas (MSAs) have several advantages, including that they are light weight and small volume and that they can be made conformal to the host surface. In addition, MSAs are manufactured using printed circuit technology, so that mass production can be achieved at a low cost. In comparison to traditional antenna elements, however, the electrical performance of the basic microstrip antenna suffers from a number of serious drawbacks, e.g. narrow bandwidth; high feed network losses, poor cross polarization, and low power handling capacity. The major disadvantage of the microstrip-patch antenna is its inherently narrow impedance bandwidth of only a couple of percent. Intensive research is going on to develop bandwidth-enhancement techniques by keeping its size as small as possible. Accordingly, increasing the bandwidth of the MSA has been a primary goal of research in the field. We present here a compact two-layer electromagnetically coupled patch antenna with an impedance bandwidth of 35%. The radiation efficiency is obtained 90% in the operating band. The designed antenna is right-hand circularly polarized and operates in the 2.4 GHz ISM-band frequency The proposed structure has been initially optimized using IE3D software followed by experimental verification on Agilent Vector Network Analyzer, E5062A.

The author describes a resistively loaded triangular dipole design which is only 0.30 wavelengths long, yet exhibits a VSWR (voltage standing wave ratio) of better than 2.0:1 when mounted in front of the backplane. This improvement in VSWR is at the expense of only a 3 dB decrease in element efficiency. The decrease in efficiency can be directly controlled by the value of the resistive loading. The element has been implemented in a printed circuit array fed by tapered line baluns operating over a 4:1 frequency band. Measured input impedance data vs. loading value is presented, as well as the radiation pattern variation over the band. >

Generation of electro-acoustic waves by an antenna immersed in a plasma medium affects the radiation efficiency of the antenna. Microstrip antennas mounted on space vehicles and satellites encounter ionized medium during their voyage in space. The generation of the electro acoustic waves by a linearly-polarized microstrip antenna and its effect on radiation efficiency of the antenna is studied in this paper. A well-established hydrodynamic theory and vector wave function technique is used to derive the expression for field pattern and radiated power by the antenna. The radiation efficiency for the antenna for different plasma frequency is computed and compared with radiation efficiency of linear antennas in plasma. It is concluded that the radiation efficiency of the microstrip antenna decreases with plasma frequency. However, it is higher than the corresponding efficiency of the linear antenna.

In this paper theoretical comparison of the efficiency of planar microstrip antenna for normal metal copper and high temperature superconducting (HTS) metal is discussed. Expressions for electrical conductivity and surface impedance in copper and high-temperature superconductor YBa <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Cu <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</inf> are evaluated at 10GHz frequency. Direct fed rectangular microstrip patch has been selected for the comparison. The electrically small antenna has been designed at 10 GHz frequency on high permittivity substrate LaAlO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> with a low dielectric loss tangent. The radiation patterns at 10GHz and the radiation efficiency as a function of frequency for microstrip antenna have been compared using software simulation.

The conventional Wheeler cap method usually produces accurate radiation efficiency of small antennas when the antennas under test (AUTs) operate as a simple series or a parallel RLC resonance circuit. However, this method often gives unreliable radiation efficiency if the AUT has a complicated operating principle such as circular polarization (CP), multiple resonances, or broad-band properties. In this paper, we propose an improved Wheeler cap method based on the equivalent high-order circuit model including transformers to provide accurate radiation efficiency, although the AUT does not operate as a simple resonance circuit. For building equivalent high-order circuit models, a method for estimating the initial values of a genetic algorithm (GA) is also proposed, which effectively reduces the searching space and improves the convergence of the optimization. To verify the proposed method, we measure the radiation efficiency of a CP microstrip antenna, a UHF RFID tag antenna, and a triple-resonance microstrip antenna.

A 1/10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> scaled prototype pulse modulator for an Inertial Electrostatic Confinement (IEC) neutron source has been designed and tested at Los Alamos National Laboratory (LANL). The scaled prototype modulator is based on a solid-state Marx architecture and has an output voltage of 13 kV and an output current of 10 A. The modulator has a variable pulse width between 50 ¿s and 1 ms with < 5% droop at all pulse widths. The modulator operates with a duty factor up to 5% and has a maximum pulse repetition frequency of 1 kHz. The use of a solid-state Marx modulator in this application has several potential benefits. These benefits include variable pulse width and amplitude, inherent switch overcurrent and transient overvoltage protection, and increased efficiency over DC supplies used in this application. Several new features were incorporated into this design including inductorless charging, fully snubberless operation, and stage fusing. The scaled prototype modulator has been tested using a 1 k¿ resistive load, Test results are given. Short (50 ¿s) and long (1 ms) pulses are demonstrated as well as high duty factor operation (1 kHz rep rate at a 50 ¿s pulse width for a 5% duty factor). Pulse agility of the modulator is demonstrated through turning the individual Marx stages on and off in sequence producing ramp, pyramid, and reverse pyramid waveforms.

A 16-port shared-arm dipole array (SADA) is designed and its performance verified. When constructing a 2D physical array to image a target, arranging the antenna elements in a longitudinal direction becomes problematic due to the element spacing constraint for alias-free sampling. Therefore, the proposed structure is designed such that the two dipole elements share a single arm, which leads to alias-free sampling in the aperture domain. In order to improve the performance of the SADA, each antenna arm is loaded with a constant resistive profile. The resistive loading allows each element to operate over a broad-band and radiate a temporally short pulse, while correcting the distorted beam pattern of the SADA. The resultant 16-port SADA with resistive loading is manufactured by printing the arms on an FR-4 substrate and loading them with equally spaced chip resistors. The performance of the 16-port SADA as a sensor array for an imaging radar is then verified by an experiment.

This paper presents a compact slotted rectangular microstrip antenna with modified ground plane. Performance advancements with simple modifications of a reference antenna has been carried out in the entire work. The radiating patch and the ground surface has been loaded by two asymmetrical slots and two symmetrical slots respectively. This slight change in antenna shape makes the microstrip antenna more compact. In addition, the directivity, gain, and radiation efficiency have been enhanced significantly. The overall antenna size is 41.3 mm × 48.5 mm × 1.6 mm. The proposed antenna provides 19.8% of the compactness along with 2.9dB of gain enhancement, directivity boost of 2.5dB and radiation efficiency improvement of 25%, approximately. An acceptable relationship is observed between co and cross polarization from achieved patterns which imply the antenna structure as a qualified radiator in terms of polarization purity. A prototype is fabricated with proper characterization. The measured results have a good agreement with simulated results.

Micro Strip Patch Antenna for WLAN/WiMAX Applications: A Review

A Microstrip antennas have specific characteristics such as a low profile, low volume, little power consumption, concentration, and easy manufacture. Due to these capabilities, Microstrip antennas can overcome rising wireless communication requirements such as high gain, high power, high performance and low losses. Since it can be printed directly onto a circuit board, microstrip antennas are becoming more common. Cell phones are increasingly utilizing microstrip antennas. Antenna designs proposed in literature are on big in size. The antenna structure's operating bandwidth should be greater than the structures suggested in the literature sample. Usually, the antenna structure's fractional bandwidth should be greater than 100%. The structure's total dimensions should be as minimal as possible. The structure's total measurements will be 25x25x1.5 mm3. The antenna system should be able to radiate more signals thus minimizing losses caused by surface waves. The structure's targeted radiation efficiency should be greater than 50%. The structure must be fabricated on a low-cost FR4 substrate that is commercially available in lower cost. The proposed work aimed at improving the efficiency of the microstrip antenna would be ideal for Wi-Fi, WiMAX, WLAN, and other UWB wireless networking applications.