Microstrip Patch Antennas Fed by Substrate Integrated Waveguide

Dizertační práce je zaměřena na výzkum mikropáskových flíčkových antén a anténních řad napájených vlnovodem integrovaným do substrátu (SIW). Využitím vlnovodu integrovaného do substrátu pro napájení mikropáskové flíčkové antény dochází ke kombinaci výhodných vlastností obou struktur. Výsledkem je kompaktní anténní struktura, jejíž napájecí vedení neprodukuje parazitní záření a neovlivňuje tak vyzařovací charakteristiku antény. Práci lze z věcného hlediska rozdělit do dvou částí. První část práce (kapitola 2) je zaměřena na návrh flíčkových antén a jejich navázání na vlnovod integrovaný do substrátu. První dvě navržené flíčkové antény využívají vlnovod integrovaný do substrátu a štěrbinu nebo koaxiální sondu pro buzení lineárně polarizované vlny. Napájení koaxiální sondou je dále použito pro buzení kruhově polarizované flíčkové antény. Za účelem získání širšího pásma osového poměru je navrženo napájení flíčkové antény ve dvou bodech. Funkčnost všech anténních struktur je popsána pomocí parametrických simulací a ověřena realizací a měřením vyrobených prototypů antén. Prezentované napájecí metody představují nový způsob napájení pro mikropáskové antény využívající technologii SIW. Ve druhé části práce (kapitola 3) je pojednáno o implementaci štěrbinou napájené mikropáskové anténní struktury do malých anténních polí o velikosti 2x2 a 1x4. V případě lineární řady je uvažováno amplitudové rozložení pro optimální potlačení postranních laloků. Obě navržené anténní řady jsou ověřeny měřením a v porovnání s podobnými anténními řadami dostupnými v literatuře dosahují širšího pracovního pásma kmitočtů a vyššího zisku.The thesis deals with the research of microstrip patch antennas and antenna arrays fed by a substrate integrated waveguide (SIW). Exploiting an SIW structure for microstrip patch antenna feeding combines the benefits of both structures. The result is a compact antenna structure retaining advantageous properties of microstrip patch antennas and having a radiation characteristic non-effected by spurious radiation which is usually produced by a conventional feeding line. The thesis consists of two factual parts. The first one (Chapter 2) deals with the design of microstrip patch antennas and exploiting a substrate integrated waveguide for their feeding. The first two microstrip patch antennas exploit an SIW and a slot or a coaxial probe in order to excite a linearly-polarized wave. SIW-based probe feeding is further utilized for exciting a single- and dual-fed circularly-polarized microstrip patch. The functionality of the proposed antenna structures is described using parametric analyses and verified by measuring of fabricated prototypes. The proposed feeding methods represent a novel feeding approach for microstrip patch antennas exploiting SIW technology. The second part of the thesis (Chapter 3) deals with implementing the linearly-polarized aperture-coupled microstrip patch antenna structure fed by SIW into two small antenna arrays consisting of 2x2 and 1x4 radiators. An amplitude distribution is considered in the case of the linear antenna array for optimum suppression of side lobes. Both proposed antenna arrays are verified by measurements. Compared to similar antenna arrays available in the literature, they reach a wider operating frequency band and a higher gain.

Antenna Array Designs For Directional Wireless Communicatoin

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Reconfigurable Wideband Circularly Polarized Microstrip Patch Antenna for Wireless Applications

In this thesis, developments of rectangular microstrip patch antenna to have circular polarization agility with wideband performance, for wireless applications are presented. First, a new technique to achieve circularly polarized (CP) probe feed single-layer microstrip patch antenna with wideband characteristics is proposed. The antenna is a modified form of the popular E-shaped patch, used to broaden the impedance bandwidth of a basic rectangular patch antenna. This is established by letting the two parallel slots of the E-patch unequal. Thus, by introducing asymmetry two orthogonal currents on the patch are excited and circularly polarized fields are realized. The proposed technique exhibits the advantage of the simplicity inherent in the E-shaped patch design. It requires only slot lengths, widths, and position parameters to be determined. Also, it is suitable for later adding the reconfigurable capability. With the aid of full-wave simulator Ansoft HFSS, investigations on the effect of various dimensions of the antenna have been carried out via parametric analysis. Based on these investigations, a design procedure for a CP E-shaped patch is summarized. Various design examples with different substrate thicknesses and material types are presented and compared, with CP U-slot patch antennas, recently proposed in the literature. A prototype has been constructed following the suggested design procedure to cover the IEEE 802.11b/g WLAN band. The performance of the fabricated antenna was measured and compared with the simulation results for the reflection coefficient, axial ratio, radiation pattern, and antenna gain. Good agreement is achieved between simulation and measured results demonstrating a high gain and wideband performance. Second, a polarization reconfigurable single feed E-shaped patch antenna with wideband performance is proposed. The antenna is capable of switching from right-hand circular polarization (RHCP) to left-hand circular polarization (LHCP) and vice versa, with the aid of two RF PIN diodes that act as RF switches. The proposed structure which is simple; consists of a single-layer single fed radiating E-shaped patch and RF switch placed on each of its slots at an appropriate location. The design targets WLAN IEEE 802.11b/g frequency band (2.4- 2.5 GHz) as one example of the wireless applications. The idea is based on the first proposed design. In other words, if one of the switches is ON and the other is OFF, the two slot lengths will become effectively unequal and circular polarization will be obtained. If the states of the two switches are reversed, circular polarization with opposite orientation will be obtained at the same frequency band. Full-wave simulator Ansoft HFSS is again used for the analysis. Complete detailed DC biasing circuit of the switches for integration with the antenna is presented. Also, characterizations of the microwave components used in the biasing circuit are discussed. Antenna prototype has been fabricated and tested. Simulation results along with the measured one, for the reflection coefficient, axial ratio, radiation pattern, and antenna gain agree well, showing wide bandwidth and high gain for the two circularly polarized modes

Circularly Polarized Proximity-Fed Microstrip Array Antenna for Micro Satellite

Design of circular polarization microstrip antenna array was developed to support micro-satellite technology. Circular polarization antenna array used for data transmission applications operating in the S band frequencies from the satellite to the ground station. In this study of the patch array using proximity coupling techniques in this study to obtain high gain and wide of bandwidth. The structure of the antenna array design consists of four identical square patch elements and to use the concept of corporate transmission line fed power divider network uses three transformers quarter-lambda T-junction.  Bandwidth impedance matching for resonance between two patches is ¾ l antenna system for center frequency of 2.25 GHz.  The antenna is designed using the method of moments through simulation with microwave office software applications. The results of simulations and measurements obtained antenna parameters, such as: bandwidth of return loss <-10 dB above 100 MHz resonant frequency shifted to 1.75%, VSWR (1 to 2), the bandwidth of axial ratio <3 dB is 1.6% (narrowband) and the maximum directivity (gain) is 9.128 dB. Overall study results showed good performance antenna array with circular polarization properties, high gain and operates in the S band frequency micro satellite system

A Wideband Series-Fed Circularly Polarized Differential Antenna by Using Crossed Open Slot-Pairs

A novel method of designing a wideband series-fed circularly polarized (CP) differential antenna by using crossed open slot-pairs is presented in this paper. The near-field distributions and input impedance analyses show that the closely spaced open slot-pairs can radiate as the crossed dipoles and have stable radiating resistance with a compact radiator size. Besides, a wideband half-power phase shifter by using open slot is proposed and utilized to realize CP radiation. The proposed CP antenna is composed of a wide slot-pair and a narrow slot-pair. In the antenna design, the narrow slot-pair is not only excited as a radiator, but also elaborately loaded to provide wideband half-power output and quadrature phase excitation to the wide slot-pair. Both the proposed half-power phase shifter and CP antenna are illustrated by the corresponding equivalent circuits. Based on these analyses, the proposed antenna is designed, fabricated and measured. Compared to the simulated traditionally designed counterpart, 2.1 times wider axial ratio bandwidth is achieved for the proposed antenna. The measured overlapped bandwidth for axial ratio 10 dB is 1.95-3.45 GHz (55.6%). Also, the antenna gain and radiation patterns are measured, which agree well with the simulated results

A Wideband, Circularly Polarized, Directive Antenna With a Circular Reflector

A two-element, patch antenna with a single feed is presented to achieve wideband, circular polarization, and uni-directional radiation. The driven element of the antenna has a rotated, corner-truncated radiating patch to achieve circularly polarized radiation with an offset microstrip feedline in the front side. The back side of the driven element comprises a wide hexagonal slot, eight meander tips, and a parasitic patch in the center. A circular reflector is added behind the driven element to increase realized gain toward the front side direction of the driven element. A prototype of the antenna is fabricated for validation. In both simulation and measurement, the 3-dB axial ratio bandwidth is fully included in the -10-dB impedance bandwidth. In measurement, the proposed antenna has a -10-dB impedance bandwidth of 83% (1.58 GHz - 3.83 GHz), and a 3-dB axial ratio bandwidth of 49% (1.99 GHz - 3.27 GHz). Within the common band, the average realized gain is 6.1 dBic, and the peak realized gain is 8.6 dBic toward the front side direction of the antenna. The electrical size of the antenna is a kr of 1.69

Systematic design of a circularly polarized microstrip antenna using a shape super-formula and the characteristic mode theory

The characteristic mode theory gives useful insights into the physical behavior of antennas, which can be used for the design of single-feed circularly polarized antennas. For example, an antenna with any geometrical shape may be systematically modified by the characteristic mode analysis to give circular polarization. In this paper, a procedure based on the characteristic mode theory is used for the design and modification of arbitrarily shaped antennas to produce a circularly polarized radiated field at 2.45 GHz for ISM band application. By using this procedure the axial ratio of a proposed antenna has dropped to 0.05 dB without the need of employing an optimization software