Researches On Broadband And Compact Antenna And Array Techniques

With the rapid development of modern wireless communication technology, largescale integrated circuit and space technology, there has been a trend that all kinds ofelectronic devices are miniaturized. However, antenna plays a key role in the front endof the communication equipment, whose performance is crucial for the communicationquality. Therefore, it is very important to develop various miniaturized antennas,especially broadband and compact antennas and arrays in HF,VHF/UHF bands, toadapt the miniaturized equipments.The key techniques such as antenna miniaturization, broadband, high gain and soon have been studied theoretically and experimentally using Hilbert curves'space-filling properties and meta-material left-handed properties in HF, VHF/UHFantennas and arrays. Some designs have been proposed and the correspondingprototypes have been made.The main contents and results are as follows:1. The progress in broadband and miniaturization for antenna and array isreviewed and analyzed. It shows that miniaturization for antenna, especiallyminiaturization for HF, VHF and UHF antenna is a bottleneck in the presentdevelopment of wireless communication. Althrough remarkable progress has been madewithin the last few decades, but a lot of questions and key techniques have not beensolved in this field.2. Miniaturization technique for Hilbert antenna is studied. Firstly, the conceptionof fractal and its application in antenna are elaborated and discussed. Moreover, theantennas with lower order space-filling curves structures are analyzed in detail. Then,combined with Hilbert curve' space-filling technique and embedded-matching techniqueorganically, a compact antenna is proposed using first-order Hilbert space-filling curvestechnique according to the actual condition. The embedded-matching network and thelumped loading matching network are optimized using the genetic algorithm. Thebroadband in all of the bands is designed using self-structuring technique and theproperties of the antenna are tested. Finally, a broadband and compact antenna with integrated dipole is proposed in order to make up the fault of Hilbert antenna.3. ESA (Electrically Small Antenna) based on artificially electromagneticmeta-materials is studied. Firstly, the physical properties of the meta-material areanalyzed. The interaction mechanism between the spatial match layer and ESA and theequivalent-circuit model are studied. A novel broadband, omni directional, high gainsmart antenna is studied and designed to meet with the requirement of application in theproject. Then, researches are focused based on broadband and compact antenna basedon composite right/left-handed trans-mission lines. Properties of the left-handedtransmission line and right/left-handed transmission line based on dipoles are depictedin detail. The physical properties and the equivalent realization of left-handed andright/left-handed transmission line structures are analyzed. Finally, a novel structure ofbroadband ESA is designed. A novel aperiodic broadband and compact antenna isdesigned.4. Combined Hilbert curves' space-filling technique with compositeright/left-handed transmission line, an array model based on the first-order Hilbertdipoles is analyzed theoretically. The feed-network is analyzed and designed using thephase characteristic of the composite right/left-handed transmission line. Then, aWilkinson power divider is designed based on composite right/left-handed transmissionline and the matching network is analyzed and optimized using ADS software.Finally, a novel broadband and compact structure is designed to meet the requirement ofESA (Electrically Small Antenna) in the project.5. Conclusion and prospect.