A 77GHz on-chip microstrip patch antenna with suppressed surface wave using EBG substrate

This paper presents the design of a patch antenna with suppressed surface waves by means of applying an electromagnetic band-gap structure. Establishing th e antenna on high dielectric substrate such as Silicon makes it possible to integrate the antenna with RFIC active component and circuitry. However, the performance (gain and radiation pattern) of antenna will be degraded due to the presence of surface waves on a thick dielectric substrate. It is possible to des ign an engineered substrate that filters out the surface wave around the frequency of interest. Moreover, having high dielectric substrate will localize EM wave to substrate and hence reduce antenna gain. For this problem, available silicon etching technology is used to remove the substrate right under the patch and have a locally low dielectric constant substrate underneath the antenn a. Proposed microstrip antenna resonates at 77GHz with 7dB realized gain which can be used in array for Automotive Radar purposes. Simulation results show great improvement in radiation pattern and 3dB increase in antenna's broadside gain in comparison with antenna on normal substrate

Phased array antenna element for automotive radar application

In this thesis work, a design of reliable antenna front-end for W band automotive radar is studied and the problems and considerations associated with phased array antenna design at W-band are addressed. Proposed phased array antenna consists of on chip patch antenna which has the advantages of being integrated by the active circuitry. A sample of patch antenna and patch array are designed and fabricated to be tested for their functionality. Printing antenna on Silicon substrate is a compact and cost-effective approach. However, antenna on Silicon will have poor gain and will also suffer from surface wave (SW) excitation. The reason for this is Silicon high dielectric constant and loss. Surface wave can be easily excited on high dielectric constant substrate which results in gain drop and distortion in radiation pattern. To avoid substrate loss, available back etching in foundry process is used to remove the silicon under the radiating antenna and improve the gain. To kill the surface wave, a type of engineered material- called Electromagnetic Band-Gap (EBG)- is designed to filter the SW around the antenna's frequency of operation. To test the fabricated antenna, a measurement setup is implemented to do refection coefficient and radiation pattern measurement. Measured S parameters show that there is frequency shift in response of measured antenna with respect to the simulated one. This shift can be attributed to uncertainty about the dielectric constant of Silicon at W-band. To find the exact value of Silicon dielectric constant, a measurement setup based on free space method is devised to determine the exact value of the silicon dielectric constant at W-Band frequency range

The Effect of Mulch, Pruning and Plant Density on Some Traits of Related to Production in Pepino

Pepino (Solanum muricatum) a new vegetable crops, is from Solanaceae family and cultivated as annual crops. In order to investigate the effects of mulch, pruning and plant density on some traits of related to production in Pepino, an experiment was conducted based on a randomized complete design with five replications at the Ferdowsi University of Mashhad greenhouse during 2009-2010. Traits such as leaf area, number of panicles per plant, number of fruits per plant, fruit length, fruit diameter and fruit weight. Treatment included: 3 levels of mulch (rice straw mulch, wood chips mulch and control), 3 levels of prune (two peduncular, 3 peduncular and controls) and 2 levels of plant density (3.3 and 4.3 plants per m2). The results indicated that the effect of mulch in all of the traits was significant (p≤0.01). Wood chips mulch in all of the traits was better than rice straw and control. Pruning was significant in all of the traits. The number of panicles and the number of fruits per plant were higher in tree peduncular but increasing the number of fruits was associated with a reduction in size. Interaction between mulch and pruning was significant in all of the traits. Plant density applied had significant effects on traits related to fruit

W-band silicon dielectric measurement

In this paper, a free space based method for measurement of silicon dielectric constant is presented at W band frequencies. The dielectric constant of silicon is calculated using measured phase information of the transmitted signal (S21) through Silicon sheet of 500um thickness. Measured dielectric constant for silicon wafer has numerous fluctuations which come from multiple reflection and diffraction effect due to sharp edges

Instability and phase transitions of a rotating black hole in the presence of perfect fluid dark matter

In this paper, we study the thermodynamic features of a rotating black hole surrounded by perfect fluid dark matter. We analyze the critical behavior of the black hole by considering the known relationship between pressure and cosmological constant. We show that the black hole admits a first order phase transition and, both rotation and perfect fluid dark matter parameters have a significant impact on the critical quantities. We also introduce a new ad hoc pressure related to the perfect fluid dark matter and find a first order van der Waals like phase transition. In addition, using the sixth order WKB method, we investigate the massless scalar quasinormal modes (QNMs) for the static spherically symmetric black hole surrounded by dark matter. Using the finite difference scheme, the dynamical evolution of the QNMs is also discussed for different values of angular momentum and overtone parameters.Comment: 13 pages, 14 figures, version accepted for publication in Eur. Phys. J.