Reflective array antenna

About: Reflective array antenna is a research topic. Over the lifetime, 4366 publications have been published within this topic receiving 57884 citations.

A new method to measure radiation efficiency of terminal antennas

Abstract: This paper considers characterization of small antennas, which operate in a multipath environment, such as antennas for mobile phones and Bluetooth modules. The characterization method is based on measurements in a reverberation chamber, which is possible due to the fact that the terminals are located in a complex multipath environment, so that normal characteristics such as radiation pattern shapes are often not important. The reverberation chamber, also called a mode-stirred chamber, is known in the EMC area, and is a kind of statistic multimode chamber. The present paper reports measurements of a simple test case in an existing reverberation chamber. The test case is a dipole located at different distances from a lossy dielectric cylinder, representing human tissue. The measurements were taken in the 900 MHz-band (870-970 MHz).

Compact Metamaterial-Based UHF RFID Antennas: Deformed Omega and Split-Ring Resonator Structures

Abstract: Over the past decade, researchers have shown significant advances in the area of radio frequency identification (RFID) and metamaterials. RFID is being applied to a wide spectrum of industries and metamaterial-based antennas are beginning to perform just as well as existing larger printed antennas. This paper presents two novel metamaterial-based antennas for passive ultra-high frequency (UHF) RFID tags. It is shown that by implementing omega-like elements and split-ring resonators into the design of an antenna for an UHF RFID tag, the overall size of the antenna can be significantly reduced to dimensions of less than 0.15λ0, while preserving the performance of the antenna.

Coaxial-Fed Circular Dipole Array Antenna With Ferrite Loading for Thin Directional Borehole Radar Sonde

Abstract: In this paper, we propose a coaxial-fed dipole array antenna in a borehole with ferrite loading to achieve a thin directional borehole radar sonde (diameter of 54 mm). This radar works between about 20 and 150 MHz. When the dipole array, proposed previously, is used for the thin radar sonde, this antenna suffers from scattered waves from the centered conducting cylinder (CCC). This disturbs the estimation of the direction of arrival (DOA) below 100 MHz. To overcome the interference of the CCC, commercial ferrite cores were added to the CCC. A method-of-moment analysis showed that we may decrease the resonant frequency of the CCC to below 20 MHz, making use of the inductive characteristics of the ferrite cores. This widens the frequency bandwidth of the antenna. Field experiments in soil showed that the ferrite core-loaded CCC works reliably and confirmed that we can estimate the DOA between 20 and 150 MHz. Other measurements in rock which examined the power spectrum of a direct wave found that the ferrite cores widened the operating frequency bandwidth of the radar system.

Performance optimization of microstrip antenna array using frequency selective surfaces

Abstract: This paper presents the application of frequency selective surfaces in antenna arrays as an alternative to improve radiation parameters of the array A microstrip antenna array between two FSS was proposed for application in WLAN and LTE 4G systems Several parameters have been significantly improved, in particular the bandwidth, gain and radiation efficiency, compared with a conventional array Numerical and measured results are presented

Switchable antenna for the VHF and UHF frequency bands

Abstract: This invention concerns an antenna switchable between the VHF and UHF frequency bands. This antenna incorporates a capacitive element, disposed at a specified distance from a reflecting surface mounted on the body of the vehicle. For VHF, tuning is obtained by a fixed self-inductance in parallel and a variable self-inductance in series with the capacitive element. The latter comprises various sections which can be short-circuited by switches. For UHF, the variable self-inductance is totally short-circuited and the fixed self-inductance is disconnected by a switch; then, plates form, with the reflecting surface and the capacitative element, a "manchette" antenna. This switchable antenna can in particular be mounted on an airplane.