GHz Dipole Antenna Research Articles

Study on Impedance Matching of 2.4 GHz Dipole Antenna

Understanding on matching impedance between feedline and load is important in many aplication. Theoritically, matching impedance can be calculated easily if charateristic impedances both load and line is known. Practically, when we do impedance matching at certain frequency we face a problem if the impedance of the feedline and antenna are unknown. by using vector network analyzer and anechoic chamber we tried to study and to approach the impedance match through measurement of return loss, VSWR, and antenna radiation pattern. The results of studies have shown that adjusting dipole antennas to lines can be done by optimizing antenna and lines length and subsequently optimizing the use of balun. In this reasearch we optimized 2.4 GHz dipole antenna and matched it to feedline by using bazooka and balun 1 : 1. To achieve good matching, the antenna length is 0.35 λ and the feedline length multiplies 0.5 λ. The length of the bazooka and balun for the best impedance adjustment are 0.25 λ and 0.2λ.

Stretchable 5 GHz Dipole Antenna Using Silver Composite Material

A highly stretchable small-size 5 GHz dipole antenna is presented for wearable and mobile applications. A stretchable dipole antenna was fabricated using conductive polymer composite material composed of Ag flake filler and polyester binder. The dipole antenna was printed on a stretchable polyurethane substrate using a simple and inexpensive screen-printing technique. The stretchability and durability of the dipole antenna were evaluated by the stretching and cyclic stretching tests. The stretchable dipole antenna showed excellent stretchability and RF performances up to a tensile strain of 25%. The stretchable dipole antenna also exhibited outstanding mechanical durability in the 10,000-cycle cyclic stretching endurance tests.

An Aperture-Sharing Array for (3.5, 28) GHz Terminals With Steerable Beam in Millimeter-Wave Band

The integration of the sub-6 GHz and millimeter-wave (mmWave) antennas has become an important issue for the next-generation wireless communication. For the mmWave band, adaptive beam steering is required to solve the path loss and coverage range problems. In this communication, an aperture-sharing technique is developed, so that a four-unit linear 28 GHz array and a 3.5 GHz dipole antenna can be integrated and the same aperture can be shared. The SIW is utilized to enable the integration and maintain the radiation of both antennas, without mutual interference. By adopting a separate feeding network, each mmWave array unit is independently excited, so that a beam steerable in the E-plane can be synthesized in the mmWave band. A prototype is fabricated with a compact size owing to the shared aperture. The measured results show good radiation characteristics and broad 10 dB impedance bandwidth exceeding 20% in both bands. Furthermore, the mmWave beam steering is obtained with a stable gain level. The proposed dual-frequency antenna is suitable for some terminal applications in the next-generation wireless networks.

Non-destructive evaluation of moisture content of wood material at GPR frequency

GPR wave’s propagation is governed by the electromagnetic (EM) properties of a dielectric material as wood, which is affected by various material parameters such as moisture, as well as heterogeneities. This paper presents some laboratory measurements in the aim of studying the sensitivity of EM waves propagation properties to moisture variation and fibers direction in wood material. Dielectric relative permittivity was measured using resonance technique at 1.26GHz (for Spruce and Pine wood samples) and compared with GPR measurements using 1.5GHz dipole antennas for different moisture conditions.The results of this study show good relations between real/imaginary relative permittivity and moisture content of both wood samples. Moreover, due to the dependence of wood permittivity to moisture, GPR permittivity measurements in time domain present also good correlation with moisture content.