Z. H. Hu

Wide tunable dual-band reconfigurable antenna for future wireless devices

This paper presents a novel reconfigurable handset antenna for use in current and future wireless communication systems. The construction of the antenna is simple, allowing independent and versatile dual frequency and bandwidth reconfiguration, using simple external matching circuits. The antenna incorporates two metal elements which are capacitively coupled to excite resonant modes within the handset chassis. The antenna elements are located in close proximity to each other, and are connected via independent ports. The larger element is used to excite modes within the lowermost band of operation. The smaller element, on the other hand, excites resonances within the uppermost band. The matching circuit incorporates a pair of varactors and several fixed inductors. Simulations suggest that the antenna has a total tuning range of 2100 MHz (from 800 MHz to approximately 2900 MHz). In addition, the antenna is capable of operation as a penta-band cellular phone antenna. This kind of antenna is typically required to work within the GSM900, GPS1575, GSM1800, PCS1900 and UMTS2100 bands.

Wideband omni conical monopole antenna with high Q band-notched behaviour

This paper presents a wideband conical antenna incorporating a band-notched resonator. The notch band is created by using four U-shaped slots which are cut into the surface of the elliptical cone antenna. The notch band i located at 5 GHz. In comparison with previous work the main advantages of this contribution include 1) the simplicity with which the position of the notch band can be adjusted by altering the size of slot, 2) the high quality factor (high Q associated with the notch band, 3) low level of insertion loss at the centre of the notch band, and 4) omni-directiona pattern at frequencies throughout the operating band.

Novel reconfigurable dual-port UWB chassis-antenna

The current generation of mobile terminals commonly uses one or more multiband PIFA antennas. In the future it is anticipated that mobile devices will incorporate more than 20 different radio services. Some of these will be wideband radio links designed to handle large amounts of data. This creates a difficult challenge for the antenna designers. One of the more promising solutions to this problem is to use a dual-band chassis-antenna which can be tuned to operate, over a wide range of frequencies [1]. In the next generation of mobile phones, capacity and bandwidth will become critically important for UHF band (300 MHz ~ 3 GHz). Ultra-wideband (UWB) technology has shown promise for use in wireless multimedia systems. This paper presents a chassis-antenna which can operate within a narrow band or wideband modes. When operating in the narrow band mode, the antenna has a total tuning range of 2854 MHz (from 442 MHz to 2896 MHz). The return loss remains above 6 dB [2–4] throughout the tuning range. In wideband mode, the antenna can operate within one of four different but yet overlapping ultra-wideband (UWB) modes. In the UWB mode the antenna can operate from 470 MHz to 2850 MHz.

Wideband Conical Monopole Antenna with Integrated Stopband Filter

This paper presents a conical monopole antenna with two C-shaped slots to provide a frequency stopband to suppress interference. Compared to previous work reported in the literature, the antenna provides increased gain suppression to vertically polarised signals within the notch-band of up to 41.5dB in four speciflc directions. It also yields omni-directional radiation patterns at frequencies throughout the operating band, outside the rejection band. The four null directions in vertically polarised plane at the notched band frequency are explained by an analysis of simplifled equivalent current sources. The efiect of difierent length of slots has been investigated. Two methods to control the stop band directions are also discussed.

Equivalent circuit modeling of chassis-antenna with two coupling elements

In the next generation of mobile terminals, more standards and services will be rolled out (such as DVB-H. RFID, RDF, UWB, LTE etc). In the future it is anticipated that mobile devices will incorporate more than 20 different radio services [1]. For convenient portability mobile terminals need to be small. This means that the antenna should be small and whilst also supporting multiple wireless communication standards. One of the more promising solutions to this problem is to use a dual-port chassis-antenna which can be tuned to operate, over a wide range of frequencies [2–4]. In this antenna the handset chassis functions as the main radiator. Handset chassis-antennas have been used to provide coverage at cellular phone frequencies [5] and within the DVB-H band [6]. The effect of the chassis has thus become significant. Previous studies have presented an equivalent circuit for a single port chassis-antenna [5, 7–8].