Abstract:
A personal communications apparatus, for example a cellular telephone handset, has an antenna diversity arrangement comprising first and second antennas (102A, 102B) arranged with their polarisation axes slanted with respect to the median plane of the handset body (218). By a suitable choice of inclination angles one of the antennas can be arranged to be substantially vertical in use, whether by right or left handed users, thereby improving received signal strength from a vertically polarised base station. The arrangement also enhances diversity operation, since the correlation between the field strengths received by the antennas is reduced by their relative orientation. When the apparatus is used in a system employing a Code Division Multiple Access (CDMA) techniques, the apparatus preferably includes a 2D Rake receiver for mitigating the effects of multipath fading and interference.
Abstract:
A dual band patch antenna (700) comprises a conventional patch conductor (106) having a resonant circuit (702, 704) connected between the patch conductor and a ground conductor (102). The resonant circuit (702, 704) modifies the behavior of the antenna (700) in the vicinity of its resonant frequency, thereby providing a dual band antenna in which both bands can be used simultaneously. The total radiating bandwidth of the dual band antenna is significantly greater than that of an equivalent antenna having no resonant circuits. Additional resonant circuits can be employed to provide a multi-band antenna.
Abstract:
A cheaper to produce, smaller and easy to drive adaptive antenna module is presented. The module comprises a signal path, an antenna, and a tuning circuit with two variable impedance elements. The tuning circuit operates over a restricted range of impedances and maintains the series resonance characteristic of the antenna.
Abstract:
A tuneable capacitor arrangement for RF use has two series coupled MEMS variable capacitors (C1,C2;C4,C5,C6,C7), varied according to a control signal. The series coupling enables the capacitor to withstand a higher voltage since this is shared by the individual capacitors in a series coupled arrangement. An increase in size of electrodes for each capacitor is compensated by a reduction in size of the springs supporting movable electrodes. These springs can have a larger stiffness value since the capacitance is larger. This means shorter springs, which can also result in a reduction in problems of stiction, resistance, and slow switching. The capacitances have a fixed and a movable electrode, with the RF signal coupled to the fixed electrode to avoid the springs needing to carry an RF signal. This can reduce the problems of inductance and resistance in the springs.
Abstract:
A wireless terminal includes a housing (10) containing a substrate (12) having a ground plane, RF components mounted on the substrate, a PIFA (Planar Inverted-F Antenna) (16) carried by the substrate and coupled electrically to the RF components for transmitting and receiving signals and a notch antenna (14) in the substrate for receiving signals in a frequency band at least partially overlapping the transmission bandwidth of some of the signals transmitted by the PIFA. The notch antenna is de-activated when the PIFA (16) is being used for transmitting a signal lying within the said transmission bandwidth.
Abstract:
A method of offsetting a mismatch due to user interaction when handling a portable wireless terminal in which antenna matching is changed from inductive matching to capacitive matching in response to a reactance change exceeding a threshold level and vice versa when an opposite change is detected. An antenna interface module (44) is coupled between a RF output or input stage (25 or 33) and an antenna (48 or 50). The antenna interface module includes first and second switches (SW1/1, SW1/2 or SW2/1, SW2/2), a first matching circuit including an inductive reactance (68 or 96) coupled between the power amplifier and the first switch and a second matching circuit including a capacitive reactance (68 or 92) is coupled between the RF output or input stage and the second switch (SW1/1 or SW2/1). A reactance threshold detector (54 or 56) determines if the reactance change traverses a predetermined threshold value and causes the first and second switches to be actuated so that the matching changes from inductive to capacitive or vice versa.
Abstract:
A wireless terminal comprises a ground conductor (1102) and a transceiver coupled to an antenna feed, the antenna feed being coupled directly to the ground conductor (1102). In one embodiment the ground conductor is a conducting case (1102). The coupling may be via a parallel plate capacitor (504) formed by a plate (506) and a surface (1108) of the case (1102). The case (1102) acts as an efficient, wideband radiator, eliminating the need for a separate antenna. In a modification of this embodiment a slot (1112) is provided to increase the resistance of the case (1102) as seen by the transceiver, thereby increasing the radiating bandwidth of the terminal.
Abstract:
Abstract: A planar antenna assembly (AA) for an RF communication module, comprises i) a conductive plate having a first linear side of a first length and in which is defined a first notch (N1) of a first width and a first electrical length, equal to a quarter of a wavelength corresponding to a chosen frequency of a working frequency band, and comprises a straight part having an open end (OE1) found on the first side, and a shortened end (SE1), and ii) a first feed line (FL1) defined above the conductive plate and across the first notch (N1) and arranged to be coupled to this first notch (N1) to enable wideband operation. The first length of the first side is equal to half this wavelength. Moreover, the first notch open end (OE1) is present approximately in the middle of the first side. Moreover, the first width of the first notch (N1) is chosen such that the proportion of energy stored in the fields associated with the first notch (N1) is low compared with the result of the chosen frequency times the power radiated from the currents propagating around the first notch.
Abstract:
An antenna arrangement includes aground conductor (302) incorporating two slots (304a,304b) having an electrically small separation and connections (308a,308b) for coupling a transceiver to each slot to enable the ground conductor to function as two substantially independent antennas. Such a device enables efficient diversity performance to be obtained from small volume. The ground conductor, slots and transceiver are integrated in a module (206) adapted for connection to a further ground conductor which provides the majority of the antenna area. The further conductor would typically be a printed circuit board ground plane or mobile phone handset. Matching and broadbanding circuitry may conveniently be incorporated in the module. By varying the area of the connections between the module and the further ground conductor, the resonant frequencies of the slots can be modified.
Abstract:
In an ad-hoc radio communication system comprising a plurality of stations (100) formed into at least one network (102a,102b), each station (100) is assigned a rank representative of its suitability for performing the role of master station in a network (102a). The rank may for example be assessed depending on the performance of the station's antenna (204) or its access to mains power. It is arranged that the station (100) having the highest rank in a network (102a,102b) performs the role of master for that network, thereby improving the efficiency of communication in the network.