Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Angle measuring instrument and composite guiding device

Abstract: PURPOSE:To obtain a composite guiding device which has a highly accurate angle measuring ability over a wide band and an ability equal to that of an active radio guiding device by arranging passive antennas so that the performance of an active antenna cannot be deteriorated and using an algorithm with which a sufficiently high angle measuring accuracy can be obtained. CONSTITUTION:Antennas for passive radio waves are constituted by annularly arranging element antennas 14-1 to 14-n on the outer periphery of the aperture 2C of an antenna for active radio waves. The phase difference between received signals of each two adjacent ones of the element antennas 14-1 to 14-n is measured (n) times and the primary solution of the phase differences is found by applying the method of least squares. Then the phase difference of received signals at (n) pieces of element antennas and (m) pieces of secondary solutions are found by applying the method of least squares at every block of (m) pieces and the secondary solution which is the closest to the primary solution is used as the final solution of the arriving angle of radio waves. Therefore, a highly accurate radio wave arriving angle containing no ambiguity is obtained.

Experiments of a polarization-controlled active antenna to enhance BAN on-body link in human dynamic channels

Abstract: This paper presents a polarization-controlled active antenna applied to BAN on-body communications. A primal objective is to achieve the enhancement of signal power, not only in downlink but also in uplink dynamic channels, between an access point mounted on the wrist and a sensor module attached to various locations on a human body. The proposed antenna is comprised of two orthogonal antennas, which can obtain the optimum transmitting and receiving signals in considerations of the cross polarization power ratio (XPR) and antenna tilt angle. A dynamic channel model to represent the geometrical relationship between two locations considering arm-swinging motion was proposed. Based on the model, a weight function was derived to control an orthogonal active antenna in an adaptive way for increasing the radiation pattern in the direction of a desired signal. Furthermore, a preliminary experiment using a 2-element polarization-controlled active antenna based on the proposed weight function has been carried out in an anechoic chamber. The results show that a high level of the received signal power can be obtained regardless of the arm-swing angle and antenna placement both in the measured data and analytical results, confirming the effectiveness of the proposed method to enhance the BAN on-body radio links has been confirmed.

A 30 GHz, HEMT, Active Antenna Structure in MMIC Technology

Abstract: A novel MMIC active antenna structure has been demonstrated by closely integrating a HEMT device and a slot antenna on opposite sides of a GaAs substrate. To our knowledge, this is the first time that such components have been integrated on the same MMIC. It is also the first time that circuit components have used both sides of an MMIC with via holes providing the through substrate connections. This active transmit antenna was developed for 30 GHz operation.

Active antenna system

Abstract: PURPOSE:To reduce the number of cables between an antenna and tuner by superposing the operating power voltage of an active circuit incorporated in the main antenna body and antenna switching control signals together and then by sending them to the main antenna body via a common transmission line. CONSTITUTION:Superposing-synthesizing circuit 5 superposes electric circuit power source +B of receiver 1 and control signals of switching control signal generating circuit 4 that generates antenna switching control signal. To cable 6, on the other hand, an electric power source varying in level with the control signal is sent out. At the antenna side, separating circuit 7 separates electric power voltage +B and the antenna switching control signal. Outputs of two antennas 8 and 9 are selectively selected by change-over circuit 10 and applied to active circuit 11. At this time, the precedent switching control signal is used for this switching. The output of active circuit 11 is led to receiving circuit 13 at the receiver side by way of coaxial cable 12.

GPS time service active antenna

Abstract: The utility model provides an anti-jamming and high-reliable GPS timing active antenna which is applied to the CDMA and the TD-SCDMA mobile communications, and is composed of a ceramic dielectric antenna, a low noise amplifier unit, a needle-type electric coupler and an antenna housing, wherein, the ceramic dielectric antenna, the low noise amplifier unit and the needle-type electric coupler are connected sequentially. Through a plurality of technical proposals, the realized technological structure which has anti-jamming efficacy, low noise, high-gain circuit and reliable needle-type electric coupler has waterproof function and highly reliable connectivity, and the whole reliability can be improved under the protection of the antenna housing which is resistant to the ultraviolet light. The design has reasonable structure and higher cost performance.