Abstract: An antenna element 1 is formed such that a plurality of turning parts 13, 15, 17 are formed by being turned back in zigzag in parallel to a ground conductor film 2 while extending perpendicularly thereto and the lengths of segments 12, 14, 16, 18 between the turning parts are shorter on a side of the ground conductor film 2 (a side of a feeding part 4) and increase gradually as the segments are away from the ground conductor film 2. The turning parts of the antenna element 1 are formed such that the antenna resonates at two or more frequency bands, and has a fractional bandwidth of 4% or more of its frequency in a first frequency band and a fractional bandwidth of 15% or more of its frequency in a second frequency band by adjusting the lengths L1, L2 and L3 of respective segments and the intervals d1, d2 and d3 between adjacent segments. Consequently, a wideband antenna is realized in two or more multi-frequency bands, for example 2.4 to 2.5 GHz and 5 to 6 GHz, by using a single folded antenna.

Abstract: An antenna element 1 is formed such that a plurality of turning parts 13, 15, 17 are formed by being turned back in zigzag in parallel to a ground conductor film 2 while extending perpendicularly thereto and the lengths of segments 12, 14, 16, 18 between the turning parts are shorter on a side of the ground conductor film 2 (a side of a feeding part 4) and increase gradually as the segments are away from the ground conductor film 2. The turning parts of the antenna element 1 are formed such that the antenna resonates at two or more frequency bands, and has a fractional bandwidth of 4% or more of its frequency in a first frequency band and a fractional bandwidth of 15% or more of its frequency in a second frequency band by adjusting the lengths L1, L2 and L3 of respective segments and the intervals d1, d2 and d3 between adjacent segments. Consequently, a wideband antenna is realized in two or more multi-frequency bands, for example 2.4 to 2.5 GHz and 5 to 6 GHz, by using a single folded antenna.

Abstract: At least one filter block (25, 35, 45) is formed in a thin and flat dielectric multilayer structure (21) and fixed with radiation elements (2, 3). Each filter block includes at least one of a low-pass filter, a high-pass filter and a band-eliminating filter. On the surface (one major surface) side and/or the side face of the multilayer structure, at least one radiation element (2, 3) being connected with the filter block is provided and feeding parts (28, 38, 48) for supplying signal to the radiation elements are provided on the rear surface of the multilayer structure. Consequently, the antenna and the filter block are integrated and a small surface mountable antenna with a built-in filter of a structure such that signals are not mixed each other even when signals of a plurality of frequency bands are transmitted/received can be obtained.

Abstract: A laminated dielectric block (3) is formed by laminating dielectric sheets (31) each having a conductive film formed on its one surface so as to constitute at least one filter (2). A radiation element (1) is provided so as to fix to the laminating dielectric block, wherein one electrode of the filter is electrically connected to the radiation element. The other electrode (22) of the filter is connected to a feeding terminal electrode (4) provided mounting face B (a face opposing to a circuit board) of the laminated dielectric block through a via-contact (33) and a wiring (34), not being exposed to the side face. As a result, an antenna with built-in filter of the structure where even if it is mounted on a circuit board, interference between an electronic circuit on the circuit board and the feeding terminal electrode of the antenna is prevented to improve the isolation characteristic and transmitting or receiving characteristic.

Abstract: A laminated dielectric block (3) is formed by laminating dielectric sheets (31) each having a conductive film formed on its one surface so as to constitute at least one filter (2). A radiation element (1) is provided so as to fix to the laminating dielectric block, wherein one electrode of the filter is electrically connected to the radiation element. The other electrode (22) of the filter is connected to a feeding terminal electrode (4) provided mounting face B (a face opposing to a circuit board) of the laminated dielectric block through a via-contact (33) and a wiring (34), not being exposed to the side face. As a result, an antenna with built-in filter of the structure where even if it is mounted on a circuit board, interference between an electronic circuit on the circuit board and the feeding terminal electrode of the antenna is prevented to improve the isolation characteristic and transmitting or receiving characteristic.

Abstract: An approximately rectangular plate-shaped radiation member (2) is provided and support portions (4,6) are attached to lower surface end portions adjacent to a pair of parallel shorter sides of the radiation member (2). The support portion (4) is composed of a laminated circuit member including a laminated demultiplexer and a laminated band pass filter of the reception side and the transmission side respectively connected to the laminated demultiplexer. The radiation member (2) has a power supply terminal (2c) and a ground terminal (2d) at the end portion where the support portion (4) is mounted. The power supply terminal (2c) and the ground terminal (2d) are connected to an antenna terminal (4a) and the ground terminal (4b) of the laminated circuit, respectively. The radiation member (2) has a radiation electrode (2a) where a slot (2b) is formed. The shape of the slot is set so that the radiation electrode (2a) causes resonance in a plurality of frequency bands.

Abstract: At least one filter block (25, 35, 45) is formed in a thin and flat dielectric multilayer structure (21) and fixed with radiation elements (2, 3). Each filter block includes at least one of a low-pass filter, a high-pass filter and a band-eliminating filter. On the surface (one major surface) side and/or the side face of the multilayer structure, at least one radiation element (2, 3) being connected with the filter block is provided and feeding parts (28, 38, 48) for supplying signal to the radiation elements are provided on the rear surface of the multilayer structure. Consequently, the antenna and the filter block are integrated and a small surface mountable antenna with a built-in filter of a structure such that signals are not mixed each other even when signals of a plurality of frequency bands are transmitted/received can be obtained.

Abstract: An approximately rectangular plate-shaped radiation member (2) is provided and support portions (4,6) are attached to lower surface end portions adjacent to a pair of parallel shorter sides of the radiation member (2). The support portion (4) is composed of a laminated circuit member including a laminated demultiplexer and a laminated band pass filter of the reception side and the transmission side respectively connected to the laminated demultiplexer. The radiation member (2) has a power supply terminal (2c) and a ground terminal (2d) at the end portion where the support portion (4) is mounted. The power supply terminal (2c) and the ground terminal (2d) are connected to an antenna terminal (4a) and the ground terminal (4b) of the laminated circuit, respectively. The radiation member (2) has a radiation electrode (2a) where a slot (2b) is formed. The shape of the slot is set so that the radiation electrode (2a) causes resonance in a plurality of frequency bands.

Abstract: An antenna circuit which is improved the deterioration of amplitude characteristic in a strong electric field, an antenna circuit for AM broadcasting which can surely inhibit and damp FM-band signals in the strong electric field and amplifies to output AM-band signals, and an antenna circuit for AM/FM broadcasting in which AM-band signals are not damped by means of an FM-band filter. In the first antenna circuit, the output signal of an antenna (10) is supplied to the base of a transistor Tr2 forming a current amplification type amplifier having a high-input and low-output impedance and the emitter of the transistor Tr2 is grounded through a coil L6 and connected to an FM receiver (16) through a band-pass filter (38). In the second antenna circuit for receiving AM broadcasting, an input terminal is connected to an AM amplifier circuit (36) through coils (L7) and L8 in series and to the gate G of a field effect transistor FET.

Abstract: An antenna for mounting on a vehicle which restrains damping of a signal voltage by reducing a stray capacitance of a signal path and has an improved antenna characteristic and a short physical length, and an antenna element which is suitable for an antenna for mounting on a vehicle and is flexible by using a helical coil of a large winding diameter are provided. In the antenna for mounting on a vehicle, with respect to a band signal having a short wavelength of a plurality of band signals to be transmitted/received, an antenna element is caused to resonate with a physical length shorter than ¼ of the wavelength of the band signal. A linear line portion is provided at the proximal end, and the antenna element is provided at a predetermined distance from vehicle body and a conductive member of the same electric potential as the vehicle body. The stray capacitance between the proximal end portion of the antenna element and the vehicle body is small, and a signal voltage is outputted without being damped.

Abstract: The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.