US3918062A - Receiving loop antenna system - Google Patents

Receiving loop antenna system Download PDF

Info

Publication number
US3918062A
US3918062A US491269A US49126974A US3918062A US 3918062 A US3918062 A US 3918062A US 491269 A US491269 A US 491269A US 49126974 A US49126974 A US 49126974A US 3918062 A US3918062 A US 3918062A
Authority
US
United States
Prior art keywords
circuit
loop antenna
antenna
impedance
wireless set
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US491269A
Other languages
English (en)
Inventor
Hiroshi Haruki
Yoshiyasu Hiroi
Kyohei Fujimoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Application granted granted Critical
Publication of US3918062A publication Critical patent/US3918062A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
    • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas

Definitions

  • ABSTRACT In a receiving loop antenna especially adapted for use as a built-in antenna of a portable wireless set and of the type wherein the antenna output terminals are so tapped that power matching impedance of the wireless set may be attained, a circuit having series resonant circuit characteristics and a transmission line connected in series with the circuit and having such a length that impedance matching may be obtained, which may minimize the noise at or in the proximity of the center frequency of the frequency band of the series resonant circuit; are inserted between the antenna output terminals and the input terminals of the wireless set.
  • FIG. 1 A first figure.
  • FIG. 2B PRIOR ART FIG. 2B
  • FIG. 3A Rr PRIOR ART FIG. 3A
  • the present invention relates to generally a receiving loop antenna, and more particularly a receiving loop antenna especially adapted for use as a built-in antenna of a portable or small-sized wireless set.
  • the small-sized portable wireless sets of the hand carried type, the pocket size type, or those generally carried on backs of the operators have a built-in antenna such as a quarter-wavelength whip antenna, a dipole antenna or fernte antenna.
  • a built-in antenna such as a quarter-wavelength whip antenna, a dipole antenna or fernte antenna.
  • the antenna efficiency suddenly drops because of the considerable decrease in the intensity of the electric field around the human body.
  • Theferrite antenna which is of the magnetic field type has an advantage over the whip or dipole antenna inthat the magnetic field is intensified around the human body, but it still has a defect that the loss within a ferrite core is so increased'as the operating frequency is increased.
  • the primary object of the present invention is therefore to provide an improved receiving loop antenna especially adapted for use as a built-in antenna of a portable wireless set and capable of considerably improving the signal-to-noise ratio, S/N, of the wireless set.
  • a loop antenna is provided in one wall of the wireless set, which wall is to be in a position perpendicular to human body when put in the pocket of the operator where it is influenced by the high intensity of magnetic field component provided by the human body.
  • the other wall perpendicular to the wall having the loop antenna of the wireless set case is provided with a grounding plate, and the grounding plate and the loop antenna form an asymmetrical dipole antenna, which antenna has a reasonable sensitivity to the electric field component.
  • a circuit having series resonant circuit characteristics and a transmission line are coupled with the loop antenna, and the small loop antenna characteristics and the input impedance-noise figure characteristics are combined, and the decrease of receiving range by the reduction of antenna size is complemented. Thus, the optimum noise matching is obtained.
  • the antenna output terminals are tapped on the loop antenna at the points that the impedance thereof may enable the wireless set connected thereto to give the maximum output power (the above impedance being defined as the power matching impedance hereinafter in this specificiation). Between the antenna and power matching are combined.
  • FIG. 1 is an equivalent circuit of a: prior ar tlq a tenna; .11
  • FIGS. 2B and 3B are equivalent circuits of the loop antennas shown in FIGS. 2A and 3A, respectively;
  • FIG. 4 is a circuit diagram of a loop antenna in accordance with an embodiment of the present inventibny
  • FIG. 5 is a Smith chart used for the explanation thereof;
  • FIG. 6 is a graph illustrating the improvement of the signal-to-noise ratio, S/N, attained by the present invention over the p rio'r art antenna;
  • FIG. 7 ' is a schematic perspective view illustrating the antenna system of the present invention'mounted on a portable wireless set.
  • FIGS. 8 and 9 are circuit diagrams of other embodiments of the present invention respectively.
  • FIGs. 1,2 and 3 Prior to the description of the preferred embodiment of the present invention,'some prior aItantennas will be briefly described in order to' more specifically point 1 out the defects and problems thereof which the present I invention may substantially eliminate
  • theperipheral length of a built-in loop an tenna of a compact wireless set is considerably smaller than the wavelength used 'so that it may be treated as a small loop antenna in analyses.
  • the radiation resistance R, of a small loop antenna with across sectional area A is in inverse proportion to the fourth power of the wavelength M, as shown in the following relation:
  • FIGs. 2A and 3A' are circuit idiagramsjfof int; art' Therefore, the loop antenna having such a low radiation resistance cannot be used with the wireless set because the mismatching loss becomes intolerably high.
  • a variable capacitor 2 with a capacitance C is inserted for tuning, and output terminals b and care spaced apart from each other by a distance S so as to match the impedance of the loop antenna 1 with the input impedance of the wireless set.
  • the equivalent circuit of the loop antenna 1 is shown in FIG. 23, wherein L, and L self-inductances of the sections between b and c and between a and c, respectively;
  • the impedance Z,-,, of the loop antenna 1 looking back from the terminals b and c into it is given by resonance 0 r ll] resonance
  • the inductances L, and L and the mutual inductance M may be varied by changing the tapping position of the terminal c so that the input impedance Z, may be so varied as to match with the load impedance Z, in a relatively simple manner. That is, the inductance of the loop antenna itself is utilized to match the input impedance thereof.
  • FIG. 3A In a loop antenna of the type shown in FIG. 3A, two capacitors C, and C are inserted in order to attain the impedance matching.
  • the equivalent circuit is shown in FIG. 3B.
  • the capacitors C, and C are connected in sereis for tuning, and one output terminal b is the junction between the capacitors C, and C, while the other output terminal c, the other terminal of the capacitor C
  • the input impedance Z,-, at a resonant frequency is given by n H l/( 1+ C0]2 resonance where C, and C are capacitances of the capacitors C,
  • the input impedance 2 may be changed by changing the capacitances C, and C
  • the impedance matching between the loop antenna and the wireless set may be attained in the manners described above, but when the antenna loss is considerably greater, the signal-to-noise ratio, S/N, of the wireless set must be taken into consideration. That is, the antenna for the wireless set must be so designed that not only the impedance matching may be attained but also S/N in the wireless set may become maximum.
  • the antenna impedance must be so selected that the noise figure in the input circuit of the wireless set may be minimized over a wide range of frequencies.
  • the prior art antenna whose impedance may be adjusted in the manner described above be so improved as to be connected to the input terminals of the wireless set through circuit having L-C series resonant circuit characteristics and through a transmission lines having lengths I.
  • a series resonant circuit X consisting of a capacitor C and an inductor L has its one end connected to one antenna output terminal c. and the other end d connected to one input terminal f of the wireless set through a transmission 1, line having a length l.
  • the impedances of the antenna system of the present invention are shown in the Smith chart in FIG. 5.
  • the power matching impedance for maximum power transfer is different from an impedance capable of attaining the noise matching.
  • the input impedance of the wireless set is 50 or ohms.
  • the capacitance of the capacitor 2 (see FIG. 4) is so selected that the antenna may be tuned to a frequency f,.
  • the output terminal c is so tapped that the impedance Z, of the loop antenna looking back from the terminals b and c into the loop antenna may satisfy the following relation:
  • the resistance component R that is a point at which one standing-wave -ratio circle intersects the real axis of the Smith chart, is given by
  • the resistance component of the input impedance of the loop antenna becomes Z /S at the frequencies f and f, on the curve (a) in FIG. 5.
  • the impedances are At f which is lower than the resonant frequency f, the reactance component is an inductance component but at f which is higher than the resonant frequency f, it is a capacitance component.
  • the series resonant circuit X inserted between the terminals 0 and d (or between the terminals b and c and the terminals d and e) is tuned to the resonant frequencyf
  • the impedance of the tuning circuit X is zero.
  • the tuning circuit X exhibits capacitance while at a frequency higher than the resonant frequency, it exhibits inductance.
  • the impedance is so selected as to satisfy the following relations at the resonant frequency f,, at a frequency f lower than the resonant frequency and at the frequency f higher than the resonant frequency.
  • the impedance Z looking back from the terminals f and 3 into the network is given by 1-11 ZR [(Zw j R B n j d-e B H
  • the curve (c) in FIG. 5 shows the frequency characteristic curve at Z
  • the solid curve shows the signal-to-noise ratio at the output terminals of the wireless set connected to the prior art antenna which was designed only to attain the impedance matching as described above and whose frequency characteristic curve is shown at (a) in the Smith chart in FIG. 5.
  • the broken curve line shows the S/N of the wireless set connected to the loop antenna in accordance with the present invention whose impedance characteristic is indicated by the curve (c) in the Smith chart in FIG. 5. It is apparent that the signal-to-noise ratio, S/N, is considerably improved over the wide frequency range by the antenna system in accordance with the present invention.
  • FIG. 7 shows the antenna system in accordance with the present invention attached to a portable wireless set.
  • the loop antenna 1 is attached to one side wall 5 of the wireless set which is substantially perpendicular to the body of an operator, and a grounding plate 6 is attached to another side wall 5a perpendicular to the antenna mounting side wall 5.
  • the antenna system in accordance with the present invention includes the capacitor 2, the series tuning circuit 3, and the transmission line 4, as described hereinbefore.
  • the simplest series resonant circuit may be constructed, as shown in FIGS. 4 and 7, by an impedance element and a capacitive element connected in series; however another circuit having a similar frequency characteristics as this circuit can also show similar features.
  • FIG. 8 shows the second embodiment of this invention.
  • two parallel resonant circuits which resonate at desired frequency ranges are connected between the grounding plate and the both ends of the series resonant circuit.
  • the parallel resonant circuits consist of an inductor L and a capacitor C respectively.
  • This parallel resonant circuit has a high resonant impedance in receiving frequency range; this is the reason the circuit has the same characteristics as that of L-C series resonant circuit. Outside of the receiving frequency range the impedance becomes low. This characteristic is useful for the attenuation of frequency components outside of the receiving frequency range. This is also useful for the improvement of spurious characteristics.
  • the loop antenna and the series resonant circuit are coupled through an impedance conversion transformer T. This will broaden the variable range in impedance range of series resonant circuit.
  • a receiving loop antenna system especially adapted for use as a built-in antenna which consists of a loop antenna and a grounding plate perpendicular to the loop antenna for a portable wireless set, the antenna output terminals being tapped at such points that said antenna may be matched with the input impedance of said wireless set, the improvement comprising a series-connected circuit comprising a. a circuit having series resonant circuit characteristics and tuned to the center frequency of the operating frequency range of said wireless set, and
  • said series-connected circuit being inserted between the output terminals of said antenna and the input terminals of said wireless set.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Support Of Aerials (AREA)
  • Transceivers (AREA)
  • Details Of Aerials (AREA)
  • Burglar Alarm Systems (AREA)
US491269A 1973-08-01 1974-07-24 Receiving loop antenna system Expired - Lifetime US3918062A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8714573A JPS5441192B2 (enrdf_load_stackoverflow) 1973-08-01 1973-08-01

Publications (1)

Publication Number Publication Date
US3918062A true US3918062A (en) 1975-11-04

Family

ID=13906799

Family Applications (1)

Application Number Title Priority Date Filing Date
US491269A Expired - Lifetime US3918062A (en) 1973-08-01 1974-07-24 Receiving loop antenna system

Country Status (3)

Country Link
US (1) US3918062A (enrdf_load_stackoverflow)
JP (1) JPS5441192B2 (enrdf_load_stackoverflow)
GB (1) GB1480829A (enrdf_load_stackoverflow)

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278980A (en) * 1978-03-30 1981-07-14 Nippon Gakki Seizo Kabushiki Kaisha Antenna input circuit for radio receiver
US4577195A (en) * 1982-04-20 1986-03-18 International Standard Electric Corporation Miniaturized mobile radio receiver with dipole antenna
US4920353A (en) * 1987-06-29 1990-04-24 Nec Corporation Antenna for portable radio communication apparatus
US5532705A (en) * 1993-03-17 1996-07-02 Seiko Epson Corporation Wrist-mounted-type antenna device and apparatus having the antenna device
US5589840A (en) * 1991-11-05 1996-12-31 Seiko Epson Corporation Wrist-type wireless instrument and antenna apparatus
US5673054A (en) * 1991-05-09 1997-09-30 Seiko Epson Corporation Antenna and miniature portable wireless transceiver
US5757326A (en) * 1993-03-29 1998-05-26 Seiko Epson Corporation Slot antenna device and wireless apparatus employing the antenna device
US5767813A (en) * 1993-05-27 1998-06-16 Raytheon Ti Systems, Inc. Efficient electrically small loop antenna with a planar base element
US5946610A (en) * 1994-10-04 1999-08-31 Seiko Epson Corporation Portable radio apparatus having a slot antenna
EP0898255A3 (en) * 1997-08-22 1999-12-22 Uni Electronics Industry Co., Ltd. A tag for theft prevention
US6271796B1 (en) * 1998-01-30 2001-08-07 Matsushita Electric Industrial Co., Ltd. Built-in antenna for radio communication terminals
US20040135726A1 (en) * 2001-05-24 2004-07-15 Adi Shamir Method for designing a small antenna matched to an input impedance, and small antennas designed according to the method
US6930260B2 (en) 2001-02-28 2005-08-16 Vip Investments Ltd. Switch matrix
EP1689021A1 (en) * 2005-02-07 2006-08-09 Sony Ericsson Mobile Communications AB In-built FM antenna
US20070080869A1 (en) * 2005-10-12 2007-04-12 Benq Corporation Antenna structure on circuit board
US7307542B1 (en) 2003-09-03 2007-12-11 Vantage Controls, Inc. System and method for commissioning addressable lighting systems
US7394451B1 (en) 2003-09-03 2008-07-01 Vantage Controls, Inc. Backlit display with motion sensor
WO2008109489A3 (en) * 2007-03-02 2008-10-30 Nigelpower Llc Wireless power apparatus and methods
US20090072627A1 (en) * 2007-03-02 2009-03-19 Nigelpower, Llc Maximizing Power Yield from Wireless Power Magnetic Resonators
US20090072628A1 (en) * 2007-09-13 2009-03-19 Nigel Power, Llc Antennas for Wireless Power applications
US20100124883A1 (en) * 2008-11-17 2010-05-20 Zhiqi Hu Integrated air loop antenna and transformer antenna assembly
US7755506B1 (en) 2003-09-03 2010-07-13 Legrand Home Systems, Inc. Automation and theater control system
US7778262B2 (en) 2005-09-07 2010-08-17 Vantage Controls, Inc. Radio frequency multiple protocol bridge
US8373514B2 (en) 2007-10-11 2013-02-12 Qualcomm Incorporated Wireless power transfer using magneto mechanical systems
US8378523B2 (en) 2007-03-02 2013-02-19 Qualcomm Incorporated Transmitters and receivers for wireless energy transfer
US8447234B2 (en) 2006-01-18 2013-05-21 Qualcomm Incorporated Method and system for powering an electronic device via a wireless link
US8482157B2 (en) 2007-03-02 2013-07-09 Qualcomm Incorporated Increasing the Q factor of a resonator
US8629576B2 (en) 2008-03-28 2014-01-14 Qualcomm Incorporated Tuning and gain control in electro-magnetic power systems
US9124120B2 (en) 2007-06-11 2015-09-01 Qualcomm Incorporated Wireless power system and proximity effects
US9130602B2 (en) 2006-01-18 2015-09-08 Qualcomm Incorporated Method and apparatus for delivering energy to an electrical or electronic device via a wireless link
US20160261022A1 (en) * 2015-03-06 2016-09-08 Apple Inc. Electronic Device with Isolated Cavity Antennas
US9601267B2 (en) 2013-07-03 2017-03-21 Qualcomm Incorporated Wireless power transmitter with a plurality of magnetic oscillators
US9735822B1 (en) * 2014-09-16 2017-08-15 Amazon Technologies, Inc. Low specific absorption rate dual-band antenna structure

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52156427U (enrdf_load_stackoverflow) * 1976-05-21 1977-11-28
US4380011A (en) 1980-11-25 1983-04-12 Rca Corporation Loop antenna arrangement for inclusion in a television receiver
GB2100063B (en) * 1981-06-05 1985-03-13 Tokyo Shibaura Electric Co Antenna

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736591A (en) * 1970-10-30 1973-05-29 Motorola Inc Receiving antenna for miniature radio receiver

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736591A (en) * 1970-10-30 1973-05-29 Motorola Inc Receiving antenna for miniature radio receiver

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278980A (en) * 1978-03-30 1981-07-14 Nippon Gakki Seizo Kabushiki Kaisha Antenna input circuit for radio receiver
US4577195A (en) * 1982-04-20 1986-03-18 International Standard Electric Corporation Miniaturized mobile radio receiver with dipole antenna
US4920353A (en) * 1987-06-29 1990-04-24 Nec Corporation Antenna for portable radio communication apparatus
US5673054A (en) * 1991-05-09 1997-09-30 Seiko Epson Corporation Antenna and miniature portable wireless transceiver
US5589840A (en) * 1991-11-05 1996-12-31 Seiko Epson Corporation Wrist-type wireless instrument and antenna apparatus
US5532705A (en) * 1993-03-17 1996-07-02 Seiko Epson Corporation Wrist-mounted-type antenna device and apparatus having the antenna device
US5757326A (en) * 1993-03-29 1998-05-26 Seiko Epson Corporation Slot antenna device and wireless apparatus employing the antenna device
US5940041A (en) * 1993-03-29 1999-08-17 Seiko Epson Corporation Slot antenna device and wireless apparatus employing the antenna device
US5767813A (en) * 1993-05-27 1998-06-16 Raytheon Ti Systems, Inc. Efficient electrically small loop antenna with a planar base element
US5946610A (en) * 1994-10-04 1999-08-31 Seiko Epson Corporation Portable radio apparatus having a slot antenna
EP0898255A3 (en) * 1997-08-22 1999-12-22 Uni Electronics Industry Co., Ltd. A tag for theft prevention
US6271796B1 (en) * 1998-01-30 2001-08-07 Matsushita Electric Industrial Co., Ltd. Built-in antenna for radio communication terminals
US7414210B2 (en) 2001-02-28 2008-08-19 Vantage Controls, Inc. Button assembly with status indicator and programmable backlighting
US6930260B2 (en) 2001-02-28 2005-08-16 Vip Investments Ltd. Switch matrix
US7432463B2 (en) 2001-02-28 2008-10-07 Vantage Controls, Inc. Button assembly with status indicator and programmable backlighting
US7432460B2 (en) 2001-02-28 2008-10-07 Vantage Controls, Inc. Button assembly with status indicator and programmable backlighting
US7361853B2 (en) 2001-02-28 2008-04-22 Vantage Controls, Inc. Button assembly with status indicator and programmable backlighting
US20040135726A1 (en) * 2001-05-24 2004-07-15 Adi Shamir Method for designing a small antenna matched to an input impedance, and small antennas designed according to the method
US7057574B2 (en) * 2001-05-24 2006-06-06 Vishay Advanced Technology Ltd. Method for designing a small antenna matched to an input impedance, and small antennas designed according to the method
US7755506B1 (en) 2003-09-03 2010-07-13 Legrand Home Systems, Inc. Automation and theater control system
US7307542B1 (en) 2003-09-03 2007-12-11 Vantage Controls, Inc. System and method for commissioning addressable lighting systems
US7394451B1 (en) 2003-09-03 2008-07-01 Vantage Controls, Inc. Backlit display with motion sensor
EP1689021A1 (en) * 2005-02-07 2006-08-09 Sony Ericsson Mobile Communications AB In-built FM antenna
US7778262B2 (en) 2005-09-07 2010-08-17 Vantage Controls, Inc. Radio frequency multiple protocol bridge
US20070080869A1 (en) * 2005-10-12 2007-04-12 Benq Corporation Antenna structure on circuit board
US8447234B2 (en) 2006-01-18 2013-05-21 Qualcomm Incorporated Method and system for powering an electronic device via a wireless link
US9130602B2 (en) 2006-01-18 2015-09-08 Qualcomm Incorporated Method and apparatus for delivering energy to an electrical or electronic device via a wireless link
WO2008109489A3 (en) * 2007-03-02 2008-10-30 Nigelpower Llc Wireless power apparatus and methods
US20090072627A1 (en) * 2007-03-02 2009-03-19 Nigelpower, Llc Maximizing Power Yield from Wireless Power Magnetic Resonators
US8378523B2 (en) 2007-03-02 2013-02-19 Qualcomm Incorporated Transmitters and receivers for wireless energy transfer
US8378522B2 (en) 2007-03-02 2013-02-19 Qualcomm, Incorporated Maximizing power yield from wireless power magnetic resonators
US8482157B2 (en) 2007-03-02 2013-07-09 Qualcomm Incorporated Increasing the Q factor of a resonator
US9124120B2 (en) 2007-06-11 2015-09-01 Qualcomm Incorporated Wireless power system and proximity effects
US20090072628A1 (en) * 2007-09-13 2009-03-19 Nigel Power, Llc Antennas for Wireless Power applications
US8373514B2 (en) 2007-10-11 2013-02-12 Qualcomm Incorporated Wireless power transfer using magneto mechanical systems
US8629576B2 (en) 2008-03-28 2014-01-14 Qualcomm Incorporated Tuning and gain control in electro-magnetic power systems
US8019302B2 (en) 2008-11-17 2011-09-13 Silicon Laboratories Inc. Integrated air loop antenna and transformer antenna assembly
US20100124883A1 (en) * 2008-11-17 2010-05-20 Zhiqi Hu Integrated air loop antenna and transformer antenna assembly
US9601267B2 (en) 2013-07-03 2017-03-21 Qualcomm Incorporated Wireless power transmitter with a plurality of magnetic oscillators
US9735822B1 (en) * 2014-09-16 2017-08-15 Amazon Technologies, Inc. Low specific absorption rate dual-band antenna structure
US20160261022A1 (en) * 2015-03-06 2016-09-08 Apple Inc. Electronic Device with Isolated Cavity Antennas
US9653777B2 (en) * 2015-03-06 2017-05-16 Apple Inc. Electronic device with isolated cavity antennas

Also Published As

Publication number Publication date
JPS5034762A (enrdf_load_stackoverflow) 1975-04-03
GB1480829A (en) 1977-07-27
JPS5441192B2 (enrdf_load_stackoverflow) 1979-12-07

Similar Documents

Publication Publication Date Title
US3918062A (en) Receiving loop antenna system
US4672685A (en) Dual band antenna having separate matched inputs for each band
EP0643436B1 (en) Dual mode antenna in portable radio
JP2826433B2 (ja) アンテナ用二周波整合回路
US4723305A (en) Dual band notch antenna for portable radiotelephones
RU2143160C1 (ru) Симметрирующее устройство, устройство радиосвязи и способ конструирования антенной системы
US3728731A (en) Multi-function antenna coupler
US5515015A (en) Transceiver duplex filter utilizing saw filter
US5521607A (en) Bandswitched electrically short tactical monopole antenna system
EP0528775A1 (en) Miniature antenna
KR20090060310A (ko) 동조가능한 듀얼 밴드 안테나 시스템
US6281859B1 (en) Antenna for personal mobile communications or locating equipment
US6229489B1 (en) Retractable dual-band antenna system with parallel resonant trap
US5914691A (en) Antenna apparatus having magnetic-current-type and electric-field type antenna
US4586007A (en) Notch filter
US6259930B1 (en) Portable telephone antenna circuit with reduced susceptibility to human body and method for realizing the same
US4626862A (en) Antenna having coaxial driven element with grounded center conductor
US5065164A (en) Frequency range enchanced monopole antenna
US3942119A (en) Multiple-transmission-channel active antenna arrangement
JPH10322105A (ja) 分波器
JP2001036328A (ja) Ａｍ・ｆｍ帯受信用アンテナ
US3508272A (en) Tunable coupler for electrically short monopole antennas
CA1104713A (en) Single uhf/vhf antenna system
US5754142A (en) High efficiency antenna using parallel conductors, single conductor and supporting materials
US2390839A (en) Radio frequency coupling network