The present invention relates to an antenna structure. In particular, the invention provides an antenna structure suitable for use on a printed circuit board for Wireless Local Area Network (WLAN) use, where the antenna radiates over multiple frequency bands corresponding to several WLAN frequency bands.
Wireless Local Area Network (WLAN) stations and access points operate in at least one of the several WLAN frequency bands centered about 2.4 GHz, 4.9 GHz, 5.2 GHz, 5.5 GHz, and 5.8 GHz. Typically, each frequency requires a separate quarter wavelength antenna structure. In free space, a quarter wavelength for each of 2.4 GHz (Low Band, referred to herein as LB), 5.07 GHz (High Band Lower, referred to herein as HB-L), and 5.57 GHz (High Band Upper, referred to herein as HB-U) is approximately 31 mm, 14.7 mm and 13.4 mm, respectively. A printed circuit substrate such as FR4 has a permittivity ε of 4.2 on one surface and free air on the other, so the lengths of the quarter wavelength shortens by a scaling factor of approximately
or 62% of the free space wavelength. In the prior art, each antenna structure is implemented with a separate quarter wave radiating structure implemented on a conductive pattern printed on FR4 substrate. It is desired to provide a single radiating antenna structure for use with a plurality of RF frequencies for use in a LAN.
A first object of the invention is a printed circuit antenna fed by a wideband feedline delivering to the radiating antenna multiple separate operating frequencies which the radiating antenna radiates efficiently at each separate operating frequency and presents a minimum return loss at each particular operating frequency to the feedline, the radiating frequencies including at least a Low Band (LB) frequency, High Band Lower (HB-L) frequency, and a High Band Upper (HB-U) frequency.
A second object of the invention is a printed circuit antenna formed from a two-sided circuit board having a feedline part and a radiating antenna part, the feedline part formed from conductors on an upper plane separated from an optional lower ground plane by a dielectric, the ground plane present in the feedline part and not present in the antenna part, the feedline region optionally having one or more edge-coupled ground reference structures, the radiating structure including:
A feedline region 142 comprises a feedline 102 in a first plane which is separated from a ground plane 202 by a dielectric 204. The feedline 102 is optionally edge coupled to a left ground structure 104 or a right ground structure 106, the left ground structure 104 and right ground structure 106 formed by a conductor in the first plane which is either connected directly to the ground plane 202 or is formed by a conductive region which is at the same electrical potential as the ground plane 202, such as by a close proximity of the ground structures 104, 106 and the ground plane 202. The feedline 102, left ground structure 104, and right ground structure 106 are electrical conductors all located on the first plane of a circuit board, below which is a reference ground plane 202 which serves as a reference plane for the feedline 102 and separated by a dielectric material 204 such as FR4. The feedline and associated structures thereby provide a particular feedline 102 impedance, such as 50 ohms. Beyond the extent of the feedline 102, left ground structure 104, and right ground structure 106 is a radiating antenna region 140 which contains radiating structures formed as electrically conductive segments without a ground plane 202 below.
In one embodiment of the invention, the feedline 102 transitions over the edge 144 of a ground plane 202 to the antenna region 140 which includes a first segment 108, second segment 112, and third segment 114, which form a highband-upper HB-U RF radiator for RF delivered by the feedline in this frequency range. The first segment 108 and a first stub 110 which extends from the first segment 108 are coupled through a gap region 123, and in sequence to, a lowband (LB) radiator formed by a fourth segment 122, fifth segment LB radiator 120a, fifth segment common radiator 120b, and sixth segment 118, which is terminated in a ground reference such as left ground structure 104. The LB radiator structure thereby radiates LB RF coupled from the feedline 102 and first stub 110.
A highband lower (HB-L) radiator is formed from the sixth segment 118, fifth segment common radiating structure 120b, a bridge 130, a seventh segment HB-L radiator 128a, and an eighth segment HB-L radiator 132, where the HB-L radiator receives RF energy in the HB-L frequency range from the feedline 102, which couples across gap 123, through the fourth segment 122 and fifth segment LB radiator 120a, which are capacitively coupled for the HB-L frequency. An LB inductive structure (which is inductive for LB frequencies) is coupled from the intersection of the bridge 130 and the seventh segment HB-L structure 128a to the intersection of the fifth segment LB radiator 120a and fourth segment 122, and the LB inductive structure comprises, in sequence, a seventh inductive segment 128b, a ninth segment 126, and a tenth segment 124.
When the feedline 102 is fed with a lowband (LB) frequency such as 2.46 GHz, the RF travels from the feedline 102 through first segment 108 and first stub 110, coupling through a separation gap 123 to the fourth segment 122, fifth segment LB radiating structure 120a, fifth segment common radiating structure 120b, and sixth segment common radiating structure 118, the terminus of which is ground referenced such as with left ground structure 104. At 2.4 GHz, an inductive stub is formed by the segments 124, 126, 128b, 128a, and 132. When the feedline 102 is fed with a highband lower (HB-L) frequency such as 5.07 GHz, the RF travels from the feedline 102 to the first segment 108 and stub 110, edge couples through gap 123 to fourth segment 122 and fifth segment LB radiator 120a to the HB-L radiating structure formed by the sequence of sixth segment common radiating structure 118, fifth segment common radiating structure 120b, bridge 130, seventh segment HB-L structure 128a and eighth segment HB-L radiating structure 132.
When the feedline 102 is fed with a highband upper (HB-U) frequency such as 5.57 GHz, the RF travels from the feedline 102 to the first segment 108, second segment 112, and third segment 114.
In the embodiment shown in
In one embodiment of the invention shown in
Alternatively, the frequency range for each of HB-U, HB-L, and LB may be specified in return loss measured at the feedline.
At the junction of fifth segment LB radiating segment 120a and fifth segment common radiating structure 120b is bridge 130, which couples HB-L RF to HB-L radiators formed by the sequence of eighth segment radiator 132, seventh segment HB-L 128a, bridge 130, fifth segment common radiating structure 120b, and sixth segment common radiating structure 118.
Bridge 130 is also connected to seventh segment 128b, ninth segment 126, and tenth segment 124 connected to the junction of fifth segment 120a LB radiator and fourth segment 122. Seventh segment 128b, ninth segment 126, and tenth segment 124 operate together to form an inductive stub for LB coupled to fourth segment 122, directing energy to the LB radiating structure formed by 122, 120a, 120b, and 118. Bridge 130 also forms the HB-L resonant structure which couples HB-L RF energy from first segment 108 across gap 123 to fourth segment 122, and to the HB-L resonant structure formed by fifth segment common radiator 120b, sixth segment 118, bridge 130, seventh segment 128a, and eighth segment 132.
In one embodiment, the tri-band radiator is formed from segment structures which perform functions as described below:
The structures of
For highband upper (HB-U) RF such as 5.57 GHz, feedline 102 couples RF to the HB-U radiating elements comprising first segment 108, second segment 112, and third segment 114. Reference segment 116 provides edge coupling to the HB-U radiating elements and increases the effective bandwidth of the HB-U radiating elements. The HB-U elements 108, 112, and 114 act as a quarter wave radiator at 5.57 Ghz.
For a lowband (LB) radiation frequency such as 2.46 GHz, the physical dimensions of the conductor segments are selected to provide coupling of LB RF from first segment 108 and first stub 110 to the LB RF radiating structure comprising fourth segment 122, fifth segment LB radiating structure 120a, fifth segment common radiating structure 120b, and sixth segment common radiating structure 118. For the LB frequency, the seventh segment 128b, ninth segment 126, and tenth segment 124 act as an inductive stub, shortening the length of LB radiation structure 122, 120a, 120b, 118 from its natural quarter wavelength at 2.46 Ghz.
For highband lower (HB-L) RF such as 5.07 GHz, the physical dimensions of the conductors are selected to provide a radiating structure comprising, in sequence, sixth segment common radiation structure 118, fifth segment common radiation structure 120b, bridge 130, seventh segment 128a, and eighth segment 132, and these elements together form a half wavelength radiator at the HB-L frequency.
Without limitation of the scope of the invention, a series of dimensions is offered as an example, the design of which provides the return loss plot shown in
In the example embodiment of the invention shown in
A HB-U radiating structure is formed by first segment 502 coupled to second segment 504. The other structures third segment 510, fourth segment 512, fifth segment 514, sixth segment 516, and seventh segment 518 have inductive coupling at HB-U radiating frequencies, and have minimal effect for HB-U frequencies.
A LB radiating structure is formed by third segment 510, fourth segment 512, and fifth segment 514, which is terminated in left ground structure 104. For LB radiation, first segment 502 acts primarily to couple RF energy across gap 508 to the LB RF radiating structure, and an inductive structure for LB RF is formed by sixth segment 516 and seventh segment 518.
The HB-L radiating structure is formed by fourth segment 512, sixth segment 516, and seventh segment 518. HB-L RF is coupled to the HB-L RF structure through first segment 502 and gap 508 to third segment 510, and also through second segment 504 to seventh segment 518 to the HB-L radiating structure 512, 516 and 518.
Other arrangements of the HB-U, LB, and HB-L radiators are possible, but the example embodiment of
The proceeding has been a description of the preferred embodiments of the invention. It will be appreciated that deviations and modifications can be made without departing from the scope of the invention. In particular, the following modifications may be made individually, or in combination:
Any of the above modifications may be made through compensation of the lengths or dimensions of other structures to maintain the frequency characteristics desired. Dimensions which are provided for each of the segments of the corresponding embodiments are for exemplar use with the particular frequency given, and it is understood that any dimensioned segment of the previously described radiation structures may be modified+/−20 percent and still be usable for the specified WLAN frequencies. The term “substantially” with regard to dimensions is understood to mean+/−20 percent variation, and the term “substantially” with regard to parallel or perpendicular is understood to mean within 10 degrees of true parallel or perpendicular, respectively. The term “substantially” with respect to a particular frequency is understood to mean within +/−20 percent of the particular frequency. The scope of the invention is defined by the claims which follow.
The present application is a divisional application of U.S. patent application Ser. No. 14/176,127 filed Feb. 9, 2014.
Number | Name | Date | Kind |
---|---|---|---|
7403160 | Chiang et al. | Jul 2008 | B2 |
7586452 | Li et al. | Sep 2009 | B2 |
7742006 | Villarroel et al. | Jun 2010 | B2 |
8284115 | Nysen et al. | Oct 2012 | B2 |
8344959 | Autti et al. | Jan 2013 | B2 |
8436774 | Wong | May 2013 | B2 |
8587491 | Badaruzzaman et al. | Nov 2013 | B2 |
8754817 | Kuo | Jun 2014 | B1 |
20050195119 | Gaucher | Sep 2005 | A1 |
20060145923 | Autti | Jul 2006 | A1 |
20080180333 | Martiskainen | Jul 2008 | A1 |
20100123640 | Hui | May 2010 | A1 |
20120194390 | Endo | Aug 2012 | A1 |
20120262343 | Radojkovic | Oct 2012 | A1 |
20120313830 | Lee | Dec 2012 | A1 |
20140266936 | Emmanuel | Sep 2014 | A1 |
Entry |
---|
Xiao Lei Sun, Dual-Band Antenna with Compact Radiator for 2.4/5.2/5.8 GHz WLAN Applications, IEEE Transactions on Antennas and Propagation, vol. 60, No. 12, Dec. 2012. |
Sun, Liu, Cheung, Yuk, “Dual-Band Antenna With Compact Radiator for 2.4/5.2/5.8 GHz WLAN Applications”. |
Number | Date | Country | |
---|---|---|---|
Parent | 14176127 | Feb 2014 | US |
Child | 15188450 | US |