Patent Application
20150145740
1. Field of the Invention
The present invention relates to antenna systems generally and, more specifically, to a combined frequency multiplier and slot antenna.
2. Description of the Related Art
Very short range communication systems are being touted for low power, secure communications, particularly in battery operated portable equipment. Previous attempts with near-field communications have been less than satisfactory due to the relatively large wire coil or loop antennas that are required for operation at typical industrial/scientific/manufacturing (ISM) frequency allocations, e.g., 13.56 MHz. Moreover, these relatively low frequencies cannot communicate at the multi-megabit datarates needed for many applications in use today, e.g., mobile-to-mobile file transfers. Bluetooth transceivers are low power and can handle high-speed data transfer but they are subject to eavesdropping due to the 10+ meter communications distances that Bluetooth transceivers can communicate.
One technique for providing very short-range, high datarate communication is to transmit at frequencies that have a high enviromental absorption rate and operate at low power. For example, the 60/61 GHz ISM band is subject to relatively high levels of absorption (several dB/km) by molecular oxygen. Thus, using a low power transmitter at these frequencies, a maximum communication distance of less than a few meters is possible with a low probability of intercept by an eavesdropping receiver that is more than this distance from the transmitter.
Generating any significant power at these frequencies is problematic with low cost silicon-based complementary metal-oxide-semiconductor (CMOS) processes. Higher performance silicon-germanium (SiGe) and gallium arsenide (GaAs) semiconductor technologies are typically unable to operate at frequencies greater than 20 or 30 GHz. Indium phosphide transistors are capable of doing so but fabricating these devices is expensive and integrating them into silicon-based devices is difficult. Thus, it is desirable to provide an expensive, low power transmitter operable in the 60/61 GHz band that utilizes silicon-based devices such as low cost CMOS devices.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The drawings are not to scale.
In one embodiment of the invention, a conducting substrate and a non-linear device are provided. The substrate, having a first major surface and a second major surface, has a slot formed therein, the slot having a major axis and a minor axis. The non-linear device has two terminals and those terminals are coupled between opposing edges of the slot on the first major surface and aligned with the minor axis.
Other embodiments of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which like reference numerals identify similar or identical elements.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term “implementation”.
It should be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps might be included in such methods, and certain steps might be omitted or combined, in methods consistent with various embodiments of the present invention.
Also for purposes of this description, the terms “couple”, “coupling”, “coupled”, “connect”, “connecting”, or “connected” refer to any manner known in the art or later developed in which energy is allowed to transfer between two or more elements, and the interposition of one or more additional elements is contemplated, although not required. Conversely, the terms “directly coupled”, “directly connected”, etc., imply the absence of such additional elements. Signals and corresponding nodes or ports might be referred to by the same name and are interchangeable for purposes here. The term “or” should be interpreted as inclusive unless stated otherwise.
The present invention will be described herein in the context of illustrative embodiments of an slot antenna with an integrated frequency multiplier adapted for use in a portable apparatus, such as a wireless terminal, or the like. It is to be appreciated, however, that the invention is not limited to the specific apparatus and methods illustratively shown and described herein.
The non-linear device 108 is positioned along the slot 102 to achieve the desired output power from the slot antenna. Generally, the greatest output will occur when the device 108 is displaced from center line or midpoint 110 of the slot along its major axis, the amount of displacement or offset 112 might be dependent on the characteristics of the device 108 and the length of the slot 102 along the minor axis 106. In one embodiment, the non-linear device 108 has two leads or terminals, both of which are electrically connected (through bonding, soldering, welding, etc.) to opposite sides of the slot as shown, here on opposite sides of the slot 102 and aligned with the minor axis 106 of the slot 102. Thus, the length of the slot 102 along its minor axis is approximately equal to the length of the device 108 but might be larger or smaller. In an alternative embodiment discussed in more detail below in connection with
The non-linear device 108 is chosen to generate radio frequency signals at multiples of the RF signal applied to it. Some devices, such as a gallium arsenide or indium phosphide junction diode or Schottky diode (sometimes referred to as a metal-semiconductor diode or hot-carrier diode) might be relatively efficient in generating even order harmonic signal, whereas anti-parallel diodes (i.e., two or more diodes connected in parallel with cathodes connected to anodes) might be relatively efficient in generating an odd order harmonic signal. Alternatively, one or more PIN diodes (diodes formed from p-type and n-type semiconductor with an undoped (insulating) semiconductor region therebetween) or one or more step-recovery diodes might be used for the non-linear device 108 depending upon the frequency of use, the desired output power, and the amount of frequency multiplication required. Alternatively, the non-linear device 108 might be implemented as an integrated frequency multiplier, such as a microwave monolithic integrated circuit (MMIC) having an active frequency multiplier therein, e.g., a synchronous oscillator or a BGX7101 available from NXP Semiconductors of San Jose, Calif.
A cross-section of the slot antenna and frequency multiplier along the line A-A of
The layer 204, over another major surface of the substrate 100, has terminals 206 therein that are used to electrically connect leads of the device 108 to the sides of the slot 102 as discussed above. As will be illustrated below in connection with
A transmission line 208, shown here as having two conductors, couples a signal source 210 to the device 108. The signal source 210 provides an RF signal having a frequency that is an integral fraction of a desired frequency of the radio frequency signal to be radiated by the slot 102. The device 108 receives the RF signal from the source 210 and multiplies the frequency of the RF signal to the desired frequency for the slot 102 to radiate. For example, if the desired frequency is 60 GHz, then the frequency from the source 210 might be 20 GHz or 30 GHz depending on the amount of frequency multiplication provided by the device 108. In one example, the slot 102 has a length along its major axis 104 of approximately a half wavelength (λ/2) or longer of a RF signal being multiplied by the device 108, and approximately an odd multiple of half wavelength (λO/2) of the RF signal generated by the device 108 for radiation by slot 102, i.e., N(λO/2), where N=1, 3, 5, etc. For example and for this embodiment, having the device 108 operate as a frequency tripler (e.g., 20 GHz in, 60 GHz out, making λ1=3λO) results in the length of the slot to be N(λO/2), where N=3, 5, etc.
The signal source 210 might be a implemented on an integrated circuit, such as an IEEE 802.11-compliant device, or other semiconductor device capable of providing an RF signal with sufficient power at the subharmonic of the desired frequency. With an integrated circuit signal source 210, the transmission line 208 might be a strip-line transmission line as known in the art or might simply be two or more bond wires from the integrated circuit to the terminals 206.
A conductive shield 212, such as a plate or an open-ended box covering at least the slot 102 and device 108, might be placed behind layer 204 to enhance radiation from the slot in direction of the layer 202 into free space and to protect any circuitry behind the shield from RF radiation. Preferably, the conductive shield is constructed of any suitable electromagnetic shielding material.
In one embodiment, the signal source 210 (
While embodiments have been described with respect to circuit functions, the embodiments of the present invention are not so limited. Possible implementations, either as a stand-alone antenna/frequency multiplier or embedded with other circuit functions, may be embodied in or part of a single product, such as a wireless terminal, or part of a larger system, such as part of a communication system infrasture, etc. but are not limited thereto. Such embodiments might be employed in conjunction with, for example, a digital signal processor, microcontroller, field-programmable gate array, application-specific integrated circuit, radio transceiver, frequency synthesizer, or general-purpose computer. It is understood that embodiments of the invention are not limited to the described embodiments, and that various other embodiments within the scope of the following claims will be apparent to those skilled in the art.
It is understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of this invention may be made by those skilled in the art without departing from the scope of the invention as expressed in the following claims.
This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/908,914, filed on 26 Nov. 2013, the teachings of which are incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61908914 | Nov 2013 | US |
