Patent Publication Number: US-11641051-B2

Title: Controllable electrical outlet having a resonant loop antenna

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Non-Provisional patent application Ser. No. 16/713,097 filed on Dec. 13, 2019; which is a continuation of U.S. Non-Provisional patent application Ser. No. 15/496,659, filed on Apr. 25, 2017, now U.S. Pat. No. 10,535,996, issued Jan. 13, 2020; which claims the benefit of U.S. Provisional Patent Application No. 62/327,163, filed Apr. 25, 2016, the entire disclosures of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     Many consumers reduce the total cost of electrical energy by reducing the total energy usages of electrical loads, such as lighting loads. For example, lighting loads are often controlled in response to occupancy and vacancy sensors, which detect occupancy and/or vacancy conditions in a space, to save energy. Typically, the lighting loads are turned on when the space is occupied and turned off when the space is unoccupied. In addition, consumers are becoming more sensitive to the amount of energy consumed by electrical loads, such as plug-in electrical loads that are plugged into electrical receptacles. Such plug-in electrical loads may still consume energy to maintain a standby mode when “turned off” and are often referred to as “vampire” loads. 
     Some standards (such as ASHRAE 90.1 and California Title 24) are now requiring that many electrical outlets installed in new construction or major renovations must be controlled (e.g., switched) to provide energy savings. For example, the electrical outlets may be controlled in response to a timeclock and/or an occupancy or vacancy sensor. Such electrical outlets may be coupled to a communication link (e.g., a wired or wireless digital communication link) and may be configured to receive digital messages including commands for controlling the plug-in electrical loads (e.g., in response to the timeclock and/or the occupancy or vacancy sensor). 
     SUMMARY 
     As described herein, a controllable electrical outlet for use in a load control system adapted to receive power from a power source may comprise a resonant loop antenna for receiving a radio-frequency (RF) signal. The resonant loop antenna may comprise a feed loop electrically coupled to an RF communication circuit and a main loop magnetically coupled to the feed loop. The controllable electrical outlet may comprise one or more electrical receptacles configured to receive a plug of a plug-in electrical load and an electrical connection configured to be electrically coupled to the power source to receive a hot voltage. The controllable electrical outlet may also comprise a load control circuit electrically coupled in series between the electrical connection and the electrical receptacle to control power delivered to the plug-in electrical load, and a control circuit coupled to the load control circuit and the communication circuit to control power delivered to the plug-in electrical load in response to an RF signal received via the RF communication circuit. The RF performance of the controllable electrical outlet may be substantially immune to devices plugged into the receptacles (e.g., plugs, power supplies, control devices, etc.) due to the operation of the resonant loop antenna. For example, degradation of the RF performance of the controllable electrical outlet may be less when the controllable electrical outlet includes the resonant loop antenna rather than other types of antennas, such as a monopole antenna. 
     In addition, the controllable electrical outlet may comprise a main printed circuit board on which the load control circuit is mounted. The resonant loop antenna may comprise an antenna printed circuit board comprising first and second layers and arranged perpendicular to the main printed circuit board. The first layer may have a main loop trace characterized by an inductance and a capacitance that are resonant at the specified frequency. The second layer may have a feed loop trace electrically coupled to the RF communication circuit and magnetically coupled to the main loop trace. 
     Further, an electrical contact of one of the receptacles may be coupled to an electrical contact of the other receptacle by an electrical contact coupling member. The main loop trace of the antenna printed circuit board may be mostly located above the coupling member in a direction extending from the main printed circuit boards towards a front surface of the electrical outlet. A top edge of a lower portion of the main loop trace of the antenna printed circuit board may be positioned above the coupling member in a direction extending from the main printed circuit boards towards a front surface of the electrical outlet. An inner portion of the main loop trace of the antenna printed circuit board may not overlap with the coupling member when viewed from the side. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a simple diagram of an example load control system having a controllable electrical outlet. 
         FIG.  2    is a simplified block diagram of an example controllable electrical outlet. 
         FIG.  3    is a perspective view of an example controllable electrical outlet. 
         FIG.  4    is a front view of another example controllable electrical outlet. 
         FIG.  5    is a front view of a portion of the controllable electrical outlet of  FIGS.  3  and  4   . 
         FIG.  6    is a left side view of the portion of the controllable electrical outlet shown in  FIG.  5   . 
         FIGS.  7  and  8    show first and second layers of an antenna printed circuit board. 
         FIG.  9    shows an example equivalent circuit of a resonant loop antenna. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a simple diagram of an example load control system  100  having a load control device (e.g., a controllable electrical outlet  110 ), a plurality of standard electrical outlets  120 , and a plurality of plug-in electrical loads (e.g., a computer  104  and a monitor  106 ). The controllable electrical outlet  110  may be adapted to be installed in a standard electrical wallbox (not shown). The controllable electrical outlet  110  may be adapted to be connected to a power source, such as an alternating-current (AC) power source  102  for receiving a hot voltage V H  (e.g., an AC mains line voltage, such as 120 V at 60 Hz or 230 V at 50 Hz) at a line voltage input  115  (e.g., a hot terminal). The controllable electrical outlet  110  may also be connected to the neutral side of the AC power source  102 . Alternatively or additionally, the controllable electrical outlet  110  may be configured to receive power from a direct-current (DC) power source. 
     The controllable electrical outlet  110  may comprise upper and lower receptacles  112 ,  114  into which the plug of a plug-in electrical load may be plugged. Each receptacle  112 ,  114  may have a hot connection and a neutral connection for receipt of the corresponding prongs of an electrical plug. The controllable electrical outlet  110  may provide the hot voltage V H  at the upper receptacle  112 , such that any electrical loads plugged into the upper receptacle are continuously powered. The controllable electrical outlet  110  may comprise an internal load control circuit (not shown), e.g., a relay for generating a switched-hot voltage V SH , which may be provided at the lower receptacle  114 . Accordingly, any electrical loads plugged into the lower receptacle  114  may be powered and unpowered in response to closing and opening the relay, respectively. Alternatively, the upper and lower receptacles  112 ,  114  could both provide the hot voltage V H  or both could provide the switched-hot voltage V SH , or the controllable electrical outlet  110  may provide the hot voltage V H  at the lower receptacle  114  and the switched-hot voltage V SH  at the upper receptacle  112 . 
     The controllable electrical outlet  110  may also comprise a controlled wired output  116  (e.g., a switched-hot terminal) for providing the switched voltage V SH  to the standard electrical outlets  120 . The standard electrical outlets  120  may each be configured to receive both the hot voltage V H  and the switched-hot voltage V SH . For example, the standard electrical outlets  120  may receive the hot voltage V H  via an electrical wire  126  connected to the line voltage input  115  of the controllable electrical outlet  110 . The standard electrical outlets  120  may receive the switched-hot voltage V SH  via an electrical wire  128  connected to the controlled wired output  116  of the controllable electrical outlet  110 . One or more of the standard electrical outlets  120  may also be connected to the neutral side of the AC power source  102 . The controllable electrical outlet  110  may “pass through” the hot voltage V H  to provide the hot voltage V H  from the AC power source  102  to the electrical wire  126  (e.g., directly). Alternatively, the electrical wire  126  may be wired to the hot side of the AC power source  102  around the controllable electrical outlet  110 , such that the hot voltage V H  does not pass through the controllable electrical outlet  110  on its way to the standard electrical outlet  120 . 
     Each of the standard electrical outlets  120  may comprise upper and lower receptacles  122 ,  124  into which an electrical load may be plugged. The upper receptacle  122  of a standard electrical outlet  120  may be electrically coupled to the electrical wire  126  for receiving the hot voltage V H , such that any electrical loads plugged into the upper receptacles are continuously powered. The lower receptacle  124  of a standard electrical outlet  120  may be electrically coupled to the electrical wire  128  for receiving the switched-hot voltage V SH , such that any electrical loads plugged into the lower receptacle may be powered and unpowered in response to the closing and opening, respectively, of the relay of the controllable electrical outlet  110 . Referring to the example of  FIG.  1   , the computer  104  may be adapted to be plugged into the upper receptacle  122  of one of the standard electrical outlets  120  (e.g., such that the computer  104  may be continuously powered), while the monitor  106  may be adapted to be plugged into the lower receptacle  124  of one of the standard electrical outlets (e.g., such that the monitor  106  may be turned on and off by the controllable electrical outlet  110 . Alternatively, the upper and lower receptacles  122 ,  124  of a standard electrical outlet  120  could both be coupled to the hot voltage V H  or could both be coupled to the switched-hot voltage V SH . 
     The controllable electrical outlet  110  may be configured to measure the magnitude of the total load current conducted by one or more of the plug-in electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120 . For example, the controllable electrical outlet  110  may be configured to measure the magnitude of a first load current conducted by the switched electrical loads (e.g., the electrical loads connected to the lower receptacle  124 ), and the magnitude of a second load current conducted by the unswitched electrical loads (e.g., the electrical loads connected to the upper receptacle  122 ). 
     The controllable electrical outlet  110  may be configured to control the relay to turn the electrical loads plugged into the lower receptacles  114 ,  124  and/or the standard electrical outlets  120  on and off in response to wireless signals, e.g., radio-frequency (RF) signals  108 , received from one or more input devices (e.g., RF transmitters). For example, the input devices may comprise a remote control device  130 , an occupancy sensor  140 , and/or a system controller  150  (e.g., a central controller or gateway device). As such, the controllable electrical outlet  110  may be controlled automatically (e.g., via an occupancy sensor  140 ) or manually (e.g., via a remote control device  130 ). Because the controllable electrical outlet  110  has the controlled wired output  116  for controlling the standard electrical outlets  120 , the standard electrical outlets do not need to be responsive to the RF signals  106  in order to switch the respective plug-in electrical loads on and off, thus greatly reducing the cost of the load control system  100 . 
     The remote control device  130  may comprise a battery-powered handheld remote control, or could alternatively be mounted to a wall or supported on a pedestal to be mounted on a tabletop. Examples of battery-powered remote control devices are described in greater detail in commonly-assigned U.S. Pat. No. 8,330,638, issued Dec. 11, 2012, entitled WIRELESS BATTERY-POWERED REMOTE CONTROL HAVING MULTIPLE MOUNTING MEANS, the entire disclosures of which are hereby incorporated by reference. 
     The remote control device  130  may transmit digital messages to the controllable electrical outlet  110  via the RF signals  108  in response to actuations of one or more buttons  132  for turning the electrical loads plugged into the lower receptacles  114 ,  124  on and off. The remote control device  130  may be associated with the controllable electrical outlet  110  by actuating one or more of the buttons  132  of the remote control device and an actuator (e.g., programming button  118 ) of the controllable electrical outlet  110 . The controllable electrical outlet  110  may also comprise a visual indicator  119 , e.g., a light-emitting diode (LED), which may be illuminated to provide feedback to a user during configuration and/or normal operation. Since the controllable electrical outlet  110  may be adapted to be installed in a standard electrical wallbox and the programming button  118  may be located on the controllable electrical outlet  110 , the programming button  118  may be easily accessed to associate the controllable electrical outlet  110  with the remote control device  130 . In addition, the controllable electrical outlet  110  may be installed in the same room in which the remote control device  130  is located to enhance the reliability of the RF communications. Examples of methods of associating wireless control devices are described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2008/0111491, published May 15, 2008, entitled RADIO-FREQUENCY LIGHTING CONTROL SYSTEM; U.S. Pat. No. 9,368,025, issued Jun. 14, 2016, entitled TWO-PART LOAD CONTROL SYSTEM MOUNTABLE TO A SINGLE ELECTRICAL WALLBOX; and U.S. Patent Application Publication No. 2014/0265568, published Sep. 18, 2014, entitled COMMISSIONING LOAD CONTROL SYSTEMS; the entire disclosures of which are hereby incorporated by reference. 
     The occupancy sensor  140  may be configured to detect occupancy and vacancy conditions in the space in which the load control system  100  is installed. The occupancy sensor  140  may transmit digital messages to the controllable electrical outlet  110  via the RF signals  108  in response to detecting the occupancy or vacancy conditions. The controllable electrical outlet  110  may be configured to turn the electrical loads plugged into the lower receptacles  114 ,  124  on in response to an occupancy condition and off in response to a vacancy condition. The occupancy sensor  140  may be associated with the controllable electrical outlet  110  by actuating a button on the occupancy sensor and/or an actuator (e.g., the programming button  118 ) of the controllable electrical outlet  110 . Since the controllable electrical outlet  110  may be located in the same room as the occupancy sensor  140 , the occupancy sensor  140  may be easily associated with the controllable electrical outlet  110  and reliable RF communications may be provided. Alternatively, the occupancy sensor  140  may operate as a vacancy sensor to only turn off the lighting loads in response to detecting a vacancy condition (e.g., to not turn on the lighting loads in response to detecting an occupancy condition). Examples of RF load control systems having occupancy and vacancy sensors are described in greater detail in commonly-assigned U.S. Pat. No. 8,009,042, issued Aug. 30, 2011 Sep. 3, 2008, entitled RADIO-FREQUENCY LIGHTING CONTROL SYSTEM WITH OCCUPANCY SENSING; U.S. Pat. No. 8,199,010, issued Jun. 12, 2012, entitled METHOD AND APPARATUS FOR CONFIGURING A WIRELESS SENSOR; and U.S. Pat. No. 8,228,184, issued Jul. 24, 2012, entitled BATTERY-POWERED OCCUPANCY SENSOR, the entire disclosures of which are hereby incorporated by reference. 
     The system controller  150  may be configured to communicate with a network  152  (e.g., a wireless or wired local area network) via a wired digital communication link  154  (e.g., an Ethernet communication link) for access to the Internet. Alternatively or additionally, the system controller  150  may be wirelessly connected to the network  152 , e.g., using LTE or Wi-Fi technology. For example, the system controller  150  may be configured to receive digital messages (e.g., Internet Protocol packets) via the network  152  from a network device (not shown), such as a smart phone (e.g., an iPhone® smart phone, an Android® smart phone, or a Blackberry® smart phone), a personal computer, a laptop, a wireless-capable media device (e.g., MP3 player, gaming device, or television), a tablet device, (e.g., an iPad® hand-held computing device), a Wi-Fi or wireless-communication-capable television, or any other suitable Internet-Protocol-enabled device. Examples of load control systems operable to communicate with network devices on a network are described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2013/0030589, published Jan. 31, 2013, entitled LOAD CONTROL DEVICE HAVING INTERNET CONNECTIVITY, the entire disclosure of which is hereby incorporated by reference. 
     The system controller  150  may operate as a central controller for the load control system  100 . The system controller  150  may operate as a gateway device to simply relay digital messages between the network  152  and the controllable electrical outlet  110 . The system controller  150  may be configured to transmit digital messages via the RF signals  108  to the controllable electrical outlet  110  for turning on and off the electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120 . Accordingly, the controllable electrical outlet  110  may be responsive to data received by the system controller  150  from the Internet, such as weather information and emergency status information. The system controller  150  may be further configured to transmit digital messages including one or more of: a timeclock command, a load shed command, a demand response command, a peak demand command, or time-of-day pricing information. The system controller  150  may be configured to control the controllable electrical outlet  110  in accordance with one or more timeclock events of a timeclock schedule, for example, to turn on the switched electrical loads during the day and to turn off the switched electrical loads at night. In addition, the controllable electrical outlet  110  may be configured to transmit feedback information, such as the status and energy consumption of the controlled loads (e.g., load current), back to the system controller  150 , which may be configured to report the information to an external device via the network  152 . 
     The controllable electrical outlet  110  may be configured to store information regarding the type of input device from which the controllable electrical outlet  100  received the digital message. The controllable electrical outlet  110  may be configured to store information regarding how the controllable electrical outlet  110  controlled the electrical loads in response to receiving the digital message. For example, this may be performed by the controller electrical outlet  110  after controlling the electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  in response to digital messages received via the RF signals  108 . The controllable electrical outlet  110  may transmit this information to the system controller  150 . The system controller  150  may analyze this information to determine how much energy is saved in response to certain types of input devices. For example, the system controller  150  may be configured to determine how much energy is saved as a result of the controllable electrical outlet  110  turning off the electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  in response to the occupancy sensor  140  versus how much energy is saved as a result of the controllable electrical outlet turning off the electrical loads in response to the remote control device  130 . 
     The controllable electrical outlet  110  may be configured to determine a balance between the amount of power consumed by the switched and unswitched electrical loads and report this information to the system controller  150 . The system controller  150  may be configured to transmit (e.g., to a network device via the network  152 ) a digital message including an alert that the amount of power consumed by the switched and unswitched electrical loads is unbalanced, for example, if the unswitched electrical loads are consuming a much greater amount of power than the switched electrical loads. For example, the alert may be included in an email or text message sent to a building manager. 
     Some plug-in electrical loads may still consume energy to maintain a standby mode when off. These electrical loads may be referred to as “vampire” loads. In addition, some plug-in power supplies may still consume energy even when the power supply is not charging a rechargeable load. The controllable electrical outlet  110  may be configured to detect whether one or more of the plug-in electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  are off, are in the standby mode, and/or are not charging a rechargeable load. The controllable electrical outlet  110  may be configured to determine that a plug-in electrical load is off, is in standby mode, and/or is not charging a rechargeable load if the magnitude of the load current conducted by the plug-in electrical load is less than a predetermined current threshold. For example, the controllable electrical outlet  110  may be configured to remove power from the plug-in electrical load if the controllable electrical outlet has received a digital message indicating a vacancy condition from the occupancy sensor  140  and has determined that the plug-in electrical load is off, is in the standby mode, and/or is not charging a rechargeable load. The controllable electrical outlet  110  will not remove power from the plug-in electrical load when the load is on or charging. For example, if a television is on, the television is considered to be in use independent of whether the room is occupied or not. Perhaps the user is listening to a particular program on the television from another room. When the television is turned off (e.g., changed to standby mode), the controllable electrical outlet  110  may disconnect the television from the AC power source when the room becomes unoccupied, for example, to save energy. 
     Some plug-in electrical loads may be critical loads that should be continuously powered (e.g., computers, medical devices, etc.). The controllable electrical outlet  110  may be configured to determine if a critical load is plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  and to prevent the critical load from being turned off, e.g., by disabling control of the critical load by the input devices (e.g., the remote control device  130 , the occupancy sensor  140 , and/or the controller  150 ). For example, the controllable electrical outlet  110  may be configured to determine that the computer  104  is plugged into one of the controllable electrical outlet  110  and/or the standard electrical outlets  120  by monitoring an electrical signature of the load current drawn by the computer. The controllable electrical outlet  110  may be configured to record and store the electrical signature of the load current conducted by the computer  104  when the computer  104  is plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120 , e.g., when the load control system  100  is first configured after installation. The controllable electrical outlet  110  may also have one or more predetermined electrical signatures of critical loads stored in memory prior to installation. During normal operation, the controllable electrical outlet  110  may be configured to compare an electrical signature drawn by an electrical load to one or more of the plurality of electrical signatures stored in memory. If the controllable electrical outlet  110  determines that an electrical load plugged into the controllable electrical outlet  110  and/or a standard electrical outlet  120  is a critical load via its electrical signature (e.g., that the electrical load is the computer  104 ), the controllable electrical outlet  110  may be configured to continuously power the electrical load at all times, e.g., by not disconnecting power from the electrical load in response to the remote control device  130 , the occupancy sensor  140 , and/or the controller  150 . 
     The controllable electrical outlet  110  may be configured to determine that the room in which an electrical load (e.g., the computer  104  and/or the monitor  106 ) is located is occupied in response to the magnitudes of the load currents conducted by the switched and/or unswitched electrical loads. For example, if the magnitude of the load current conducted by the computer  104  has increased and/or is actively changing, the controllable electrical outlet  110  may be configured to determine that the room in occupied. If the controllable electrical outlet  110  determines that one or more of the electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  are off, are in the standby mode, and/or are not charging a rechargeable load, the controllable electrical outlet  110  may determine that the room is vacant. The controllable electrical outlet  110  may be configured to turn on and off the electrical loads plugged into the controllable electrical outlet  110  and/or the standard electrical outlets  120  in response to the occupancy and/or vacancy conditions determined from the magnitudes of the load currents. 
     As described above, the remote control device  130 , the occupancy sensor  140 , and/or the system controller  150  may operate as a control-source device (e.g., an RF transmitter) and the controllable electrical outlet  110  may operate as a control-target device (e.g., an RF receiver). Alternatively or additionally, the control devices of the load control system  100  may comprise an RF transceiver, such that the devices are able to transmit and receive the RF signals  108 . For example, the controllable electrical outlet  110  may be configured to transmit feedback information, such as the status and energy consumption of the controlled loads, back to the system controller  150 , which may be configured to report the information to external devices via the network  152 . Examples of RF load control systems are described in commonly-assigned U.S. Pat. No. 5,905,442, issued on May 18, 1999, entitled METHOD AND APPARATUS FOR CONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTE LOCATIONS, and U.S. Pat. No. 9,553,451, issued Jan. 24, 2017, entitled LOAD CONTROL SYSTEM HAVING INDEPENDENTLY-CONTROLLED UNITS RESPONSIVE TO A BROADCAST CONTROLLER, the entire disclosures of which are both hereby incorporated by reference. 
     In addition, the controllable electrical outlet  110  may operate a signal repeater of the load control system  100 . For example, the controllable electrical outlet  110  may be configured to receive a digital message from one of the control devices of the load control system  100  (e.g., the remote control device  130 , the occupancy sensor  140 , the system controller  150 , or another controllable electrical outlet) and to retransmit the digital message to other control devices of the load control system (e.g., the system controller  150  or another controllable electrical outlet). Examples of RF load control systems having signal repeaters are described in greater detail in commonly-assigned U.S. Pat. No. 5,848,054, issued Dec. 8, 1998, entitled REPEATER FOR TRANSMISSION SYSTEM FOR CONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTE LOCATIONS, and U.S. Pat. No. 6,803,728, issued Oct. 12, 2004, entitled SYSTEM FOR CONTROL OF DEVICES, the entire disclosures of which are hereby incorporated by reference. 
     Since the controllable electrical outlet  110  may be adapted to be installed in the standard electrical wallbox and may be responsive to the RF signals  108  (e.g., that are transmitted directly to the controllable electrical outlet  110 ), the load control system  100  may not require any additional control devices (e.g., load control devices installed above the ceiling of the room, behind the walls of the room, or in an electrical closet) in order to provide control of the electrical loads plugged into the controllable electrical outlet  110  and the standard electrical outlets  120  in response to the RF signals  108 . This reduces the overall cost of the load control system  100  and simplifies the installation of the load control system  100  since no additional control devices need to be installed. 
     The controllable electrical outlet  110  could be responsive to other types of input devices, such as, for example, daylight sensors, radiometers, cloudy-day sensors, shadow sensors, window sensors, temperature sensors, humidity sensors, pressure sensors, smoke detectors, carbon monoxide detectors, air-quality sensors, motion sensors, security sensors, proximity sensors, fixture sensors, partition sensors, keypads, kinetic or solar-powered remote controls, key fobs, cell phones, smart phones, tablets, personal digital assistants, personal computers, laptops, timeclocks, audio-visual controls, safety devices (such as fire protection, water protection, and medical emergency devices), power monitoring devices (such as power meters, energy meters, utility submeters, utility rate meters), residential, commercial, or industrial controllers, interface devices with other control systems (such as security systems and emergency alert systems), and/or any combination of these input devices. One or more of the different types of input devices may be provided in a single load control system  100 . 
     The load control system  100  may also comprise one or more other types of plug-in electrical load and/or switched electrical loads, such as, for example, lighting loads (e.g., incandescent lamps, halogen lamps, electronic low-voltage lighting loads, and magnetic low-voltage lighting loads); dimming ballasts for driving gas-discharge lamps; light-emitting diode (LED) drivers for driving LED light sources; table or floor lamps; screw-in luminaires including dimmer circuits and incandescent or halogen lamps; screw-in luminaires including ballasts and compact fluorescent lamps; screw-in luminaires including LED drivers and LED light sources; motor loads, such as ceiling fans and exhaust fans; motorized window treatments; projection screens; motorized interior or exterior shutters; heating and/or cooling systems; heating, ventilation, and air-conditioning (HVAC) systems; air conditioners; compressors; electric baseboard heater controllers; controllable dampers; variable air volume controllers; fresh air intake controllers; ventilation controllers; hydraulic valves for use in radiators and radiant heating system; humidity control units; humidifiers; dehumidifiers; water heaters; boiler controllers; pool pumps; refrigerators; freezers; appliances; televisions; computer monitors; printers; copiers; fax machines; video cameras; audio systems; amplifiers; speakers; overhead projectors; visual presenters; smart boards; coffee makers; toasters; elevators; power supplies; generators; electric chargers; electric vehicle chargers; medical devices (e.g., heart/lung machines), or alternative energy controllers. 
       FIG.  2    is a simplified block diagram of an example controllable electrical outlet  200  that may be deployed as, for example, the controllable electrical outlet  110  of the load control system  100  shown in  FIG.  1   . The controllable electrical outlet  200  may be adapted to be mounted in a standard electrical wallbox. As shown, the controllable electrical outlet  200  may include a line-side hot electrical connection H LINE  (e.g., the line voltage input  115 ) and a line-side neutral electrical connection N LINE . The line-side hot electrical connection H LINE  and the line-side neutral electrical connection N LINE  may be coupled to an AC power source  202  (e.g., the AC power source  102 ) for receiving a power source voltage (e.g., the hot voltage V H ) from the AC power source  202 . The controllable electrical outlet  200  may further comprise a first load-side hot electrical connection H LOAD1  and a first load-side neutral electrical connection N OUT1 , which may be provided at an electrical receptacle (e.g., the upper unswitched receptacle  112  of the controllable electrical outlet  110 ) for powering a first electrical load (e.g., a first plug-in electrical load). The hot voltage V H  received at the line-side hot electrical connection H LINE  may be fed through the controllable electrical outlet  200  to the first load-side hot electrical connection H LOAD1 . 
     The controllable electrical outlet  200  may further comprise a second load-side hot electrical connection H LOAD2  and a second load-side neutral electrical connection N LOAD2 , which may also be provided at an electrical receptacle (e.g., the lower switched receptacle  114  of the controllable electrical outlet  110 ) for powering a second electrical load (e.g., a second plug-in electrical load). The controllable electrical outlet  200  may comprise a load control circuit  210  (e.g., a controllable switching circuit, such as a relay) coupled in series electrical connection between the line-side hot electrical connection H LINE  and the second load-side hot electrical connection H LOAD2 . The load control circuit  210  may comprise a relay having a single-pole single-throw (SPST) mechanical switch coupled in series electrical connection between the line-side hot electrical connection H LINE  and the second load-side hot electrical connection H LOAD2  and at least one operating coil for opening and closing the SPST switch. The load control circuit  210  may be rendered conductive and non-conductive in response to a control circuit  212  (e.g., a digital control circuit) to provide a switched-hot voltage (e.g., the switched-hot voltage V SH ) at the second load-side hot electrical connection H LOAD2  for turning the second electrical load on and off. For example, the control circuit  212  may be coupled to the at least one operating coil of the relay for opening and closing the SPST switch of the relay. The control circuit  212  may include one or more of a processor (e.g., a microprocessor), a microcontroller, a programmable logic device (PLD), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any suitable processing device. 
     The controllable electrical outlet  200  may further comprises a third load-side hot electrical connection H LOAD3  and a third load-side neutral electrical connection N LOAD3 . For example, the third load-side hot electrical connection H LOAD3  may be provided at a wired electrical connection, such as a screw terminal (e.g., the controlled wired output  116  of the controllable electrical outlet  110 ) for powering one or more downstream standard electrical outlets (e.g., the standard electrical outlets  120 ). The third load-side neutral electrical connection N LOAD3  may also be provided at a screw terminal. However, the third load-side neutral electrical connection N LOAD3  may be an optional connection since the third load-side neutral electrical connection N LOAD3  is coupled to the line-side neutral electrical connection N LINE  (e.g., which is coupled to the neutral side of the AC power source  202 ). The switched-hot voltage V SH  may be provided at the third load-side switched-hot electrical connection H LOAD3 . The downstream electrical outlets may receive the switched-hot voltage V SH  via an electrical wire  208  (e.g., the electrical wire  128  of  FIG.  1   ). The control circuit  212  may be configured to control the load control circuit  210  for connecting power to or disconnecting power from one or more of the receptacles of each of the downstream electrical outlets. The downstream electrical outlets may receive the hot voltage V H  via an electrical wire (e.g., the electrical wire  126  of  FIG.  1   ) that is wired to the line-side hot electrical connection H LINE  in the electrical wallbox of the controllable electrical outlet  200 . 
     Alternatively or additionally, the load control circuit  210  may comprise a dimmer circuit or driver circuit for controlling the amount of power delivered to the electrical loads connected to the second load-side hot electrical connection H LOAD2 , the third load-side hot electrical connection H LOAD3 , and/or the downstream electrical outlets. For example, the load control circuit  210  may comprise a bidirectional semiconductor switch (e.g., a triac), which may be controlled by the control circuit  212  using a standard phase-control dimming technique. 
     The controllable electrical outlet  200  may comprise one or more sense circuits for detecting and/or measuring the power being consumed by the electrical loads plugged into the controllable electrical outlet  200  and/or the downstream electrical outlets. For example, the controllable electrical outlet  200  may comprise a first sense circuit  214  coupled in series between the line-side hot electrical connection H LINE  and the first load-side hot electrical connection H LOAD1  for measuring a load current conducted by the first electrical load, and a second sense circuit  216  coupled in series with the load control circuit  210  for measuring a load current conducted by the second electrical loads and one or more electrical loads plugged into the downstream electrical outlets. The sense circuits  214 ,  216  may generate respective first and second sense signals V S1 , V S2  that are received by the control circuit  212  and are representative of the magnitudes of the respective load currents. 
     While the downstream electrical outlets may receive the hot voltage V H  via an electrical wire that is wired to the line-side hot electrical connection H LINE  as described above, the downstream electrical outlets could (e.g., alternatively) receive power through the controllable electrical outlet  200 . For example, the controllable electrical outlet  200  could comprise one or more additional electrical connections to which the unswitched receptacles of the downstream electrical outlets could be connected. The first sense circuit  214  could be coupled to the additional electrical connections, for example, such that a total load current of the first electrical load and the unswitched receptacles of the downstream electrical outlets may be conducted through the first sense circuit  214 . Accordingly, the magnitude of the first sense signal V S1  generated by the first sense circuit  214  may be representative of the total load current of the unswitched electrical loads coupled to the controllable electrical outlet  200 , and the magnitude of the second sense signal V S2  generated by the sense circuit  216  may be representative of the total load current of the switched electrical loads controlled by the controllable electrical outlet  200 . 
     The controllable electrical outlet  200  may comprise a communication circuit  218 , for example, a wireless communication circuit (e.g., an RF transceiver) coupled to an antenna  220  for transmitting and receiving digital messages (e.g., via wireless signals, such as the RF signals  108  of  FIG.  1   ) at a specified frequency (e.g., a transmission frequency, such as 434 MHz or 2.4 GHz). The communication circuit  218  may be configured to receive the digital messages via the RF signals  108  according to a predefined RF communication protocol, such as, for example, one or more of LUTRON CLEAR CONNECT, WIFI, BLUETOOTH, ZIGBEE, Z-WAVE, KNX-RF, LTE, or ENOCEAN RADIO protocols. Alternatively, the communication circuit  218  may comprise an RF transmitter for transmitting RF signals and/or an RF receiver for receiving RF signals. The antenna  220  may comprise a resonant loop antenna as will be described in greater detail below. 
     The controllable electrical outlet  200  may comprise a memory  222  communicatively coupled to the control circuit  212 . The control circuit  212  may be configured to use the memory  222  for the storage and/or retrieval of, for example, the serial numbers of the input devices (e.g., the wireless transmitters) to which the controllable electrical outlet  200  is responsive (e.g., to which the controllable electrical outlet is associated). The memory  222  may be implemented as an external integrated circuit (IC) or as an internal circuit of the control circuit  212 . 
     The controllable electrical outlet  200  may comprise one or more actuators  224  (e.g., buttons) for providing manual user inputs to the control circuit  212 . For example, the control circuit  212  may be configured to control the load control circuit  210  to render the relay conductive and non-conductive in response to actuations of the actuators  224 . In addition, the control circuit  212  may be configured to associate the controllable electrical outlet  200  with one or more of the input devices (e.g., the remote control device  130 , the occupancy sensor  140 , and the controller  150 ) in response to actuations of one or more of the actuators  224  (e.g., the programming button  118  of the controllable electrical outlet  110 ). The controllable electrical outlet  200  may also comprise a visual indicator circuit  226  that may comprise one or more LEDs for illuminating at least one visual indicator (e.g., the visual indicator  119 ) for providing feedback to a user during configuration and/or normal operation. 
     The controllable electrical outlet  200  may include a power supply  228  coupled between the line-side hot electrical connection H LINE  and the line-side neutral electrical connection N LINE  for generating a DC supply voltage V CC  for powering one or more of the control circuit  212 , the communication circuit  218 , the memory  222 , and other low-voltage circuitry of the controllable electrical outlet  200 . For example, the power supply  228  may comprise a non-isolated power supply (e.g., a Class 1 power supply) or an isolated power supply (e.g., a Class 2 power supply). 
     The control circuit  212  may be configured to control the load control circuit  210  to render the relay conductive and non-conductive in response to digital messages received via RF signals from input devices (e.g., the remote control device  130 , the occupancy sensor  140 , and the system controller  150  shown in  FIG.  1   ). For example, the control circuit  212  may receive digital messages including commands for providing manual control of the switched electrical loads (e.g., from the remote control device  130 ) and/or for providing automated control of the switched electrical loads (e.g., from the occupancy sensor  140  and/or the system controller  150 ). A system controller (e.g., the system controller  150 ) may be configured to transmit digital messages to the controllable electrical outlet  200  to control the switched electrical loads in accordance with one or more timeclock events of a timeclock schedule, for example, to turn on the switched electrical loads during the day and to turn off the switched electrical loads at night. In addition, the control circuit  212  may be configured to cause the communication circuit  218  to transmit, for example, one or more digital messages including information regarding the power consumed by the unswitched and/or switched electrical loads to the system controller. 
     After controlling the load control circuit  210  in response to digital messages received via the communication circuit  218 , the control circuit  212  may be configured to store in the memory  222  information regarding the type of input device from which the communication circuit  218  received the digital message, and/or how the control circuit  212  controlled the load control circuit  210  in response to that digital message. The control circuit  212  may transmit this information to the system controller for analysis regarding how much energy is saved in response to certain types of input devices. For example, the system controller  150  may be configured to determine how much energy is saved as a result of the controllable electrical outlet  200  turning off the controlled electrical loads in response to the occupancy sensor  140  versus how much energy is saved as a result of the controllable electrical outlet turning off the controlled electrical loads in response to the remote control device  130 . 
     The control circuit  210  may be configured to measure the amount of power consumed by the unswitched electrical loads (e.g., in response to the first sense signal V S1  generated by the first sense circuit  214 ) and/or to determine the amount of power consumed by the switched electrical loads (e.g., in response to the second sense signal V S2  generated by the sense circuit  216 ). The control circuit  210  may be configured to determine a balance between the amount of power consumed by the unswitched and switched electrical loads and report this information to the system controller. The controllable electrical outlet  200  and/or the system controller may be configured to transmit a digital message including an alert that the amount of power consumed by the unswitched and switched electrical loads is unbalanced (e.g., in an email or text message). 
       FIG.  3    is a perspective view and  FIG.  4    is a front view of an example controllable electrical outlet  300 , which may be an example of the controllable electrical outlet  110  of  FIG.  1    and/or the controllable electrical outlet  200  of  FIG.  2   . The controllable electrical outlet  300  may be mounted to a standard electrical wallbox. The controllable electrical outlet  300  may comprise a bezel portion  310  having a front surface  311  adapted to be received through an opening of a faceplate  312 . The controllable electrical outlet  300  may include circuitry that is similar to the circuitry of the controllable electrical outlet  200 . The circuitry may be housed in a rear enclosure portion  314  of the controllable electrical outlet  300 , for example, such that a wireless communication circuit (e.g., the wireless communication circuit  218 ) may be located inside of the wallbox. An actuator, such as a programming button  318  (e.g., one of the actuators  224 ) may be provided on the bezel portion  310 . The programming button  318  may be actuated to associate the controllable electrical outlet  300  with one or more input devices (e.g., wireless transmitters). The controllable electrical outlet  300  may also comprise a visual indicator  319  that may be illuminated to provide feedback to a user during configuration and/or normal operation. For example, the visual indicator  319  may be illuminated by a light source (e.g., an LED of the visual indicator circuit  226 ) located inside of the controllable electrical outlet  300 . 
     The front surface  311  of the bezel  310  may be located in a plane extending in a longitudinal direction L and a lateral direction A as shown in  FIG.  4   . The bezel portion  310  may comprise an upper receptacle  320  and a lower receptacle  322  for receiving the plugs of plug-in electrical loads. The upper receptacle  320  and the lower receptacle  322  may be spaced apart from each other in the longitudinal direction L. For example, the upper receptacle  320  may be an unswitched receptacle (e.g., similar to the upper receptacle  112  of the controllable electrical outlet  110  and/or the first load-side hot and neutral electrical connections H LOAD1 , N LOAD1  of the controllable electrical outlet  200 ) and the lower receptacle  322  may be a switched receptacle (e.g., similar to the lower receptacle  114  of the controllable electrical outlet  110  and/or the second load-side hot and neutral electrical connections H LOAD2 , N LOAD2  of the controllable electrical outlet  200 ). Each of the upper and lower receptacles  320 ,  330  may comprise a respective hot opening  322 ,  332  for receiving a hot blade of a plug, a respective neutral opening  324 ,  334  for receiving a neutral blade of the plug, and a respective ground opening  326 ,  336  for receiving a ground blade of the plug. 
     The rear enclosure portion  314  may comprise a hot screw terminal  318  for receiving a hot voltage from an AC power source (e.g., the line voltage input  115  of the controllable electrical outlet  110  and/or the line-side hot electrical connection H LINE  of the controllable electrical outlet  200 ). The rear enclosure portion  314  may also comprise at least one neutral terminal (not shown) adapted to be coupled to the neutral side of the AC power source (e.g., the line-side neutral electrical connection N LINE  of the controllable electrical outlet  200 ). The rear enclosure portion  314  may also comprise a wired-output screw terminal  319  adapted to be electrically connected to one or more downstream standard electrical outlets. The controllable electrical outlet  300  may provide a switched-hot voltage V SH  at the wired-output screw terminal  319 , such that the controllable electrical outlet  300  may be able to connect power to or disconnect power from one or more of the receptacles of one or more downstream electrical outlets. Examples of controllable receptacles are described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2015/0249337, published Sep. 3, 2015, entitled CONTROLLABLE ELECTRICAL OUTLET WITH A CONTROLLED WIRED OUTPUT, the entire disclosure of which is hereby incorporated by reference. 
     While the controllable electrical outlet  300  shown in  FIGS.  3  and  4    has U.S. style receptacles, the controllable electrical outlet  300  may alternatively or additionally have receptacles of styles used in other countries. In addition, the controllable electrical outlet  300  could comprise other types of receptacles, for example, one or more Universal Serial Bus (USB) connectors, and an internal power supply for charging an electrical device, such as the battery of a smart phone. 
       FIG.  5    is a front view and  FIG.  6    is a left side view of a portion of the controllable electrical outlet  300  showing a main PCB  340 , which may have mounted thereon the electrical circuitry of the controllable electrical outlet (e.g., as shown in  FIG.  2   ). The main PCB  340  may be located in a plane extending in the longitudinal direction L and the lateral direction A as shown in  FIG.  5    (e.g., parallel to the plane of the front surface  311  of the bezel portion  310 ). The controllable electrical outlet  300  may include a pair of upper hot contacts  350  and a pair of upper neutral contacts  352  configured to mechanically connect to (e.g., pinch) the hot and neutral blades of a plug, respectively, that are received through the upper hot and neutral openings  322 ,  324  in order to provide electrical connection to the hot and neutral blades. The controllable electrical outlet  300  may also include a pair of upper ground contacts  354  configured to mechanically connect to (e.g., pinch) the ground blade of the plug, which may be received through the upper ground opening  326 . The controllable electrical outlet  300  may include a pair of lower hot contacts  360  and a pair of lower neutral contacts  362  configured to mechanically connect to (e.g., pinch) the hot and neutral blades of a plug, respectively, that are received through the lower hot and neutral openings  332 ,  334  in order to provide electrical connection to the hot and neutral blades. The controllable electrical outlet  300  may also include a pair of lower ground contacts  364  configured to mechanically connect to (e.g., pinch) the ground blade of the plug, which may be received through the lower ground opening  336 . 
     The controllable electrical outlet  300  may include a load control circuit (not shown) for controlling the power delivered to the plug-in electrical loads plugged into the upper and lower receptacles  320 ,  330 . The load control circuit may be mounted to the main PCB  340 . For example, the upper and lower receptacles  320 ,  330  may be controlled in unison because the upper contacts  350 ,  352  are coupled to the lower contacts  360 ,  362  by respective electrical contact coupling members, e.g., hot and neutral coupling members  370 ,  372  that extend in the longitudinal direction L between the contacts. The hot and neutral coupling members  370 ,  372  may be cut (e.g., made non-conductive at a point along the length) to provide for separate control of the upper and lower receptacles  320 ,  330 . The upper ground contacts  354  may be coupled to the lower ground contacts  364  by a ground coupling member  374 , which may be coupled to mounting tabs  376  of the controllable electrical outlet  300 . The ground coupling member  374  may extend in the longitudinal direction L between the mounting tabs  376 . 
     If the load control circuit of the controllable electrical outlet  300  is configured to adjust the amount of power delivered to the plug-in electrical loads (e.g., the load control circuit is a dimmer circuit), the respective electrical outlet may comprise a protrusion at the controlled receptacle for preventing a standard electrical plug from being plugged into the controlled receptacle. Examples of such protrusions for preventing standard plugs from being plugged into a controlled receptacle are described in greater detail in commonly-assigned U.S. Pat. No. 7,198,523, issued Apr. 3, 2007, and U.S. Pat. No. 7,311,558, issued Dec. 25, 2007, both entitled RECEPTACLE AND PLUG THEREFOR, the entire disclosures of which are hereby incorporated by reference. 
     The controllable electrical outlet  300  may also comprise a resonant loop antenna  400  having an antenna PCB  402 .  FIGS.  7  and  8    show first and second layers  410 ,  412 , respectively, of the antenna PCB  402 , where the first and second layers may be overlaid over each other. The antenna PCB  402  may be made of a non-conductive substrate, and may be substantially rectangular or square in shape. The antenna PCB  402  may comprise first and second tabs  404 ,  406  at a bottom edge  408  of the antenna PCB. The first and second tabs  404 ,  406  may be received in openings in the main PCB  340 , such that the antenna PCB  402  may be mechanically connected to the main PCB and oriented perpendicular to a plane of the main PCB. 
     The resonant loop antenna  400  may comprise a main loop trace  412  (e.g., a main loop) disposed on (e.g., laid out on) the first layer  410 , which may be an outer layer of the antenna PCB  402 . The main loop trace  412  may be located near a top side  405  of the antenna PCB  402 . The main loop trace  412  may have a break  414  with a capacitor  416  provided across the break. The capacitor  416  may be a variable capacitor to allow for tuning of a resonant frequency of the main loop trace  412 . The first layer  410  may also have first and second electrical pads  418 ,  419  on the first tab  404  to allow for electrical connection to communication circuit  218  (e.g., the RF transceiver) on the main PCB  340  (e.g., soldered to electrical pads on the main PCB). The second tab  406  may provide mechanical support for the antenna PCB  402 . 
     The resonant loop antenna  400  may also comprise a feed loop trace  422  (e.g., a feed loop) disposed on (e.g., laid out on) the second layer  420 , which may be another outer layer or an internal layer of the antenna PCB  402 . The feed loop trace  422  may be coupled to electrical pads  418 ,  419  on the first layer  410  through vias  424 . The first electrical pad  418  may be electrically coupled to the RF transceiver on the main PCB (e.g., the RF feed) and the second electrical pad  419  may be electrically coupled to an antenna ground. The main loop trace  412  on the first layer  410  may overlap the feed loop trace  422  on the second layer  420 . The feed loop trace  422  does not extend to the top edge  405  of the antenna PCB  402  as shown in  FIG.  8   . The main loop trace  412  may be magnetically coupled to the feed loop trace  422  and may be electrically isolated from the feed loop trace. When a signal is transmitted from the RF transceiver to the first electrical pad  418 , current may flow through the feed loop trace  422  on the second layer  420 . This may cause current to be induced in the main loop trace  412  on the first layer  410  due to the magnetic coupling of the main loop trace  412  and the feed loop trace  422  resulting in an RF signal being transmitted from the controllable electrical outlet. 
       FIG.  9    shows an example equivalent circuit of the resonant loop antenna  400 . The main loop (e.g., the main loop trace  420 ) may be the primary radiating element of the antenna  400  and may include an inductance L and capacitance C in series (e.g., where the capacitance C may be a variable capacitance). When energized, the main loop may resonate at a frequency determined by the values of the inductance L and the capacitor C and enables the transmitting and receiving of RF signals via a radiation resistance R r , which may be a representation of the energy delivered to radiation. The losses in the main loop may be represented by a loss resistance R l . The main loop may be primarily magnetically coupled to the feed loop (e.g., the feed loop trace  422 ). This coupling is shown schematically in  FIG.  9    by an ideal transformer T. The feed loop may include a magnetizing inductance L m , a leakage inductance L l , and two ends  430  that connect to the RF transceiver. The feed loop may allow for the conduction of signals between the RF transceiver and the main loop. 
     In this way, the antenna  400  may be adapted to receive RF signals via the main loop, with those radio frequency signals being electromagnetically coupled to the feed loop for input to the RF transceiver. Conversely, the feed loop may receive a feed signal to be transmitted from the RF transceiver, and may electromagnetically couples the feed signal to the main loop for transmission of RF signals to an external wireless device (e.g., the system controller  150 ). Examples of load control devices having resonant loop antennas are described in greater detail in commonly-assigned U.S. Pat. No. 7,362,285, issued Apr. 22, 2008, entitled COMPACT RADIO FREQUENCY TRANSMITTING AND RECEIVING ANTENNA AND CONTROL DEVICE EMPLOYING SAME, and U.S. Pat. No. 7,592,967, issued Sep. 22, 2009, entitled COMPACT ANTENNA FOR A LOAD CONTROL DEVICE, the entire disclosures of which are hereby incorporated by reference. 
     Referring back to  FIGS.  5  and  6   , the antenna PCB  400  may be oriented perpendicular to the plane of the main PCB  340  and may extend from the main PCB  340  towards the front surface  311  in a transverse direction T. The antenna PCB  400  may be arranged substantially parallel to the ground coupling member  374 , e.g., in a plane extending in the longitudinal direction L and the transverse direction T as shown in  FIG.  6   . As shown in  FIG.  5   , the antenna PCB  400  may be centrally located in the controllable electrical outlet  300  and may be located away (e.g., as far away as possible) from the contacts  350 - 364  and the coupling members  370 - 374 . The antenna PCB  400  may be located away from the upper contacts  350 ,  352  and the lower contacts  360 ,  362  in the longitudinal direction L (e.g., approximately centrally located between the upper contacts and the lower contacts). As shown in  FIG.  5   , the antenna PCB  400  may be located away from the neutral coupling member  372  and the ground coupling member  374  in the lateral direction A (e.g., approximately centrally located between the neutral coupling member  372  and the ground coupling member  374 ). Alternatively, the antenna PCB  400  may be located between (e.g., approximately centrally located between) the hot coupling members  370  and the ground coupling member  374 . In addition, the antenna PCB  400  may also be arranged in a plane extending in the lateral direction A and the transverse direction T, for example, if the ground coupling member  374  does not extend adjacent to the center of the main PCB  340 , but extends near the edges of the main PCB. While not shown in  FIGS.  5  and  6   , the contacts  350 - 364  and the coupling members  370 - 374  may be supported by a cradle (e.g., a plastic, non-conductive support cradle), which may be positioned between the main PCB  340  and the contacts and coupling members. The cradle (not shown) may include an opening through which the antenna PCB  400  may extend. 
     As shown in  FIG.  6   , the main loop trace  412  may be mostly located above the hot and neutral coupling members  370 ,  372  in a direction extending from the main PCB  340  towards the front surface  311  of the controllable electrical outlet  300  (e.g., along the transverse direction T, i.e., to the right in  FIG.  6   ), which may improve the RF performance of the controllable electrical outlet  300 . A top edge  442  of a lower portion  440  of the main loop trace  412  may be positioned above the hot and neutral coupling members  370 ,  372  in the transverse direction T, such that an inner portion  444  of the main loop trace  412  may not overlap with the coupling members  370 ,  372  in the transverse direction T (e.g., when viewed from the side as shown in  FIG.  6   ). 
     The RF performance of the controllable electrical outlet  300  may be substantially immune to devices plugged into the receptacles  320 ,  322  (e.g., plugs, power supplies, control devices, etc.) due to the magnetic coupling between the main loop trace  412  and the feed loop trace  422  and the orientation of the main loop trace (e.g., perpendicular to the plane of the main PCB  340 ). For example, degradation of the RF performance of the controllable electrical outlet  300  may be less when the controllable electrical outlet includes the resonant loop antenna  400  rather than other types of antennas, such as a monopole antenna. 
     Since the main loop trace  412  may be electrically isolated from the feed loop trace  422  and the AC power source to which the controllable electrical outlet  300  is coupled (e.g., the AC power source  102 ,  202 ), the top edge  405  of the antenna PCB  402  may be located close to the front surface  311  and the receptacles  320 ,  322  of the controllable electrical outlet. In addition, because the main loop trace  412  may be isolated from the feed loop trace  422 , the controllable electrical outlet  300  does not need to include an isolated power supply for powering the communication circuit  218 , but can include a non-isolated power supply, which may be lower cost and smaller than an isolated power supply.