MXPA00005499A - Automatic gain-controlled vhf/uhf antenna tuning apparatus - Google Patents

Abstract

An antenna tuning apparatus for VHF/UHF antenna comprises an automatic gain control (AGC) arrangement, including an amplifier, the gain of which is controlled by the AGC arrangement, and a plurality of impedance matching networks which are coupled between an antenna input of the tuning apparatus and the AGC-controlled amplifier. A remote controller is provided to select both channels of a television apparatus, for which the tuning apparatus provides VHF/UHF signals, and proper matching networks suitable for respective ones of selected channels simultaneously. Each one of the plurality of matching networks exlusively provides the AGC arrangement with a respective group of RF signals which includes a plurality of receivable broadcast channels. The gain of the amplifier is controlled in response to the level of the group of RF signals.

Description

ANTENNA TUNING APPARATUS OF VHF / UHF ANTENNA CONTROLLED GAUGE AUTO MÁTICA FIELD OF THE I NVEN C ION The present invention relates generally to a tuning apparatus for antennas that receive transmission unit signals such as television signals. BACKGROUND OF THE I NVENTION Conventional television antenna systems generally include two separate antennas for respective reception of VH F and UH F. The antenna to receive the VH F bands employs a pair of telescopic elements that form a dipole with each of the elements that have a maximum length of 1.5 to 2.5 m. The two elements are commonly assembled to allow the elements to separate to increase or decrease the length of the dipole and these elements are commonly referred to as "rabbit ears". The U H F antenna for interiors is commonly a loop having a diameter of approximately 20 cm. A problem associated with conventional indoor antenna systems is that the physical dimension of the VHF dipole is inconveniently long for the common arrangement in a room and that the length as well as the direction of the dipole elements may have to be adjusted depending on of the channels that are received. The second problem is that the operation of such conventional antennas for indoor VH F / U H F changes in response to changes in physical conditions around the antenna elements. For example, it is difficult for a user to make the proper adjustment for the antennas since a human body that makes contact with an antenna changes the electromagnetic conditions associated with the elements of the antenna. The third problem is that conventional indoor antenna systems do not always provide a sufficient level of signal for good reception. There is a need for an antenna system that includes compact size antennas that are capable of receiving a sufficient level of signals across all the VH F / U H F transmission bands of frequencies without any physical adjustment. Additionally, an antenna system is needed that can be used for indoor or outdoor applications. BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, a tuning apparatus for VHF / UHF signals comprises an automatic gain control (AGC) configuration including an amplifier for controlling the gain of the amplifier and a plurality of amplifier networks. impedance coupling coupled between an input and the amplifier. Each of the plurality of coupling networks provides exclusively the configuration of the automatic gain control with a respective group of radio frequency signals which includes a plurality of transmittable channels that can be received. The gain of the amplifier is controlled in response to the level of the signal and signal frequency.

Another aspect of the invention is the following: In an antenna system for providing VHF / UHF signals for a receiver, the receiver having a remote control transmitter for generating control signals for selecting individual VHF / UHF signals corresponding to channels of respective transmission, the apparatus comprises (1) a plurality of coupling networks coupled between an input to which an antenna may be coupled and an output circuit for providing impedance coupling between the antenna and the output circuit wherein each of the plurality of coupling networks exclusively provides the output circuit with a respective group of radio frequency signals that includes a plurality of transmission channels that can be received and (2) control means coupled to the plurality of coupling network and that respond to the control signals generated by the remote control transmitter to select the signals indi of the VHF / UHF signals corresponding to the respective channels to select one of the networks of the plurality of coupling networks. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1 illustrates one embodiment of the aspects of the disclosed planar antenna system including a planar antenna and a tuner unit including a tuning configuration and a gain controllable amplifier; Figure 2 illustrates an exemplary application for the use of the planar antenna system; Figure 3 illustrates another exemplary application for the use of the planar antenna system; Figure 4 illustrates a top view of a modality of the planar antenna; Figure 5 illustrates a bottom view of the modality of the planar antenna shown in Figure 4; Figure 6 illustrates characteristics of standing wave amplitude ratio (50-800 MHz) of the planar antenna mode; Figure 7 illustrates a radiation pattern of the planar antenna mode at one of the low band VHF television channel frequencies (67.25 MHz); and Figures 8-10 are schematic diagrams of a modality of aspects of the described tuner unit including a plurality of selectable coupling networks and a gain controllable amplifier controlled by an included automatic gain control configuration. In the different figures, the same or similar elements shown are identified by the same reference numbers. DESCRIPTION OF THE PREFERRED MODALITY In this application, the term "television set" is used to describe any television set that includes at least one television tuner (such as television receivers, jg tape recorders, etc.). .

Figure 1 illustrates a planar VHF / UHF antenna system that includes aspects of the present invention. The planar antenna system includes a planar antenna 10 and a tuning unit 30. The planar antenna 10 and the tuning unit 30 are coupled by a coaxial cable 20. With respect to this exemplary embodiment, the characteristic impedance of the coaxial cable 20 is 75 Ü. The tuning unit 30 includes the tuning configuration 31 and the gain controllable amplifier 33. The gain controllable amplifier 33 is optional and may not be included in the tuning unit 30 when the television transmission signals are strong enough. The tuning configuration 31 includes a plurality of impedance matching networks 610 (e.g., bandpass filters) for the respective plurality of transmission frequency bands (see details in Figure 8). The common infrared (IR) remote controller 40 is used to select the coupling networks in the tuning unit 30 and the channels for the television set 50 simultaneously. Of course, a separate infrared remote controller can be used to select a suitable coupling network automatically using an included automatic gain control configuration (see the schemes in Figures 8-10). Figure 2 illustrates one of the applications for indoor use of the planar antenna system. Here the planar antenna 10 is located inside the planar antenna box 11 which is made of dielectric materials. The box of the antenna 11, including the planar antenna 10, hangs on the wall while the tuning unit 30 is placed on top of the television set 50. The coaxial cable 20 is used to couple between the planar antenna 10 and the tuning unit 30. The antenna box 11 may be designed to be waterproof for outdoor use. Figure 3 illustrates another application for the use of the planar antenna system. Here the tuning unit 30 is placed below the antenna box 11 which is placed on the top of the television set 50. Figures 4 and 5 illustrate respective upper and lower views 100, 200 of the planar antenna 10. Antenna elements of the planar 10 antenna are different from those of loop or dipole antennas (rabbit ears) traditional in many aspects. In particular, the elements are developed based on microband techniques and the unique patterns of the elements allow the planar antenna system to provide omnidirectional reception of the television signals as can be observed in the characteristic radiation pattern of the antenna that It is shown in Figure 7. Therefore, it is not necessary to adjust the direction of the antenna once it is installed. It is considered that this omnidirectional feature on the horizontal platform results from the fact that most of the radio frequency current flows along the edges of each of the elements of the planar antenna. With reference to the exemplary embodiment shown in Figures 4 and 5, the antenna elements are directly engraved on a printed circuit board (PCB) such as the "MC3D" Medium Frequency Laminate model, manufactured by Glasteel Industrial Laminates (board). printed circuit of double side of 0.15 cm of thickness, with dielectric constant of 3.53 +/- 0.08). The size of the printed circuit board is approximately 30 x 30 cm. Both antenna elements, VHF and UHF are formed on each side of the printed circuit board, and the VHF and UHF elements on one side are substantially identical in shape, to the respective VHF and UHF elements on the other side of the board. printed circuit. In addition, the former are rotated 90 degrees with respect to the latter. The VHF antenna elements have a unique "H" shape configuration. The antenna element at each end of the "H" shape is approximately 6.5 cm wide x 30 cm long. Both ends of the "H" shape are connected together with approximately 2.5 cm wide by 17.5 cm long micro-band transmission line to complete the "H" shape. As described above, the two "H" shaped VHF elements on the respective sides of the printed circuit board are substantially identical in shape, and the VHF element on the upper side rotates 90 degrees from that on the underside of the circuit board printed.

Each of the elements of the "H" form for VH F signals is formed as a combination of the following three separate regions (the reference numbers for the corresponding corresponding regions on the lower side are shown in the parentheses): © main region in the form of "S" 120 (220); ® first complementary region 150 (250); and F second complementary region 160 (260). The first complementary region 150 (250) is approximately 6.5 cm wide by 13.7 cm in length and is separated from the main region 120 (220) by a space of approximately 2.5 mm. The first complementary region 150 (250) is electrically coupled to the main region 120 (220) through the inductor 151 (251), for example the high-Q surface mounted integrated inductor of 100 μH. It has been found that this configuration extends the effective electrical length of the main region 120 (220). The second complementary region 160 (260) is substantially identical to the first complementary region 150 (250) in dimensions. The second complementary region 160 (260) is coupled to the first main region 120 (220) through the capacitor 161 (261), for example, the largest integrated circuit capacitor on the surface of 15 pF. It has been found that the second complementary region 160 (260) coupled via capacitors 161 (251) Significantly improves the total refractory stationary voltage amplitude (VSWR) characteristics of the planar before R-a for the VHF television frequency band (50-88 MHz). There is a reflecting region 140 only on the upper side of the printed circuit board. The reflecting region 140 functions as a reflector for the first complementary region 150. It has been found that the reflecting region 140 improves the overall performance of the planar antenna in the higher UHF television frequency band (174-216 MHz). The UHF antenna elements 170, 270 also have an "H" shaped configuration and are formed on the respective sides of the printed circuit board. As described above, these two UHF elements are also substantially identical in shape, and one rotates 90 degrees of the other. Each end of the "H" shaped element has a square shape and is approximately 6.5 cm wide by 6.5 cm long. The two ends are connected together with approximately 2.5 cm in width by 3.8 cm in length of micro band transmission line to form the "H" shaped configuration. The UHF element 170 (270) is coupled to approximately the midpoint of the micro-band transmission line of the VHF element 120 (220) through the inductor 171 (271), for example, the integrated circuit inductor surface of Q high of 100 μH. The upper side of the printed circuit board also includes a land-to-ground region 130. The land-to-land region 130 has a square shape and is approximately 6.5 x 6.5 cm). The female connector "F" 131 is located in the region of plane to ground 130. The feet (line to ground) of the connector 131 are connected to the region of plane to ground 130 and, when drilling through the printed circuit board , another region from ground to ground 230 on the underside of the printed circuit board. The dimension of the plane-to-ground region 130 is approximately 6.5 cm in width by 16.5 cm in length. The signal line of the connector 131 is connected to the signal transmission line 132 formed on the upper side of the printed circuit board. It has been found that both plane-to-ground regions 130, 230 contribute to the stabilization of the total operation of the planar antenna system independently of the changes in physical conditions around the planar antenna. As shown in Figure 4, a balanced transformer - unbalanced 4: 1 133 is placed on the upper side of the printed circuit board for impedance coupling between the elements of the planar antenna and the coaxial cable 20. The ends of the first winding of the transformer 133 are coupled to the respective ends of the connection point 136 and the connection region 134. The connection point 136 is placed approximately in the middle of the transmission line of the VH F 120 elements. The connection region 134 is connected to the connection point 234 of the VH element F 220 on the lower side via two holes through. The ends of the second winding are coupled to the transmission line 132 and the ground plane 130. The coupling capacitor 135 (4 pF) is coupled between the center of the second winding and the ground plane 130 for better impedance coupling. Alternatively, a variable capacitor (2-6 pF) can be coupled between the two ends of the second winding as shown in Figure 8. Other characteristics of the planar antenna are that unlike conventional microband antennas, there is no flat to flat ground on the underside of the printed circuit board, which completely covers the region below the antenna elements formed on the upper side of the printed circuit board. With respect to conventional microband antennas, the bandwidth of these antennas is proportional to the distance between the antenna elements on one surface and the region of plane to flat ground on the other side of the substrate used (i.e. thickness of the substrate). It has been found that the elimination of this type of region from flat to flat ground contributes to the broadband characteristic of the planar antenna. As a reference, see Munson, Robert E., "Micro Band Antennas" in the Antena Engineering Handbook (3rd edition) (McGraw Hill, 1993). Figure 8 shows the schematic diagram of a portion of the tuning unit 30 that includes a plurality of coupling networks. As for this particular exemplary embodiment, five bandpass filters 610 (BPF) are used as coupling networks, and are pre-tuned to five different respective bands of transmission frequencies. These are the following: VH F 1: 54 - 72 MHz (Channels 2 to 4 in the United States of North America) VH F 2: 76 - 88 MHz (Channels 5 to 6 in the United States of North America) VH F 3: 174 - 192 MHz (Channels 7 to 9 in the United States of North America) VH F 4: 192 - 216 MHz (Channels 10 to 13 in the United States of North America) UH F: 470 - 800 MHz (UHF channels in the United States of America) As shown in Figures 8-10, the band selection will be made in accordance with the reception channels. A user selects a suitable band using a remote I R controller. However, this selection can be made automatically in response to the level of the automatic gain control signal (AGC) for the gain controllable amplifier 33a. The automatic gain control signal operates to reduce the gain of the amplifier 33a when a suitable coupling network is selected for a reception channel. By means of the automatic gain control configuration, the output signal level of the tuning unit 30 is maintained at a desirable predetermined level, independently of the variation of the strength of the television signals received through a whole band of frequencies. In the exemplary embodiment shown in Figures 8 and 9, the automatic gain control configuration includes the gain controllable amplifier 33a; the stage of the signal amplifier 720; the signal divider 710; the 730 CD rectifier; and CD offset voltage compensation circuits 750. It has been found that a combination of a plurality of selectable front end bandpass filters 610and the subsequent automatic gain control setting makes the automatic gain control operate properly across the entire bands of VHF / UHF television frequencies (50-800 MHz). For a faster adjustment of the amplifier 33a, a microprocessor can be used to control the gain of the amplifier 33a together with a memory storing lower at the desirable levels of automatic gain control for respective transmission channels. In addition, the tuning unit 30 may additionally include a radio frequency signal selection switch that allows a user to select between the radio frequency signals of the planar antenna and those of other signal sources (eg, a satellite dish). , cable, video tape recorder, etc.). In Figure 10, the configuration of the infrared remote sensor 800 includes the infrared signal receiver 830, the microprocessor 810, the multiplexer 850, five light emitting diodes (LED) and two manually controlled switches R, L. The LED1, LED2 , LED3, LED4 and LED5 indicate the selections of the respective bands of five different bands of transmission frequencies, namely VHF-1, VHF-2, VHF-3, VHF-4 and UHF in Figure 8. That is, the Five LEDs indicate selections from one of the five different BPF 610. For example, LED1 lights when the BPF is selected for VHF-1. Manual switches R, L function as "up-down" switches for band selection so that a user without a remote controller can still select suitable bands of frequencies. The IR receiver 830 coupled to the microprocessor 810 receives IR signals from the remote controller. Then, the microprocessor 810 generates control signals. In response to the control signals, the multiplexer 850 coupled to the microprocessor 810 sends band selection signals A. B. C. D. E to respective PIN diodes D1, D2, D3, D4 and D5. Here, the multiplexer 850 functions as a plurality of digitally controlled analog switches. The power supply configuration 840 includes two voltage regulators 870, 890. Although the invention has been described with reference to a preferred embodiment, it is understood that the words that have been used herein are a description, rather than limitation. Those skilled in the art may consider numerous alterations or modifications of the antenna system of the present invention without departing from the spirit and scope of the invention and the principles and aspects thereof. For example, the planar antenna system can be used not only to receive analog and / or digital television signals but also to receive analog and / or digital audio or data signals.

Claims (2)

1. CLAIMS l.A tuning apparatus for VHF / UHF signals, comprising: a source of VHF / UHF input signals; an amplifier for amplifying such input signals; an automatic gain control (AGC) configuration including said amplifier to control the gain of said amplifier; a plurality of coupling networks coupled between such a source of VHF / UHF input signals and said amplifier to provide impedance coupling between said input signal source and such an amplifier; each of said plurality of coupling networks exclusively provides such automatic gain control configuration with a respective group of radio frequency signals that includes a plurality of transmittable channels that can be received, wherein: the gain of said amplifier is controlled in response to the level of such a group of radio frequency signals.
2. 2. In an antenna system to provide signals of VHF / UHF for a receiver, such receiver has a remote control transmitter for generating control signals for selecting individual signals of said VHF / UHF signals corresponding to respective transmission channels, the apparatus comprises: a plurality of coupled coupling networks between an input to which an antenna may be coupled and an output circuit for providing impedance coupling between said antenna and said output circuit; each of said plurality of coupling networks exclusively provides said output circuit with a respective group of radio frequency signals that includes a plurality of transmission channels that can be received; and control means coupled to such a plurality of coupling networks and responsive to such control signals generated by said remote control transmitter to select such individual signals from said VHF / UHF signals corresponding to the respective channels to select ones from the mentioned plurality of coupling networks. (54) Title: AUTOMATIC CONTROLLED VHF / UHF ANTENNA TUNING APPARATUS (57) Summary: An antenna tuning device for VHF / UHF antenna comprises an automatic gain control (AGC) configuration whose gain is controlled by the automatic gain control configuration, and a plurality of impedance matching networks that are coupled between an antenna input of the tuning apparatus and the amplifier controlled by the automatic gain control. A remote controller is provided for selecting both channels of a television set, for which the television set provides VHF / UHF signals, and suitable mating networks for the simultaneously selected channels. Each of the plurality of coupling networks exclusively provides the automatic gain control configuration with a respective group of radio frequency signals that includes a plurality of transmittable channels that can be received. The gain of the amplifier is controlled in response to the group level of the radio frequency signals.