WO2000041268A1

WO2000041268A1 - Box-kite uhf/vhf television and radio communications antenna

Info

Publication number: WO2000041268A1
Application number: PCT/US2000/000150
Authority: WO
Inventors: Dan L. Volger
Original assignee: TEVCA TECHNOLOGIES Inc
Current assignee: TEVCA TECHNOLOGIES Inc
Priority date: 1999-01-05
Filing date: 2000-01-05
Publication date: 2000-07-13
Anticipated expiration: 2001-07-05
Also published as: AU2599600A

Abstract

A 'box-kite', loop antenna system (100) with a detector loop (120) fed at the corner and provided on a substrate. The loop antenna may be employed with a parabolic reflector (130), a Faraday shield and fed with a transmission line, impedance matching transformer for an umbalanced line.

Description

BOX-KITE UHF/VHF TELEVISION AND RADIO COMMUNICATIONS ANTENNA

BOX-KITE UHF/VHF TELEVISION

AND RADIO COMMUNICATIONS ANTENNA BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to toy power tools, and more particularly toy power tools that can transform from one configuration to another and that produce cutting sounds and motor sounds during use . Description of the Related Art A system of wires or other conductors used to transmit or receive radio or other electromagnetic waves (see RADIO; TELEVISION) . In a transmitting antenna, the signal from an ELECTRIC CIRCUIT causes electrons in the antenna to oscillate; these moving electric charges generate ELECTROMAGNETIC RADIATION, which is then transmitted through space.

The distribution pattern of the transmitted wave depends on the design of the antenna,- radio broadcast- station antennas are frequently designed to emit waves in all directions, whereas those used for RADAR and for certain communication systems focus the waves in a single direction. In a receiving antenna, electromagnetic waves cause the electrons in the antenna to oscillate, inducing a signal that can be detected by an electric circuit. In general, a longer antenna is used to transmit or receive signals of longer wavelengths.

Theoretically, the same antenna can be used both for sending and for receiving signals, but in practice, transmitting antennas are constructed to handle higher power loads than receiving antennas. Phased array antennas, used for long-range radar and radio astronomy, are composed of large groupings of individual antennas that are aimed electronically by changing the relative phase of the signal at each antenna.

The antenna systems delivered with most televisions "out of the box" today, such as the conventional "LOOP" or "Rabbit Ears" give poor performance and are inadequate to serve the need of quality reception of local channels, to be mixed with cable and satellite content from new "third generation" cable, satellite and TV receivers that add an additional "local" antenna input for the purpose of also then receiving the terrestrial broadcast in the UHF and VHF bands, plus cable and satellite modes.

Both aesthetically pleasing in appearance and superior performance to conventional antennas, the "Box-Kite" antenna presented herein has the highest gain density for it's size of any antenna made, giving performance similar to a larger Yagi Array.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances and has as an object an improve directional antenna array.

A further object of the present invention is 6. A directional antenna adapted to receive broadcast signals, the directional antenna including a substantially rectangular primary antenna loop adapted to receive a horizontal and vertical polarization of one of a transmission wavefront and/ or a waveshape. The primary antenna loop is adapted to minimize dipole wavelength matching at a midband frequency and a non-conductive substrate or insulator is employed, wherein the primary antenna is coupled to the non-conductive substrate and wherein the substrate produces a minimal effect at an operating frequency of said directional antenna. An antenna detector array, the antenna detector array coupled to said directional antenna through the substrate or insulator and positioned in front of a reflective surface at a rear of a parabolic curve, at or near a focal point of the parabolic curve. There is at least one secondary antenna loop of a different length from that of the primary antenna loop, whereby the secondary antenna loop is arranged concentric to and positioned outside of the primary antenna loop adapted to horizontal and vertical wavelengths of a RF transmission at alternate frequencies other than the midband frequency, forming a antenna detector array. Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means o the elements and combinations particularly pointed out in the appended claims.

The "Box-Kite" UHF/VHF Television is an advanced antenna design, and provides improved antenna gain and thus picture quality for analog and digital television. The invention makes good use of the fact that UHF band TV transmission propagate primarily in the horizontal axis with horizontally polarized RF wavefronts balanced and not relative to earth ground, and VHF band transmissions of TV conversely propagate primarily in the vertical axis coupled to earth as the ground plane. Characterized as a 'Hybrid' Horn-Loop design, and using improvements to the antenna detector element, the reflective horn, the Faraday cage, the band pass filter, and the impedance matching transformer, the "Box-Kite" antenna design makes advances in all of the components of an antenna with noticeably improved performance .

To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. Fig. 1A is a top view depicting a vertical cross- section of the detector element of the present invention;

Fig. IB is a front view of the detector element illustrating and open side of a Faraday cage of the present invention. ; Fig. 1C is a side view of the detector element illustrating horizontal elements at a dual intersection of a dual parabolic reflector and depicting a cross-section of the Faraday Cage/Parabolic reflector horn shape of the present invention; Fig. 2 depicts a front view of a conventional UHF TV loop; Fig. 3 is a front view of a rectangular loop of one embodiment of the present invention;

Fig. 4 is a front view of a detector element of one embodiment of the present invention; Fig. 5A is a front view of a helical coil element of one embodiment of the present inven ion;

Fig. 5B is a front view of a multiple element parallel array of one embodiment of the present invention;

Fig. 6 is a plan view of a wire cloth used as a Faraday cage to block off-axis signals of one embodiment of the present invention;

Fig. 7 is a plan view of a modified Faraday Cage reflector of one embodiment of the present invention;

Fig. 8 is an electrical schematic diagram of an impedance matching transformer of the present invention;

Fig. 9 is an electrical schematic of an improved impedance matching transformer of the present invention;

Fig. 10 is an electrical schematic of a center tapped detector element attached to a Faraday cage of the present invention;

Fig. 11 is an overview of the antenna detector of the present invention; and

Fig. 12 is an exploded view of the detector loop, transmission line and matching transformer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the present preferred embodiments of the invention, an examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In accordance with the invention, the present invention includes a directional antenna adapted to receive broadcast signals, the directional antenna including a substantially rectangular primary antenna loop adapted to _ receive a horizontal and vertical polarization of one of a transmission wavefront and waveshape, wherein the primary antenna loop is adapted to minimize dipole wavelength matching at a midband frequency; a non-conductive substrate or insulator, wherein the primary antenna is coupled to the non-conductive substrate and wherein the substrate produces a minimal effect at an operating frequency of said directional antenna; an antenna detector array, the antenna detector array coupled to said directional antenna through the substrate or insulator and positioned in front of a reflective surface at a rear of a parabolic curve, at or near a focal point of the parabolic curve; and at least one secondary antenna loop of different length from the primary antenna loop, whereby the secondary antenna loop is arranged concentric to and positioned outside of the primary antenna loop adapted to horizontal and vertical wavelengths of a RF transmission at alternate frequencies other than the midband frequency, forming a antenna detector array.

Fig. 1A depicts a box-kite antenna 100 with a Faraday cage 110 and detector 120. The dimension of the box is "1" and in one embodiment 1 is equal to 12" or 15" or 18" . Fig. IB is a front view of detector 100 and Fig. 1C is a side cut-away view of the detector 100 showing the Fraday cage/Parabolic horn or curve 110 and the configuration of the detector element 120. A conventional UHF TV loop antenna of 7" in diameter, is shown in Fig. 2, wherein (d = -7") . However, horizontal RF 210 feilo (F_H) engages loop only at R_H + S_x, S₂. Vertically polarized RF field (F_v) 220 engages loop only at T_v 230 + T_v.240 Loop lengths W or 4W total are thus wasted and off axis 45° from proper polarization with the RF field itself .

This problem is overcome with a rectangular loop rather than round shape as shown in Fig.3. This way, the field polarization is coherent and aligned with the detector element. During horizontal induction, the vertical elements act as transmission lines, and conversely during vertical induction, the horizontal elements act as transmission lines. As shown in Fig. 4 the idealized UHF detector element uses a corner tapped V_s center tapped transmission line output. This geometrically and symmetrically matches elements R_H as identical but out of phase. The R_H elements are more important than the T_v 230 and 240 elements, which act as transmissions lines. This is because UHF propagates primarily as horizontally polarized at UHF frequencies. Further, elements R_H 310 may be backed by a parabolic or curved reflector that increases gain of the antenna in the horizontal axis, while leaving vertical induction at unity. The length R_H 310 is chosen at the center of the operational bandwidths wavelength to be : R_H x 2 = l/F_c for half dipole operation.

As shown in Fig. 4, there are several variations on the square detector element with corner tapped transmission line. Fig. 5A depicts a helical coil element increases voltage gain, yet increases source impedance also. Fig. 5B depicts multiple element parallel array couples with multiple elements in parallel via a tuned transmission line (T) . This increases voltage gain while reducing source impedance to output, increasing output power square elements X, Y and Z* could number 1 or more (3)*, each element could be tuned to specific UHF channels for that market. Again R = 1/2F, where F_c = UHF center freq.

As shown n Fig. 6 a simple box shaped sire cloth (%" grid) can used as a Faraday cage to block off axis signals (X = 180°) (Z = 90°), such that the noise floor of the UHF TV signal is greatly attenuated. On axis signals (Y = 0°) are allowed to directly affect and induce detector element (d) . The box is five (5) sided, with the sixth side open to the RF target. Dimensions are 12", 15" and 18" or larger cubed.

As shown in Fig. 7, by using not five (5) sides of a box, but rather three (3) sides, the back side of the Faraday cage can be folded or curved into a dual parabolic reflector. Using the horizontally polarized square coop detector element gives gain or signal boost to the horizontal elements (1+2) , while leaving the vertical elements unaffected to serve as transmission lines. The opening and depth of reflector is 12", 15" or 18" or greater. As shown in Fig. 8 most 300 ohm to 75 ohm impedance matching transformers are wired as shown in Fig. 9.

This setup creates an imbalance to the balanced inputs by reference of the 300 ohm input to DC ground. This causes groundwire affects to horizontally polarized UHF TV signals, by this imbalance. As shown in Fig. 9 by making the detector element 50π's, allow for 6dB of gain in matching 50π to a 75π output. The input winding is center tapped to provide a neutral signal path relative to the detector element for attaching the Faraday cage as depicted in Fig. 10. The detector element itself can be center tapped to attach the Faraday cage as well.

The invention will be further clarified by the following examples, which are intended to be purely exemplary of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the Box-Kite Antenna of the present invention and in construction of this antenna without departing from the scope or spirit of the invention. As an example the shape of the primary loop may be trapezoidal or a parallelogram in nature and continue to provide superior reception to broadcast signals. Furthermore, wires sizes other than the 22 gauge wire may be larger than this dimension. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specifica ion and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A directional anuenna system, suited for television broadcast reception including a detector element or antenna loop, comprising: (a) a primary antenna wire loop, 8" to 10" square, whereby rather than the conventional round loop, adapts to the horizontal and vertical polarization of the Television transmission wavefront or waveshape;

(b) a primary antenna wire loop, 8" to 10" square, whereby the wire itself is very small, less than 22 gauge minimizing dipole wavelength matching at midband;

(c) a primary antenna wire loop, whereby the wire loop itself is mounted on a substrate or insulator which is non- conductive and of little effect at the operating frequency of 50 to 850 MHz maximum;

(d) substrate or insulator which is non- conductive supporting the antenna detector array, is positioned in front of the reflective surface at the rear of the horizontally polarized parabolic curve, at or near focal point of the said parabolic curve; and

(e) a secondary antenna wire loop or loops, of various lengths other than 8" to 10" square, whereby these secondary are arranged concentric to the primary outside square loop, adapts to the horizontal and vertical wavelengths of the RF Television transmission at alternate frequencies other than midband, forming a antenna detector array.

2. A system as in claim 1, of a transmission line, tying the detector elements also called antenna loop or loop(s) together, comprising: (a) said source output transmission line is coupled to the corner of the square loop rather than the center like most conventional round loops, providing symmetry in the Horizontal and Vertical elements of the loop itself, avoiding dissecting the loop at the bottom of the lower horizontal element;

(b) said source output transmission line is coupled directly to matching transformer input or primary coil, at the corner or the overall array, keeping transmission line lengths to a minimum and reducing out of phase wavefront ingress into the array;

(c) whereby said source antenna transmission line is isolated from reflections and ingress by the Faraday cage effect of the reflector horn when off -axis; and (d) a non-reflecting RF load is coupled to said transmission line, in this case the matching transformer.

3. A system as in claim 1 wherein, a TV reception 'HORN' antenna operating over a band of frequencies feeding television RF broadcast signals to said TV antenna system, comprising:

(a) a horizontal planar parabolic curved horn surrounding the detector array element, serving to funnel and concentrate RF signals from the front of the horn; (b) a horizontal planar parabolic curved horn surrounding the detector array element, serving as a Faraday cage to isolate off-axis RF signals not coming from the front of the horn, and effecting the detector element or loop, with ingress of multi-path signals or external interference. Further, the shielding of the detector provides Anti -Noise Design Rejection of all forms Off -Axis Noise & Interference, including a Anti-Refraction Design that Minimizes MultiPath problems m DTV and Ghosting m NTSC, Anti-Spheric Design Reduces Nose & Interference from lightning, geo-magnetic storms, Ionosphere Sources plus Sunspots, SolarFlares and SolarWmds Emissions, and Anti- Fadmg Design Rejects SkyWave & GroundWave variations to signal strength;

(c) a horizontal planar parabolic curved horn surrounding the detector array element, serving as a Faraday cage to isolate off-axis RF signals not coming from the front of the horn, and effecting the transmission line or matching transformer, serving as micro detectors by their very addition to loop length;

(d) a sheet reflector, said sheet reflector being of predetermined geometric shape, aligned with dipole span of the horizontal elements of the wire loop detector element, forming a horizontal planar parabolic curved horn surrounding the detector array element, whose rear reflective surface serves to concentrate RF signals upon only the horizontal axis into the detector element array increasing gain of the horizontally polarized portion of a UHF TV signal, the primary mode of UHF band propagation; and

(e) whereby the Faraday cage whose interior reflective surface serves to collect electromagnetic energy, can be referenced to the balanced UHF horizontal wavefront, which is otherwise not coupled to the earth ground below it, as a vertically polarized VHF TV band wavefront .

4. A system as in claim 2 wherein, the matching transformer between the detector array, transmission line and the TV itself it optimized as follows:

(a) the matching transformer defines the loop impedance as 50 ohms, not 300 ohms, and is wound in a 2:3 turn step up ratio, giving a voltage gain thought the transformer, to it's 75 output secondary, and on to an external TV tuner or front end section itself;

(b) the center tap of the primary is optional to tie to the loop detector array or the earth ground reference of the Faraday reflective cage or remain open and unused in a disabled state by removing a shorting jumper;

(c) a ferrite circulator or transformer core containing magnetized ferrite material, couples the primary of 2 turns to the secondary of 3 turns using a bi- filar wound overlay of the wire coils made of 26 gauge enameled wire;

(d) The primary or input port to the matching transformer is wired directly and balanced to the transmission line tying the detector array together dissecting the lower corner of the square detector loops, with no connection either via AC/DC inductive or capacitate to the secondary or output side of the matching transformer. This forms a balanced to unbalanced conversion in the matching transformer as well as impedance and voltage matching, and 'de-couples' the UHF horizontally polarized from bring being shunted by leakage to the earth- ground plane in most transformers;

(e) a non-reflecting RF load is coupled to said transformer's secondary coil or output port,; (f) said television antenna transmission line is coupled to said transformer's primary coil or input port; and

(g) said ferrite material is resonant to electromagnetic waves at the frequency of said television RF broadcast signals when said ferrite material is nominal operating state.

5. A system as in claim 1 wherein, the detector loop itself is center tapped comprising:

(a) In said Square detector loop as described above, the loop itself maybe center tapped at the opposite corner of the transmission line to the loop and this center-tap used as null -point or ground point reference in a balanced horizontally polarized array, which otherwise has no earth ground reference;

(b) said center-tap to the loop may be tied to a center tap of the matching transformer primary, made to float open or tied to the Faraday Cage / Reflector Horn, in order to create a electrical path for the Faraday shield to an otherwise balanced system of the wire loop with no other apparent neutral; and

(c) said center tap to the loop may be tied to the Faraday cage via a hi-pass coupling capacitor, in order to de-couple any DC static discharge or potential or low frequency AC noise ( 60Hz) from the loop null point at it's center tap.

6. A directional antenna adapted to receive broadcast signals, the directional antenna comprising: a substantially rectangular primary antenna loop adapted to receive a horizontal and vertical polarization of one of a transmission wavefront and waveshape, wherein the primary antenna loop is adapted to minimize dipole wavelength matching at a midband frequency; a non-conductive substrate or insulator, wherein the primary antenna is coupled to the non-conductive substrate and wherein the substrate produces a minimal effect at an operating frequency of said directional antenna; an antenna detector array, the antenna detector array coupled to said directional antenna through the substrate or insulator and positioned in front of a reflective surface at a rear of a parabolic curve, at or near a focal point of the parabolic curve; and at least one secondary antenna loop of different length from the primary antenna loop, whereby the secondary antenna loop is arranged concentric to and positioned outside of the primary antenna loop adapted to horizontal and vertical wavelengths of a RF transmission at alternate frequencies other than the midband frequency, forming a antenna detector array.

7. The directional antenna according claim 1, wherein the primary antenna loop and the secondary antenna loop is a wire loop.

8. The directional antenna according claim 7, wherein the primary antenna wire size to minimize dipole wavelength matching at the midband frequency is less than or equal to 22 gauge.

9. The directional antenna according to claim 8, wherein the primary antenna loop is substantially square.

10. The directional antenna according to claim 9, wherein the square primary antenna loop has a dimension of one of 8" and 10" .

11. The directional antenna according to claim 1, wherein the primary antenna loop is substantially square.

12. The directional antenna according to claim 11, wherein the square primary antenna loop has a dimension of one of 8" and 10" .

13. The directional antenna according to claim 1, wherein the operating frequency of the directional antenna is substantially over the range of 50 to 850 MHZ.

14. The directional antenna according to claim 10, wherein the operating frequency of the directional antenna is substantially over the range of 50 to 850 MHZ.

15. The directional antenna according to claim 14, wherein the parabolic curve is a horizontally polarized parabolic curve.

16. The directional antenna according to claim 14, wherein the at least one secondary antenna wire loop has a length other than one of 8" and 10" .

17. The directional antenna according to claim 1, wherein the parabolic curve is a horizontally polarized parabolic curve.