Vertical antenna with stub cancellation means

Vertical antenna including a vertical radiator having a height of three-half wavelengths, a cancellation stub electrically connected to the vertical radiator three-quarters wavelength upward from a feed point at the base of the vertical radiator and extending downwardly one-quarter wavelength and upwardly one-half wavelength from the electrical connecting point of the vertical radiator, an insulation member mounted in a mounting post and supporting the base of the vertical radiator, quarter wavelength radials extending outwardly in the same plane and at right angles to the vertical radiator from the mounting post, and a transmission line connected between the feed point at the base of the vertical radiator and the radials. The gain of the vertical antenna is theoretically 3.2 db over a half wavelength dipole antenna. The vertical antenna is particularly lended to operation in the VHF spectrum and above.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to an antenna, and more 
particularly, pertains to a vertical antenna. 
2. Description of the Prior Art 
Those concerned with antennas have long recognized the need for a vertical 
antenna of manageable physical size yielding a desirable gain. The present 
invention fullfills this need. 
In the field of vertical antennas, especially VHF and UHF antennas, it has 
been a general practice to utilize phase reversal stubs or self-cancelling 
coaxial sections making instantaneous current flow take the same direction 
along the entire vertical radiator or along as much of the radiator as 
possible. The phase reversal stubs have been unsatisfactory in that the 
vertical radiator has to be broken with insulating material at or near the 
inner current antinodes. Since the inner current antinodes are high 
voltage points, losses are apt to be severe, especially in damp weather 
and even with the best insulating materials available. Another objection 
is the weight of the insulators as the phasing reversal stubs have to be 
self-supporting tubing or rod, or encompassed within self-supporting 
tubing or rod. A further objection has to do with the additional 
manufacturing steps involved in manufacturing vertical antennas with the 
phase reversal stubs including the additional manufacturing expense. 
Phase reversal sections can also be quarter wave closed transmission line 
stubs. The stubs provide that currents in adjacent radiating sections will 
be in phase with no major or minor high angle lobes. Other phase reversal 
sections can be in the form of coaxial sections which are mechanically 
connected to the vertical antenna and results in a system which is 
electrically and mechanically complicated. A further type of phase 
reversal section is different lengths of transmission lines 
interconnecting a number of vertical dipoles together. 
One prior art antenna utilizes an extended double zepp section which has 
been published in a majority of the electrical and antenna handbooks for 
at least over the last half century. This antenna spaces out the high 
current points on two five-eighths wavelength collinear radiators in order 
to approach a gain figure of three collinear half wave elements. The 
vertical radiator is split in only one place at a low voltage point and a 
phase reversal stub is utilized which is one-eighth wavelength long. The 
antenna appears to be an electrical equivalent of a quarter wave stub 
along where the feed line is tapped for lowest SWR and which is a 
variation of the old J-match. 
The present invention provides a vertical antenna that overcomes all the 
disadvantages of the prior art vertical antennas and provides a realizable 
gain which is theoretically greater than comparable vertical antennnas. 
SUMMARY OF THE INVENTION 
The purpose of the present invention is to provide a vertical antenna which 
exhibits realizable gain over a supportable height of the vertical 
antenna. 
According to one embodiment of the present invention, there is provided a 
vertical antenna including a vertical radiator having a height of 
three-half wavelengths, a cancellation stub electrically connected to the 
vertical radiator three-quarters wavelength upward from a feed point at 
the base of the vertical radiator and extending vertically downward 
one-quarter wavelength and vertically upward one-half wavelength from the 
electrical connecting point of the vertical radiator, an insulation member 
supporting the base of the vertical radiator, quarter wavelength radials 
extending outwardly in the same plane and at right angles to the vertical 
radiator from the insulation member, and a transmission line connected 
between the feed point at the base of the vertical radiator and the 
radials. 
One significant aspect and feature of the present invention is a vertical 
antenna of realizable height and having an attractive gain figure. The 
vertical antenna performs with equal or better gain than other vertical 
antennas of comparable height and physical size. 
Having briefly described an embodiment of the present invention, it is a 
principal object hereof to provide a vertical antenna for practical 
operation on frequencies above ten megahertz. Particularly, the vertical 
antenna is lended in operation to the twenty-seven megahertz Citizens 
Radio Service Band, fifty megahertz and above including the six meter, and 
the two meter amateur bands, and UHF and VHF frequencies. The vertical 
antenna lends itself to utilization by military, commercial, professional, 
and hobbyists including amateur radio operators. 
An object of the present invention is to provide a vertical antenna which 
provides realizable gain for reasonable height. The vertical antenna of 
the present invention provides approximately 3.2 db gain over a half 
wavelength dipole antenna while yet being only three-half wavelengths in 
vertical height. 
Another object of the present invention is to provide a vertical antenna 
which is physically self-supporting and structurally strong. The vertical 
antenna of the present invention is a continuous electrical vertical 
radiator. The electrical vertical radiator is not broken with any 
insulators or any other coupling paraphernalia such as in the prior art 
vertical antennas. Also, the cancellation stub electrically affixes and is 
supported adjacent and substantially parallel to the vertical radiator. 
A further object of the present invention is to provide a vertical antenna 
having a cancellation stub which is electrically connected to the 
electrical vertical radiator of the vertical antenna, is supported by the 
electrical vertical radiator, and is substantially parallel to the 
electrical vertical radiator of the antenna. 
An additional object of the present invention is to provide a vertical 
antenna which is aesthetically pleasing to the eyes of the beholder, of 
minimal physical structure so as to be unnoticeable and neighborhood 
compatible. This is especially important in view of new zoning laws by 
governments regarding placement of antennas. This vertical antenna 
particularly lends itself to installation in condominiums and other 
suburban developments where outdoor antennas are usually disallowed as the 
antenna is of such reasonable height so as to be unnoticeable to the 
average viewer.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1, which illustrates a vertical plan view of a vertical antenna, the 
present invention, shows the electrical vertical radiator consisting of 
four sections of metal tubing 16, 20, 32, and 36 telescoped and 
frictionally engaged forming electrical vertical radiator where the bottom 
first tube 16 is supported by a support center tubular insulator member 
12. The center insulator 12 such as fiberglass or TEFLON is supported by a 
metal tubular support post 14. A first tube 16 telescopes into the tubular 
center insulator 12 and is secured thereto with a self-tapping sheet metal 
screw 18. The top of the first tube 16 is slotted as illustrated. A second 
tube 20 telescopes into the first tube 16 and is secured thereto with a 
stainless steel compression type hose clamp 22. A cancellation stub 24 
including an electrically short horizontal member 24a, a right angle 
curvature bend 24b, a quarter wavelength section 24c, a 180 degree 
curvature bend 24d, and a half wavelength upwardly extending vertical 
section 24e protrudes through two opposing holes in the second tube 20 not 
illustrated for purposes of clarity located approximately three-quarters 
wavelength from the base 58 of the first tube 16 of the vertical antenna 
10 and is secured therein by a self-tapping sheet metal screw 30 at an 
orthogonal angle to the horizontal member 24a of the cancellation stub 24. 
An upper insulating stand-off block 28 having a large and small diameter 
holes and a lower insulating stand-off block 26 having a large diameter 
and two small diameter holes and composed of a quarter inch polyethylene 
strips stand off and insulate the cancellation stub 24 from the second 
tube 20. The particular placement of the position of the insulator 
stand-off members 26 and 28 is not critical. The insulating stand-off 
members 26 and 28 have appropriately sized holes to accommodate the second 
tube 20 and the diameter of the cancellation stub 24. A third tube 32 
telescopes into the slotted end of the second tube 20 and is secured 
thereto with a small stainless steel compression type hose clamp 34. A 
fourth tube 36 telescopes into the top of the third tube and is secured 
thereto with a self-tapping sheet metal screw 38. A suitable cap 40 such 
as polyethylene secures onto the top of the fourth tube 36 such as by 
friction engagement for aesthetics and protection from the environmental 
elements. A plurality of radials, 42 and 46, by way of example and for 
purposes of illustration only, mounts through the support post 14 in 
substantially a planar configuration, perpendicular to the vertical 
radiator, and are affixed thereto with screws 44 and 48. A L-shaped 
bracket 50 secures to the mounting post 14 with a screw 52 and supports a 
female coaxial connector 54 such as a SO-239. An impedance matching and dc 
grounding coil 56 connects between the screw 18 and the screw 44. The 
center conductor of the coaxial connector 54 connects to the screw 18 with 
a wire 60 and the outer conductor of the coaxial connector 54 electrically 
connects through the support post 14 to the plurality of radials 42 and 
46. In the alternative, transmission feed line can directly connect 
between the screws 18 and 44. 
PREFERRED MODE OF OPERATION 
The vertical antenna 10 of the present invention is constructed and 
assembled in one of the following manners. The unslotted end of the first 
tube 16 is telescoped into the end of the center tubular insulator 12 of 
the support post 14. A No. 10 screw 18 is passed through the lug not 
illustrated in the figure from the end of the wire 60 of the coaxial 
connector 54 and through the aligned holes between the center insulator 12 
and the first tube 16. The slotted end of the second tube 20 is passed 
through the large diameter hole in the lower insulator 26 of the 
cancellation stub 24 which has already been bent into the shape as 
illustrated in FIG. 1. The horizontal end 24a of the cancellation stub 24 
is pushed through the opposing holes in the second tube 20 and secured 
thereto with the No. 10 screw 30. The upper insulating stand-off member 28 
is passed down and over the second tube and the upper portion of the 
cancellation stub 24e and frictionally engages thereto. Physical placement 
of the insulators 26 and 28 is not critical except for achieving 
structural support. The cancellation stub 24 is spaced a small fraction of 
a wavelength such as one-thirtieth wavelength or less from the second tube 
20. The third tube 32 is telescoped into the slotted end of the second 
tube 20 and secured thereto with the compression clamp 34. The fourth tube 
36 is slid into the third tube and secured thereto with a No. 6 screw 38. 
The plurality of radials 42 and 46 are passed through holes just above the 
coaxial connector 54 supported on the L-bracket 50 and secured thereto 
with No. 10 screws at right angles thereto. The impedance matching coil 56 
connects between the screw 18 and No. 10 screw 44. The vertical antenna 10 
can be secured to any suitable mounting mast such as a standard TV mast. 
The vertical antenna 10 is fed with suitable transmission line such as 
fifty ohm coaxial cable transmission feed line. 
The exact height of the vertical antenna is determined by the resonating 
frequency or midband resonance, and lengthening and shortening of the 
antenna at the two clamps 22 and 32 lowers or raises the resonance 
frequency respectively. Resonance is determined by checking the VSWR of 
the vertical antenna. 
The vertical antenna 10, while illustrated as being composed of four 
tubular sections 16, 20, 32, and 36, can be one electrical conductor such 
as a vertical tower, a vertical electrical rod, or a straight wire. The 
cancellation stub electrically connects to the tower, rod, or electrical 
wire, and is suitably supported adjacent thereto. 
The vertical antenna 10 lends itself to any frequency of operation. In the 
lower HF frequencies, the vertical antenna can be a tower. In the higher 
HF frequencies, the vertical antenna can be a tower or vertical electrical 
rod. In the frequencies of thirty megahertz and above, the vertical 
antenna 10 is easily lended to a small self-supporting structure and is 
particularly lended in operation to the low band six meter, two meter, 
high band, one and one-quarter meter, and UHF frequencies. The vertical 
antenna 10 can be particularly used in military applications, commercial 
applications, professional applications, and amateur radio applications. 
By way of example and for purposes of illustration only, the vertical 
antenna has an overall vertical height of 275.6 cm for two meters, a 
radial length of 49.4 cm, and the horizontal portion of the cancellation 
stub connects 107.2 cm from the base of the vertical antenna 10. The four 
tubular sections 16, 20, 32, and 36 can be 0.75" O.D. .times.3' end 
slotted tube, 0.625" O.D. .times.3' end slotted tube, 0.50" O.D. .times.2' 
tube, and 0.375" O.D. .times.3' tube. The cancellation stub 24 and radials 
42 and 46 can be 3/16" rod. The impedance matching coil can be 4-5 turns 
of No. 14 wire having a one inch diameter. 
The exact lengths of the height of the vertical radiator, the length of the 
cancellation stub, and the length of the radials are dependent upon the 
type of material utilized. 
Various modifications can be made to the vertical antenna of the present 
invention without departing from the apparent scope thereof.