ZA200206721B

ZA200206721B - An antenna.

Info

Publication number: ZA200206721B
Application number: ZA200206721A
Authority: ZA
Inventors: Anthony Elijah Rabie
Original assignee: Anthony Elijah Rabie
Priority date: 2000-02-26
Filing date: 2002-08-22
Publication date: 2003-04-11

Description

AN ANTENNA

FIELD OF THE INVENTION

This invention relates to an antenna, more particularly, but not exclusively, to a television antenna. -

BACKGROUND TO THE INVENTION

Many different forms of antenna exist for receiving television signals. All antennae have at least one active element, which is connected to the receiver or television set. For internal antennae (i.e. antennae used indoors), the active elements are often stand-alone units, sometimes referred to as "bunny ears".

External antennae usually have additional reflector and carrier elements associated therewith, which may be active elements (i.e. they are electrically connected to the receiver) or may be passive elements (i.e. they are electrically insulated from the receiver). All of the antenna elements are commonly carried on a boom mounted to a pole or other structure. Generally, the boom is of an electrically conductive material and is grounded. The carrier and reflector elements usually enhance the performance of the antenna.

For the most part, active elements are in the form of rods, which may be telescopically extendible, or elongate loops.

OBJECT OF THE INVENTION

|t is the object of this invention to provide an antenna having a particular active * element to enhance the performance of the antenna.

CONFIRMATION COPY

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an antenna which ‘ includes an active antenna element having a generally polygonal-shaped lobe , » with other than four sides. in a preferred embodiment of the invention, the antenna includes a pair of like active antenna elements arranged symmetrically about an antenna axis.

The sides of the lobes of the active antenna elements may be substantially equal in length. In particular, the lobes of the active antenna elements may be generally triangular. Instead, the lobes of the active antenna elements may be generally hexagonal.

The antenna may have a coaxial antenna lead. One of the active antenna elements may be connected to an inner conductor of the coaxial antenna lead and the other of the active antenna elements may be grounded. Then, the antenna may include an inductor, the grounded active antenna element being grounded via the inductor.

The antenna may further include an elongate antenna boom, a longitudinal axis of which defines the antenna axis, the active antenna elements being mounted on the boom transversely thereto and at least one carrier element may be mounted on the boom transversely thereto.

Still further, the antenna may include at ieast one reflector element mounted on the boom in a plane generally perpendicular to the antenna axis.

According to a further aspect of the invention there is provided an antenna which } includes an elongate antenna boom, a longitudinal axis of which defines an antenna 1 25 axis; a plurality of carrier elements mounted on the boom transversely thereto to form an array;

a plurality of reflector elements mounted on the boom in a plane generally perpendicular to the antenna axis to form an array; a pair of like active antenna elements arranged symmetrically about the ) antenna axis and mounted on the boom transversely thereto, one of the active 4 5 antenna elements being connected to an inner conductor of a coaxial antenna lead and the other of the active antenna elements being grounded via an inductor; and in which each antenna element has a polygonal-shaped lobe with other than four sides, the sides being of substantially the same length and the value of the inductance of the inductor when expressed in millihenrys being about the same as the length of a side of the active antenna elements when expressed in millimeters.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings

Figure 1 shows a perspective view of an antenna in accordance with the invention; and

Figure 2 shows a part sectional elevation of part of the antenna of Figure 1. ~~ DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

A television antenna (1) in accordance with the invention is shown in Figure 1.

The antenna (1) has a boom (2) secured to an upright pole (3) by means of a U- bolt (4). The boom (2) defines an antenna axis and a pair of active antenna . elements (5) having lobes (6), (7) is secured to the boom (3) intermediate its ends (8), (9) and transversely thereto. The antenna (1) has a reflector (10), t comprising an array of reflector elements (dipoles) (11) arranged in a plane perpendicular to the boom (2), at the end (9) thereof. A plurality of carrier elements (dipoles) (12) extend intermediate the active elements (5) and end (8)

of the boom (2) to form an array. The carrier elements (12) and reflector elements (11) are active elements and are directly electrically connected to the boom, which is conductive, and the active elements (5), and are not insulated ’ therefrom. - 5 Each lobe (6), (7) of the active elements (5) is constructed from aluminium tubing bent to be hexagonal in shape, sides (13) of the hexagon being of equal length. In this embodiment, each side is approximately 100 mm long. Free ends (15), (16) of the tubing used for the respective lobes (6), (7) extend parallel to each other away from the hexagonal lobe (6), (7).

The free ends (15), (16) of the lobes (6), (7) extend through the sides of a connection box (20) secured to the boom (2) and are secured by clamps (21), (22) to the box (20). A coaxial cable (25), providing an antenna lead, is connected to a television set (not shown) and extends along the pole (3) terminating in the box (20). A quick coupling, shown in Figure 2, allows the inner conductor (30) of the coaxial antenna lead (25) to be connected to one lobe (6) and the outer braiding (31) to be connected to the other lobe (7). The outer braiding (31) is also connected via a 100 mH inductor (32) to the boom (2) in this way grounding the lobe (7).

As shown more clearly in Figure 2, a bracket (34) is provided which extends upwardly from the surface of the box (21) to which it is secured. A pin (35) extends normally from the bracket (34) and is shaped to be insertable centrally into the end of the coaxial cable (25) to abut the inner conductor (30). A pair of spikes (36) are spaced apart from the bracket (34) and shaped to pierce the outer insulation (37) of the coaxial cable (25) and to reach the outer braid (31) but not the inner conductor (30). A clamp (38) is securable over the coaxial cable (25) adjacent to the spikes (36) to force the antenna cable (25) onto the . spikes when secured in position. . The coupling shown provides a quick and effective means for securing the coaxial cable (25) in position without the need for stripping of insulating layers.

The bracket (34) is simply connected to the lobe (6) by a length of insulated wire and the spikes (36) are similarly connected to the lobe (7). v The active elements (5) have been found to provide improved reception of * television signals in the UHF, VHF and VLF range. The active elements (5) has also been found to be effective when used as a stand-alone antenna in indoor applications. The active elements further functions well when retrofitted to existing antennae.

It will be appreciated, however, that many other embodiments of an antenna exist which fall within the scope of the invention. For example, the active elements (5) may have three or more sides and need not be constructed of tubing or rods, but could be cut from a metal piate.

Also, the quick coupling use for the coaxial cable could have any convenient configuration.

Claims

. 1. An antenna which includes an active antenna element having a generally polygonal-shaped lobe with other than four sides.

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2. The antenna as claimed in Claim 1, which includes a pair of like active antenna elements arranged symmetrically about an antenna axis.
3. The antenna as claimed in Claim 2, in which the sides of the lobes of the active antenna elements are substantially equal in length.
4. The antenna as claimed in Claim 3, in which the lobes of the active antenna elements are generally triangular.
5. The antenna as claimed in Claim 3, in which the lobes of the active antenna elements are generally hexagonal.
6. The antenna as claimed in Claim 2, in which one of the active antenna elements is connected to an inner conductor of a coaxial antenna lead and the other of the active antenna elements is grounded.
7. The antenna as claimed in Claim 6, which includes an inductor, the grounded active antenna element being grounded via the inductor.
8. The antenna as claimed in Claim 2, which includes an elongate antenna boom, a longitudinal axis of which defines the antenna axis, the active antenna elements being mounted on the boom transversely thereto; and at least one carrier element mounted on the boom transversely thereto.
9. The antenna as claimed in Claim 8, which includes at least one reflector element mounted on the boom in a plane generally perpendicular to the antenna axis.
10. An antenna which includes : an elongate antenna boom, a longitudinal axis of which defines an J antenna axis; ¢ a plurality of carrier elements mounted on the boom transversely thereto ‘5 to form an array; a plurality of reflector elements mounted on the boom in a plane generally perpendicular to the antenna axis to form an array; a pair of like active antenna elements arranged symmetrically about the antenna axis and mounted on the boom transversely thereto, one of the active antenna elements being connected to an inner conductor of a coaxial antenna lead and the other of the active antenna elements being grounded via an inductor; and in which each antenna element has a polygonal-shaped lobe with other than four sides, the sides being of substantially the same length and the value of the inductance of the inductor when expressed in millihenrys being about the same as the length of a side of the active antenna elements when expressed in millimeters.
11. An antenna substantially as herein described, with reference to Figure 1 of the accompanying diagrammatic drawings. ,