GB1562904A - Horns - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HORNS (71) We, THE MARCONI COMPANY LIMITED, a British Company of Marconi House, New Street, Chelmsford, Essex, CM I 1 PL. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed. to be particularly described in and by the following statement:- This invention relates to pyramidal horns and seeks to provide improved such horns.

According to this invention a pyramidal horn is provided in which the internal cross-sectional dimensions in both the E and H planes increase along the length of the horn from input to output in accordance with a function of distance along the horn axis which approximates to a sine squared function.

In one practical example of horn in accordance with the present invention said function is given by where

s 1 2xs - - -sin L 2n L and where s =distance along the horn axis b(s) =tapered horn height at point s b1 =height of horn throat b2 =height of horn mouth L =total length of tapered section The internal surfaces of the horn may be smooth or corrugated or a combination of smooth and corrugated.

The invention is illustrated in and further described with reference to the drawings accompanying the provisional specification in which, Figure 1 is a section in plan of one horn in accordance with the present invention Figure 2 is a section in elevation of the horn of Figure 1, and Figure 3 is a view looking into the throat of the horn of Figures 1 and 2.

Referring to the drawings, the horn illustrated has E-plane and H-plane dimensions which in each case follow a continuously varying curve along the main axis I of the guide. In fact that curvature function approximates to a sine squared function (sin2 x). Any section transverse to the main axis I will be rectangular, but with this example over no part of the length of the horn does its E-plane and Hplane dimensions vary linearly.

The horn may be fabricated of sheet metal or electro-formed as known per se.

The dimensions of this particular horn are as follows:- length 246 mm minimum E-plane dimension e 7 mm maximum E-plane dimension E 69 mm minimum H-plane dimension h 67.26 mm maximum H-plane dimension H 215 mm The curvature function is chosen to provide a relatively small rate of change at the throat end and at the aperture end of the horn. In this specific case the curvature function in both the E-plane and the H-plane is given by

where s 1 27rs y=---sin L 2n L and where s =distance along the horn axis b(s) =tapered horn height at point s b, height of horn throat b2 =height of horn mouth L =total length of tapered section.

It is believed that the horn described above has, compared for example to a conventional pyramidal horn, relatively low throat reflections providing satisfactory broad band capabilities, and a relatively well defined relatively constant, phase centre over the operating band.

WHAT WE CLAIM IS: 1. A pyramidal horn in which the internal cross-sectional dimensions in both the E and H planes increase along the length of the horn from input to output in accordance with a function of distance along the horn axis which approximates to a sine squared function.

2. A horn as claimed in Claim 1 and wherein said function is given by

where s 1 2ns Y=-- -sin L 2rr L and where s =distance along the horn axis b(s) =tapered horn height at point s b, =height of horn throat b2 =height of horn mouth L =total length of tapered section 3. A horn as claimed in Claim I or 2 and wherein the internal surfaces of the horn are smooth.

4. A horn as claimed in Claim 1 or 2 and wherein the internal surfaces of the horn are corrugated at least in part.

5. A pyramidal horn substantially as herein described with reference to the drawings accompanying the provisional specification.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. The curvature function is chosen to provide a relatively small rate of change at the throat end and at the aperture end of the horn. In this specific case the curvature function in both the E-plane and the H-plane is given by where s 1 27rs y=---sin L 2n L and where s =distance along the horn axis b(s) =tapered horn height at point s b, height of horn throat b2 =height of horn mouth L =total length of tapered section. It is believed that the horn described above has, compared for example to a conventional pyramidal horn, relatively low throat reflections providing satisfactory broad band capabilities, and a relatively well defined relatively constant, phase centre over the operating band. WHAT WE CLAIM IS:

1. A pyramidal horn in which the internal cross-sectional dimensions in both the E and H planes increase along the length of the horn from input to output in accordance with a function of distance along the horn axis which approximates to a sine squared function.

2. A horn as claimed in Claim 1 and wherein said function is given by

where s 1 2ns Y=-- -sin L 2rr L and where s =distance along the horn axis b(s) =tapered horn height at point s b, =height of horn throat b2 =height of horn mouth L =total length of tapered section

3. A horn as claimed in Claim I or 2 and wherein the internal surfaces of the horn are smooth.

4. A horn as claimed in Claim 1 or 2 and wherein the internal surfaces of the horn are corrugated at least in part.

5. A pyramidal horn substantially as herein described with reference to the drawings accompanying the provisional specification.