US3082421A - Compensated antenna - Google Patents

Description

March 19, 1963 N. SHYHALLA 3,082,421

- COMPENSATED ANTENNA Filed Jan. 26, 1960 NICHOLAS SHYHALLA m f w 3,082,421 COMPENdATEB ANTENNA Nicholas Shyhalla, Niagara Falls, N.Y., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed .ian. 26, 196i Ser. No. 4,821 4 {Zia-rims. {61. 343-114) The present invention relates to antennas and more particularly to antennas of such a configuration that it will be decoupled from its mount.

When it is attempted to mount directional antennas on missiles or other airframes, distortion of the antenna patterns is usually encountered. This results from the fact that the airframe itself may be a reasonably eflicient antenna and the airframe, considered as an antenna, is coupled to the directional antenna. This tends to make the resulting antenna pattern resemble that of the airframe rather than the intended directional pattern. The result is that at very high frequencies (VHF) (30 to 300 megacycles) small direction-finding antennas become impractical, especially for horizontally-polarized radiation, since in this case the missile pattern becomes more serious.

An object of the present invention is the provision of an antenna configuration which will cancel the coupling between the antenna and its mount.

Another object is to provide an antenna which will cancel the coupling between the antenna and its mount, thus making it possible to detect polarized radiated signals.

Other objects and many of the attendant adantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein there is shown a preferred embodiment of the invention.

As shown, the antenna assembly comprises four closed loops 1! 11, 12, and 13 positioned symmetrically about an axis 14 in an airframe or missile 20. Each of the four loops is connected across terminals 16 and 18. Lead wires 19 are for connecting the antenna to a receiver, not shown.

The areas of loops and 11 and their radial distances from the missile longitudinal axis are adjusted to give the same degree of coupling as between them and the missile frame 20 as exists between the pair of loops 12 and 13 and the missile frame 20.

In use, the antenna could be mounted in a missile or airframe for receiving VHF command radio signals. For a missile that is symmetrical about the longitudinal axis, the antenna assembly is also symmetrical about this axis. The VHF command radio signals to be received by the antenna are polarized in the horizontal plane and, in this plane, the radiation pattern obtained with the loop antenna described is a figure eight with nulls in alignment with the missile longitudinal axis. The properties of the loop antenna and the theory upon which these properties depend are set forth on pages 907-908 of Electronic and Radio Engineering, by Frederick Emmons Terman, 4th Edition, 1955, McGraw-l-Iill Book Company. Left-right horizontally polarized command signals are picked up only by horizontal loops 12 and 13, the vertical loops 1t) and 11 picking up essentially no radiation directly. The output of loops 12 and 13 is a left-right error signal which 3,8Z,4Zl Patented Mar. 19, 1963 is zero for straight ahead and is proportional to the difference in the time of arrival of the radiating signal at loops l2 and 13. This error signal is fed to a control circuit, not shown, for controlling the flight of an aircraft or missile. All four loops 10, 11, 12 and 13 are adjusted to give the same degree of coupling between them and the missile frame. The interconnection of the loops makes these separate couplings cancel each other.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination with an airframe, a very high frequency receiving antenna assembly mounted in said airframe, said antenna assembly comprising a plurality of closed loops mounted in a horizontal plane, a plurality of closed loops mounted in a vertical plane, the areas and positions with respect to said airframe of said vertically and horizontally mounted loops being adjusted to give the same degree of coupling between said loops and said airframe, and means connecting said loops to make the couplings from said vertical loops cancel the couplings from said horizontal loops.

2. In a very high frequency directional radio receiving antenna system adapted to be mounted in an aircraft: the combination comprising a first pair of closed loops mounted in a horizontal plane, a second pair of closed loops mounted in a vertical plane, said first and second pair of loops being positioned relative to each other to give the same degree of coupling between them and the aircraft, said first and second pair of loops being interconnected to thereby cause the couplings between said missile and said loops to cancel.

3. In a missile, a very high frequency directional radio receiving antenna mounted in said missile, said receiving antenna comprising a first pair of closed loops symmetrically mounted in a horizontal plane about the center line of said missile, a second pair of closed loops symmetrically mounted in a vertical plane about the center line of said missile, said first and second pairs of loops being connected in parallel to effectively decouple said antenna from said missile.

4. In a missile, a very high frequency receiving antenna mounted within the airframe of said missile for receiving horizontally polarized radio signals, said receiving antenna comprising first, second, third, and fourth closed loops, the areas of said loops and positions with respect to said airframe being such as to provide the same degree of coupling between said loops and said airframe, said first and third loops lying in the horizontal plane, said second and fourth loops being perpendicular to said first and third loops, first and second electrical connector means to connect all of said loops in parallel such that the couplings between said loops and said airframe are effectively cancelled.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. IN COMBINATION WITH AN AIRFRAME, A VERY HIGH FREQUENCY RECEIVING ANTENNA ASSEMBLY MOUNTED IN SAID AIRFRAME, SAID ANTENNA ASSEMBLY COMPRISING A PLURALITY OF CLOSED LOOPS MOUNTED IN A HORIZONTAL PLANE, A PLURALITY OF CLOSED LOOPS MOUNTED IN A VERTICAL PLANE, THE AREAS AND POSITIONS WITH RESPECT TO SAID AIRFRAME OF SAID VERTICALLY AND HORIZONTALLY MOUNTED LOOPS BEING ADJUSTED TO GIVE THE SAME DEGREE OF COUPLING BETWEEN SAID LOOPS AND SAID AIRFRAME, AND MEANS CONNECTING SAID LOOPS TO MAKE THE COUPLINGS FROM SAID VERTICAL LOOPS CANCEL THE COUPLINGS FROM SAID HORIZONTAL LOOPS.

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