FI118362B - Antenna matching transformer e.g. for VHF/UHF antennas, consists of a coil core and a pair cable wound around the coil core - Google Patents

Abstract

Matching transformer comprises of a coil structure with a coil core (43) of ferrite material and a pair cable (44) wound around it. The coil core (43) is made of a powdery material having a specified permeability, and the distance between the conductors of the cable pair is fitted to achieve wave impedance. The mutual reactance of the conductors and the permeability of the coil core, enable the antenna to be tuned to the desired frequency automatically without a special tuning element. Independent claims are also included for the following: (a) antenna.

Description

118362

BROADBAND ANTENNA ADAPTER

The present invention relates to a broadband antenna adapter for an antenna having a radiator, an adapter and an interface unit for connecting the antenna to the antenna cable.

5

Broadband antennas for the VHF range, e.g. 30 MHz upwards, currently use complex multi-capacitors, coils, and other components to adapt the antenna radiator to operate over a wide frequency range, typically as a pre-1o signal in the 30 to 90 MHz range. .

Such fitting units are relatively large in size and the component joints are susceptible to damage, particularly to antennas used in moving vehicles. In addition, adapters may require gear-shifting with mechanical switches to tune the antenna to operate in the desired frequency range. Tuning causes delays, making it impossible to perform tuning, for example, when using a hopping frequency.

The object of the present invention is to provide a completely new type of broadband antenna adapter which is very simple and compact in structure, and which automatically tunes the antenna into the desired frequency range without any tuning parts. The adapter of the invention consists of a powdery substance. a circular coil core and a pair of wires wrapped around it, with a mutual reactance (mutual inductance and pattern: 25 capacitance) between the conductors, which allows the adapter together with the coil core to adapt the antenna part to the desired frequency.

· · *: **: In detail, the features of the adaptation unit according to the invention are prevented by the appended claims.

30

The adapter according to the invention is compact, which makes the antenna structure smaller and lighter compared to the known solutions. In addition, the adapter tunes the *. * 'Antenna completely automatically, eliminating the need for any manual tuning.

* * * v: Furthermore, the adapter according to the invention is very reliable and is not sensitive to mechanical stress such as vibration of rolling stock. According to the invention. ! ·. • An antenna with an adapter can be used to transmit at high power (· 100W, if necessary).

• · · * · 2 118362

In the following, the invention will be explained in more detail by way of example with reference to the accompanying drawing, in which Figure 5 shows a broadband antenna with an adapter according to the invention in partial section and Fig. 2 in more detail.

Fig. 1 shows, for example, a broadband antenna 1 suitable for vehicle use in the VHF range 30 to 90 MHz having a whip-shaped radiator 2, typically a quarter of the center frequency wavelength, its attachment part 3 and an adapter 4 according to the invention is adapted to operate in the frequency range. The adapter has a housing 41 with an electrical connection 15 disposed thereon and at the bottom of which is a connector 42 for connecting the unit to the radio unit by an antenna cable for transmitting and receiving VHF band.

The electrical circuit in the adapter according to the invention consists of an annular glass core 43 which is a powdered iron alloy. For example, a pair of cables 44 are wound around the core 43, for example five turns divided evenly around the core to form a toroidal structure. The conductors 45, 46 of the cable pair 44 are connected to the antenna connector 42 and the radiator 2. The adapter operates to generate a mutual reactance between the twisted-pair conductors, whereby the wires together with the \ v 25 coil cores automatically tune the radiator to the desired frequency. provides the impedance required by the antenna connection, typically "1 to 50 Ω.

• ·

It will be apparent to one skilled in the art that various embodiments of the invention are not limited to the example above, but may vary within the scope of the following claims. The antenna can be mounted on its base, e.g., on a vehicle roof, by means of fasteners (not shown) in the housing 41. With the adapter according to the invention, the antenna can also be adapted to a wider frequency range than the above.

···:: 35 ··· • · · · · · · · · · ·

Claims (3)

118362 A broadband antenna adapter (1) for a VHF / UHF range antenna having an antenna emitter (2) and an adapter (4) for adjusting the antenna to a desired frequency, the adapter having a coil structure having a coil core (43) and a twisted pair (44), characterized in that the adapter is for transmitting and receiving, that the coil core (43) is a powdery material, and that by means of the mutual reactance of the conductors and coil core of the cable pair (44), the antenna is automatically adjusted without a specific tuning element. Adapter according to claim 1, characterized in that the coil core is annular. 15 Adapter according to claim 1, characterized in that the cable pair is twisted around the core in one plane and the number of turns is less than ten, preferably 4-6. • M · 1 2 3 • · 1 • · • • • • • • • • • • • • • • • • • • • • • • • • • • · • • • • 1 • · · • 1 • · M »* · *« · • f * · · 2 • · • «118362