CN2600979Y

CN2600979Y - Anti-interference receiving antenna

Info

Publication number: CN2600979Y
Application number: CN 03228943
Authority: CN
Inventors: 李宏杰; 黄纪刚; 李玉琪
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-19
Filing date: 2003-02-19
Publication date: 2004-01-21
Anticipated expiration: 2013-02-19

Abstract

An interference-proof receiving antenna belongs to the antenna of receiver within VHF and UHF wave band, which is used to make the antenna acquire strong interference-proof performance, high receiving sensitivity, convenient use and easy for promotion. The utility model is characterized in that a single ring antenna A#-[1] is adopted and one end is connected with a grounding variable capacity C#-[1], and the other end is connected with a variable capacity C#-[2] and a grounding transmission line transformer L#-[1], and connected and input to a resonance coil L#-[2], L#-[3] and L#-[4] of a three-level screw filter LB; each coil is connected with a grounding capacitance C#-[3], C#-[4] and C#-[5], and this filter LB is connected with a receiver via BNC cable head; the transmission line transformer L#-[1] can adopt SYV-50-3 cable, the length of VHF wave band adopts 200mm, composing the impedance ratio 4 to 1 and change the 200 omega impedance to 50 omega. This receiving antenna with narrow band and large attenuation slope can be operated under the condition of severe electromagnetic environment reliably.

Description

The anti-interference reception antenna

Technical field: the utility model belongs to the antenna equipment of VHF/UHF frequency range inner receiver.

Background technology: normally adopt whip antenna as reception antenna, but along with the deterioration of electromagnetic environment, especially in the strong jamming location, whiplike reception antenna manifests very big problem.Conventional receiver front end is the broadband, and the whip antenna band is wideer, and situations such as clutter interference, strong signal blocking, receiver third order intermodulation interference have a strong impact on the receiver operate as normal, even make communication disruption.For example, on the high mountain that antenna stands in great numbers, concentrate in this type of location many equipments such as the high-power FM broadcast transmitter of 10KW, television broadcasting transmitter and beeper transmitter, electromagnetic environment is very abominable, make VHF hand intercom (158MHz frequency, 2W transmitting power) the tens of meters distances of only communicating by letter, signal almost completely blocks.1.8GHz GSM mobile handset also get clogged and no signal: once adopt and associate antenna to the method that adds filter between the receiver, but still existing problems: as adopting the multiple coil filter, squareness factor is better, the far-end high reject signal is suppressed, increase along with the raising of squareness factor but insert loss, influence actual reception sensitivity.As adopt single-stage λ/4 coaxial resonant cavity filters, the insertion loss is very little, and squareness factor is poor, and the far-end high reject signal is difficult to meet the demands.So the selection of filter parameter is a key, and the layman is difficult to carry out.

Summary of the invention:

The purpose of this utility model provides a kind of single-frequency and puts special-purpose reception antenna, has strong anti-interference performance, receiving sensitivity height, characteristics such as easy to use, to solve problems of the prior art.

For achieving the above object, take following technical scheme:

Adopt the monocycle antenna, the one end connects a variable capacitance tuning with loop antenna, the other end connects the variable capacitance with the loop antenna coupling, connect through line transformer and three chamber screw-filters, change its helical resonator into the capacitive load resonator, each resonator two end all has electric capacity, and an end is a capacitor C, and the other end is tuning screw rod.

The beneficial effect of technical solutions of the utility model:

When avoiding many rings between the endless belt line proximity effect influence efficient, employing monocycle mode, endless belt antenna length L ≈ λ/4, the efficiency curve peaking also becomes steady; Increase the endless belt width and use copper belt, reduce the loss of endless belt line resistance as far as possible; Cause this endless belt antenna efficiency more than 90%.

2. adopt the suitable match point of endless belt antenna, loop antenna input impedance value is 200 Ω, and the reactance slope of curve is significantly improved, and frequency sensitivity is stronger; For with 50 Ω filter match, after impedance conversion in 4: 1, just in time 200 Ω are matched to 50 Ω by line transformer.

3. because all there are response point in endless belt antenna and common screw-filter on third harmonic frequencies, for avoiding two device spurious responses stack problem on the third harmonic frequencies, change helical resonator into the capacitive load resonator, the effect of loading capacitance, not only shorten resonator length, and third harmonic frequencies is put spurious response move to the appropriate location, can effectively avoid the stack of two device spurious responses, improve and suppress the far-end interference capability.

Adopt reception antenna of the present utility model, owing to be that arrowband, attenuation slope are big, in that electromagnetic environment is very abominable as the aforementioned, on the high mountain that antenna stands in great numbers, adopt the 158MHz frequency equally, through overtesting, from under the mountain to the mountain, rice surplus the drop 300, signal of communication can reach 5 minutes, can better satisfy instructions for use.

Description of drawings:

Fig. 1 is a schematic circuit:

Fig. 2 is the product structure schematic diagram.

Embodiment: with reference to description of drawings embodiment.

As shown in Figure 1, loop antenna A ₁An end connect ground connection variable capacitance C ₁, C ₁Be the loop antenna tuning capacity, the other end connects variable capacitance C ₂, C ₂Be the loop antenna matching capacitance, variable capacitance C ₂Connect ground connection line transformer L ₁, do impedance conversion, impedance ratio 4: 1 transforms to the resonance coil L that 50 Ω are input to three grades of screw-filter LB with impedance 200 Ω ₂, L ₃, L ₄, each coil is the C of series connection earth capacitance successively respectively ₃, C ₄, C ₅, this filter LB is connected with receiver.As shown in Figure 2, loop antenna A ₁Be connected and fixed by bolt 3 and casing 1 (ground plate) insulation by polyethylene dielectric 2; Variable capacitance C ₁One end connecting ring antenna A ₁, the other end shell 1 of meeting sb. at the airport; Variable capacitance C ₂One end and loop antenna A ₁Connect another termination line transformer L ₁, L ₁Can adopt the SYV-50-3 cable, VHF frequency range length 200mm, constituting impedance ratio is 4: 1, and impedance transformer is connected with three grades of screw-filter LB, and filter LB connects antenna output cable head BNC and links to each other with receiver.

Claims

1. the anti-interference reception antenna is provided with filter at antenna between the receiver, it is characterized in that adopting loop antenna (A ₁), an end connects ground connection variable capacitance (C ₁), the other end connects variable capacitance (C ₂), and connect ground connection line transformer (L ₁), connect the resonance coil (L that is input to three grades of screw-filter LB ₂), (L ₃), (L ₄), each coil is connected in series ground capacity (C successively respectively ₃), (C ₄), (C ₅), this filter LB links to each other with receiver by BNC connector.

2. by the described anti-interference reception antenna of claim 1, it is characterized in that line transformer (L ₁), can adopt the SYV-50-3 cable, VHF frequency range length is got 200mm, and constituting impedance ratio is 4: 1, and 200 Ω transform to 50 Ω with impedance.