CN201590466U

CN201590466U - High image reject band-pass filter

Info

Publication number: CN201590466U
Application number: CN2010200432163U
Authority: CN
Inventors: 郑宏兴; 刘芬; 王利强; 高凤友; 马兴兵
Original assignee: TIANJIN ENGINEERING NORMAL COLLEGE
Current assignee: TIANJIN ENGINEERING NORMAL COLLEGE; Tianjin University of Technology
Priority date: 2010-01-06
Filing date: 2010-01-06
Publication date: 2010-09-22
Anticipated expiration: 2020-01-06

Abstract

The utility model discloses a band-pass filter with high image reject ability for RF and microwave system fields. The high image reject band-pass filter comprises two resonators; each resonator is composed of two bobby pin arms and is U-shaped, the two resonators are arranged with opening ends opposite to each other, two gaps are respectively positioned between the two resonators, the space of the two gaps is identical, two taps are respectively arranged on the left and right sides of the high image reject band-pass filter, the two taps are respectively connected with the bottoms of the two U-shaped resonators, the signal is input from the left tap to the two resonators and is output from the right tap. The high image reject band-pass filter has compact structure, small size, can flexibly adjust the position of the transmission zero through changing the positions of the taps, according realizes higher image reject and avoids defective coupling.

Description

A kind of high mirror image inhibition zone bandpass filter

Technical field

The utility model belongs to radio frequency, microwave system field, particularly relates to a kind of band pass filter that comprises resonator, can carry out height to useless image signal and suppress.

Background technology

At present, adopt cross coupling structure to make high mirror image inhibition zone bandpass filter, can utilize the cross-couplings between the non-conterminous resonator to produce the transmission zero of improving amplitude fading.But adopting this method to design band pass filter will need at least four resonators, just can reach good attenuation characteristic, and because the resonator that comprises is many, the insertion loss is big.Realize that by the design conventional band-pass filters high mirror image suppresses and hangs down Insertion Loss is possible, for example interdigitated, hair clip type, terminal coupling and cavity configuration etc.Wherein, cavity filter can realize that high mirror image suppresses, but often very heavy, is difficult to carry out integrated with microwave integrated circuit.Terminal coupling and hair clip type filter are the most commonly used at microwave frequency band, but size is still very big, and need a lot of resonators; These type band pass filters show bad second harmonic signal composition in addition.For example roll up in " a kind of design of novel little band Hairpin band pass filter " literary composition of delivering on the 5th phase at " the microwave journal " the 22nd that microwave journal periodical publisher publishes in October, 2006 by people such as Chen Shiyong, for obtain with outside be higher than novel hair clip type filter that the inhibition ability of 30dB proposed at least more than five rank, make size very big, be unfavorable for installing.

Summary of the invention

In order to overcome the deficiencies in the prior art, the utility model provides a kind of and has adopted minimum coupling unit, utilized the cramped construction between the resonator, make the band pass filter size reduce, and can realize, reach desirable mirror image inhibition level the transmission zero better controlled.

The technical scheme that its technical problem that solves the utility model adopts is: high mirror image inhibition zone bandpass filter comprises two resonators, described resonator is made of two hair clip arms, one is long and the other is short for two described hair clip arms, described resonator is " U " font, two described resonators are staggered relatively according to " U " font openend, two gaps lay respectively between two described resonators, two described gap clearance equate, be located on the same line than the long hair jig arm than in bob jig arm and another described resonator in the described resonator, two taps lay respectively at the left side and the right side of described high mirror image inhibition zone bandpass filter, two taps are connected with the bottom of two " U " font resonators respectively, signal is imported from the left side tap, through two described resonators, export from the right side tap.

The size in two described gaps can influence the coupling coefficient between the resonator, and the frequency at transmission zero place is introduced in the position decision of two described taps.

The beneficial effects of the utility model are, owing to adopted minimum resonator, compact conformation, size are little, can regulate the position of transmission zero neatly by changing tap position simultaneously, thereby realize that higher mirror image suppresses, and not have bad coupling.

Description of drawings

Fig. 1 is the structural representation of high mirror image inhibition zone bandpass filter.

Fig. 2 is the circuit diagram of high mirror image inhibition zone bandpass filter.

Fig. 3 is the domain of high mirror image inhibition zone bandpass filter.

Fig. 4 (a) is parameter S 11 analogous diagram of high mirror image inhibition zone bandpass filter, and Fig. 4 (b) is parameter S 21 analogous diagram of high mirror image inhibition zone bandpass filter.

Among the figure: 1 and 5 are tap, and 2,4,6 and 8 is the hair clip arm, and 3 and 7 is the gap of resonator, and 9 and 10 is the hair clip type resonator.

Embodiment

Below in conjunction with accompanying drawing, the utility model is further described.

In Fig. 1, tap 1 is positioned at the left end of filter; 2,4,6,8 is the hair clip arm, and wherein hair clip arm 2 is identical with the length of hair clip arm 6, and hair clip arm 4 is identical with the length of hair clip arm 8, and hair clip arm 8 length are greater than hair clip arm 2, and hair clip arm 4 length are greater than hair clip arm 6; The gap 3 of resonator is between hair clip arm 2 and hair clip arm 4, and the gap 7 of resonator is between hair clip arm 8 and hair clip arm 6, and the gap 3 of resonator and 7 clearance distances equate; Tap 5 is positioned at the right-hand member of filter; Formed left side hair clip type resonator 9 by hair clip arm 2 and hair clip arm 8, formed right side hair clip type resonator 10 by hair clip arm 4 and hair clip arm 6, resonator 9 resonator 10 all are " U " font, two resonators are staggered relatively according to " U " font openend, hair clip arm 2 and hair clip arm 4 are located on the same line, and hair clip arm 8 and hair clip arm 6 are located on the same line; Tap 1 and tap 5 lay respectively at the bottom of " U " font, and signal is from tap 1 end input, and through resonator 9, the electric coupling effect by the gap enters resonator 10, and exports from tap 5 ends.It is pointed out that the

gap

3 and 7 between resonator 9 resonator 10, its size has influenced the coupling coefficient between the resonator; The frequency at transmission zero place is introduced in tap 1 and the decision of 5 positions, and the transmission zero place frequency shown in Fig. 4 (b) is respectively 4.3GHz and 4.92GHz.

Fig. 2 is the circuit diagram of high mirror image inhibition zone bandpass filter, Term1 and Term2 are two terminate loads, TL1 to TL10 is a microstrip line, Bend1, Bend2, Bend3, Bend4 is little band bending line, Tee1 and Tee2 are little band splitters, Gap1 and Gap2 are little band gaps, wherein little band bending line Bend1, microstrip line TL2 and microstrip line TL4 form hair clip arm 2, little band bending line Bend3, microstrip line TL6 and microstrip line TL8 form hair clip arm 4, little band bending line Bend4, microstrip line TL7 and microstrip line TL9 form hair clip arm 6, little band bending line Bend2, microstrip line TL3 and microstrip line TL5 form hair clip arm 8.High mirror image band pass filter is made up of five parts, that is: microstrip line TL1 and microstrip line TL10 are respectively tap 1 and tap 5; The resonator of forming to microstrip line TL5, little band bending line Bend1, little band bending line Bend2 and little band splitter Tee1 by microstrip line TL2 9; The resonator of forming to microstrip line TL9, little band bending line Bend3, little band bending line Bend4 and little band splitter Tee2 by microstrip line TL6 10; Gap of forming by little band gap Gap1 3 and the gap of forming by little band gap Gap2 7; By the terminate load that Term1 and Term2 form, its resistance is desirable 50 ohm, and the end of Term1 and the end of Term2 all are connected to signal ground.Resonator 9 is positioned at the left side of filter, resonator 10 is positioned at the right side of filter, resonator 9 resonator 10 all are " U " font, two resonators are staggered relatively according to " U " font openend, hair clip arm 2 and hair clip arm 4 are positioned at same horizontal level, hair clip arm 8 and hair clip arm 6 are positioned at same horizontal level, and gap 3 is between hair clip arm 2 and hair clip arm 4, and gap 7 is between hair clip arm 8 and hair clip arm 6.Signal adds from left side input tap 1, through resonator 9 resonator 10, from right side output tap 5 outputs.

Fig. 3 is the domain of high mirror image inhibition zone bandpass filter, and tap 1 is divided into hair clip arm 2 and hair clip arm 8 two parts with resonator 9, and tap 5 is divided into hair clip arm 4 and hair clip arm 6 two parts with resonator 10.Hair clip arm 2 and hair clip arm 6 length all are 5.8mm, and hair clip arm 4 and hair clip arm 8 length all are 6.7mm; Gap 3 initial values between hair clip arm 2 and the hair clip arm 4 can be set at 0.1mm, and gap 7 initial values between hair clip arm 6 and the hair clip arm 8 are set at 0.1mm equally.The dielectric constant of making the printed board of band pass filter is 10.2, and sheet metal thickness is 0.65mm, and copper thickness is 0.035mm.

With reference to figure 4 (a) and Fig. 4 (b), the passband of band pass filter is that 4.52GHz is to 4.65GHz, centre frequency is 4.58GHz, near two pairing frequency 4.3GHz of transmission zero and 4.92GHz, have outside the good band above 45dB and suppress, the return loss of filter is greater than 15dB, and has the second harmonic that is lower than 10dB.

Claims

1. one kind high mirror image inhibition zone bandpass filter, comprise the resonator of forming by two hair clip arms, the resonator of two hair clip arm formations is " U " font, it is characterized in that: it comprises two described resonators, two described resonators are staggered relatively according to " U " font openend, two gaps lay respectively between two described resonators, two taps lay respectively at the left side and the right side of described high mirror image inhibition zone bandpass filter, two taps are connected with the bottom of two " U " font resonators respectively, signal is imported from the left side tap, through two described resonators, export from the right side tap.

2. high mirror image inhibition zone bandpass filter according to claim 1 is characterized in that, described resonator comprises long described hair clip arm and short described hair clip arm.

3. high mirror image inhibition zone bandpass filter according to claim 2, it is characterized in that, constitute described hair clip arm short in described hair clip arm long in the described resonator of described high mirror image inhibition zone bandpass filter and another described resonator and be located on the same line, constitute that long described hair clip arm is located on the same line in described hair clip arm short in the described resonator of described high mirror image inhibition zone bandpass filter and another described resonator; In described resonator in long described hair clip arm and another described resonator long described hair clip arm lengths equate, in described resonator in short described hair clip arm and another described resonator short described hair clip arm lengths equate.

4. high mirror image inhibition zone bandpass filter according to claim 1 is characterized in that, two described gap clearance of two described resonators equate.