Balun, unun, balbal

Hjemmelavet 1:1 strømbalun som anvender en torusformet kerne og koaksialkabel.

En Balun, unun eller balbal anvendes ved audiofrekvenser og radiofrekvenser til elektriske signalkredsløb (inkl. datakredsløb).

En bredbåndet balun med ferritkerner blev første gang beskrevet i radioamatørlitteraturen i 1964 af radioamatøren Richard H. Turrin, W2IMU. Ordet unun blev opfundet af radioamatøren Jerry Sevick, W2FMI.

Baluner, ununer og balbaler har en eller flere af disse formål:

omsætte mellem et balanceret kredsløb og et ubalanceret (unbalanced) kredsløb (balun).
- Ubalancerede kredsløb er fx ubalancerede elektriske transmissionslinjer (fx koaksialkabler) og radioantenner med ubalanceret tilkobling (fx discone-antenne og kvartbølge groundplane antenne).
- Balancerede kredsløb er fx balancerede elektriske transmissionslinjer (fx hønsestigekabel) og radioantenner med balanceret tilkobling (fx dipolantenne og bikonisk antenne).
tilpasse impedansen mellem to kredsløb. (både balun, unun og balbal kan benyttes til det)

Herudover kan baluner, ununer eller balbaler have andre egenskaber:

Isolere elektrisk mellem de to tilkoblingssider (galvanisk isolation).
Virke for et smalt bånd af frekvenser - eller virke for et bredt bånd af frekvenser (bredbånd).

Hvis man ikke anvender baluner, ununer eller balbaler på den rette måde, især med radiosendere, kan man risikere at:

Sende signaler mellem koaksialkablets skærm - og stel/jord (med risiko for at forstyrre andre) - og/eller opsamle uønskede signaler mellem koaksialkablets skærm - og stel/jord.
Sende ubalancerede signaler ind i balancerede transmissionslinjer; bieffekt - der sendes også signaler mellem signallederen og stel/jord, hvilket forårsager uønsket udstråling. Modtage balancerede signaler i en ubalancerede transmissionslinje, hvilket som bieffekt vil modtage uønskede signaler, da common-mode støj (uønskede signaler) ikke kan udfases.

Balancerede og ubalancerede signaler

En balanceret transmissionslinje har signal på begge ledere, det ene signal i fase og det andet i modfase i forhold til stel eller jord - mens en ubalanceret transmissionslinje har den ene leder (skærmen) forbundet til stel eller jord i den ene eller begge ender.

Typisk formidles ubalancerede elektriske signaler via koaksialkabler, hvor stellederen (yderlederen) helt omslutter signallederen (inderlederen). Formålet med denne omslutning er både at holde formidlede signaler inde i transmissionslinjen - og hindre udefra kommende signaler at overlejre de formidlede signaler.

Transmissionslinjetransformator

En transmissionslinjetransformator er en transformator, der benytter transmissionslinjer som en del af designet. Der findes flere typer:

Ruthroff-transformator (impedans 1:4) - fra en ubalanceret transmissionslinje til en anden (unun). Ruthroff-transformatoren blev offentliggjort i en artikel af C.L. Ruthroff i 1959.
Guanella-transformator (impedans 1:4) - fra en balanceret transmissionslinje til en anden (balbal). Guanella-transformatoren blev offentliggjort i en artikel af George Guanella i 1944.

Kilder/referencer

↑ Richard H. Turrin, W2IMU, "Broad-Band Balun Transformers", QST, August 1964, pages 33-35. http://www.arrl.org/qst
↑ CQ April 1994 pp. 26-46, More On The 1:1 Balun BY JERRY SEVICK*, W2FMI Citat: "...Baluns have taken on a more significant role in the past few decades with the advent of solid-state transceivers and Class B linear amplifiers, which have unbalanced outputs...R. Turrin, W2IMU — 1964. The first presentation in the amateur radio literature on 1:1 baluns using ferrite cores was by Turrin in 1964.10 Turrin, who was a colleague of Ruthroff at Bell Labs...", backup
↑ 2003, Understanding, Building, and Using Baiuns and Ununs. Theory and Practical Designs for the Experimenter. Jerry Sevick, W2FMI. ISBN 0-943016-24-X Citat: "...The "Unun," a word I coined several years ago, came about because there was no acceptable term for a device matching unbalanced impedance to unbalanced impedance, and it became quite tedious to continuously type the whole expression. In discussing this device on the air, I found many called it a U-nun—obviously the right terminology is Un-un..."
1 2 pacarc.org: Antenna & Transmatch Evaluation Field Manual. Official Guide for the Strange Antenna Challenge Citat: "...Baluns are actually a small family of devices: balun, balbal, or unun. These all refer to the whether you desire to move between balanced (ladder line) to unbalanced (coax) transmission line (bal-un), between balanced and balanced line (bal-bal), or between unbalanced and unbalanced line (un-un). I will usually refer to all of these with the generic term “balun.”...The most common baluns are 1:1 (one to one) and 4:1. Baluns are a form of transformer, either changing voltage or current by a given ratio...Properly terminating balanced line is important...You may also place a “bal-bal” at the antenna feedpoint. This will adjust the impedance...Connecting your balanced line to a single coax transmission line will require a balun...", backup
↑ QEX Mar/April 2005: Designing Wide-band Transformers for HF and VHF Power Amplifiers Citat: "...The three forms of transformers that are encountered, unbalanced-to-unbalanced (unun), balanced-to-balanced (balbal), and balanced-to-unbalanced (balun), are used in various combinations to accomplish the desired goals...[Illustrationer:] Fig 22—Three-conductor twisted-wire transformer configurations...", backup
↑ k5tra.net: Transmission-Line Transformers, backup
↑ February 2004, highfrequencyelectronics.com: A Simplified Analysis of the Broadband TransmissionLine Transformer. By Jerry Sevick. Bell Laboratories (Retired) and Consultant, backup
↑ Ruthroff, C.L., "Some Broad-Band Transformers", Proc IRE, Vol 47, August 1959, pp. 1337-1342.
↑ Guanella, G., "Novel Matching Systems for High Frequencies", Brown-Boveri Review, Vol 31, Sep 1944, pp.327-329.

Eksterne henvisninger

Jan 06, 2015, mwrf.com: Sorting through Balun Confusion

[1] Richard H. Turrin, W2IMU, "Broad-Band Balun Transformers", QST, August 1964, pages 33-35. http://www.arrl.org/qst

[2] CQ April 1994 pp. 26-46, More On The 1:1 Balun BY JERRY SEVICK*, W2FMI Citat: "...Baluns have taken on a more significant role in the past few decades with the advent of solid-state transceivers and Class B linear amplifiers, which have unbalanced outputs...R. Turrin, W2IMU — 1964. The first presentation in the amateur radio literature on 1:1 baluns using ferrite cores was by Turrin in 1964.10 Turrin, who was a colleague of Ruthroff at Bell Labs...", backup

[3] 2003, Understanding, Building, and Using Baiuns and Ununs. Theory and Practical Designs for the Experimenter. Jerry Sevick, W2FMI. ISBN 0-943016-24-X Citat: "...The "Unun," a word I coined several years ago, came about because there was no acceptable term for a device matching unbalanced impedance to unbalanced impedance, and it became quite tedious to continuously type the whole expression. In discussing this device on the air, I found many called it a U-nun—obviously the right terminology is Un-un..."

[pacarc-4] 1 2 pacarc.org: Antenna & Transmatch Evaluation Field Manual. Official Guide for the Strange Antenna Challenge Citat: "...Baluns are actually a small family of devices: balun, balbal, or unun. These all refer to the whether you desire to move between balanced (ladder line) to unbalanced (coax) transmission line (bal-un), between balanced and balanced line (bal-bal), or between unbalanced and unbalanced line (un-un). I will usually refer to all of these with the generic term “balun.”...The most common baluns are 1:1 (one to one) and 4:1. Baluns are a form of transformer, either changing voltage or current by a given ratio...Properly terminating balanced line is important...You may also place a “bal-bal” at the antenna feedpoint. This will adjust the impedance...Connecting your balanced line to a single coax transmission line will require a balun...", backup

[QEX-5] QEX Mar/April 2005: Designing Wide-band Transformers for HF and VHF Power Amplifiers Citat: "...The three forms of transformers that are encountered, unbalanced-to-unbalanced (unun), balanced-to-balanced (balbal), and balanced-to-unbalanced (balun), are used in various combinations to accomplish the desired goals...[Illustrationer:] Fig 22—Three-conductor twisted-wire transformer configurations...", backup

[6] 5tra.net: Transmission-Line Transformers, backup

[7] February 2004, highfrequencyelectronics.com: A Simplified Analysis of the Broadband TransmissionLine Transformer. By Jerry Sevick. Bell Laboratories (Retired) and Consultant, backup

[8] Ruthroff, C.L., "Some Broad-Band Transformers", Proc IRE, Vol 47, August 1959, pp. 1337-1342.

[9] Guanella, G., "Novel Matching Systems for High Frequencies", Brown-Boveri Review, Vol 31, Sep 1944, pp.327-329.