ELEKTROMAGNETIKA

Kelompok 3

The Smith Chart

by

Fandy Septian NugrohoMuhammad HabibiePhilips LawrenceZesyara Melati Auzriani Ghaniyya

ELEKTROMAGNETIKA

The Smith Chart

Review

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-12 (p. 281)The Transmission Line Calculator, commonly referred to as the Smitha Chart.

Smith ChartSumbu Impedansi riil

Sumbu Impedansi Imajiner

Satu putaran setengah panjang gelombang

K. A. ConnorRPI ECSE Department

Mendekati Generator

Menjauhi Generator

Lingkaran konstant koefisien refleksi

Skala dalam Panjang Gelombang

IMPEDANCE MATCHING

Matching impedance yaitu upaya untuk mencocokkan impedansi input (Zin) dengan impedansi karakteristik (Z0).

Tujuannya: Menghasilkan VSWR = 1 Mentransmisikan daya tanpa dipantulkan Efisiensi transmisi optimum

Quarter Wave Transformer

Ketika beban merupakan beban riil (tidak ada komponen reaktif),maka quarter-wave matching network dapat digunakan, di mana:

Untuk seperempat panjang gelombang, l = /2 tan (l) = , sehingga

Matching with The Smith Chart

 

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-23 (p. 297)The objective of a matching network is to move to the center of the Smith Chart. The values shown are for Example 6.6.

Didapat jarak dari 0,076λ sampai 0,0188λ yaitu 0,112λ

Agar Zin = Z0, maka zin = (1 + j2) – j2 = 1 = z0

(matched!!) Maka ditambahkan reaktansi = -j100 Ω Hasil keseluruhan terlihat di figure 6.24b

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-24 (p. 298)(a) A 50- T-line terminated in an 11+ j25 load for Example 6.6. (b) T-line with tuning capacitor added at the appropriate distance from the load.

Drill 6.14Suppose a 50- T-line is terminated in a 100- load. Determine the required impedance of a quarter-wave matching section of T-line

Admittance of Shunt Stub

AdmitansiYL = 1 / ZL

Dalam hubung pararel, Ytot = YL1 + YL2

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-25 (p. 299)(a) Admittance relationship to impedance. (b) Adding shunt elements using admittances.

Dalam smith chart, yL adalah pencerminan zL terhadap pusat chart

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-26 (p. 300)Finding normalized admittance with a Smith Chart.

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-27 (p. 301)(a) A shorted T-line stub. (b) Smith Chart view of zin and yin

for d = /8.

Untuk shunt stub, pergerakan zin dan yin di keliling chart Shorted shunt stub pergerakan yin clockwise dari 0.25λ (figure

6-27) Open ended shunt stub pergerakan yin clockwise dari 0λ

Langkah-langkah: Plot zL dan yL dalam smith chart. (zL = ) Buat lingkaran Putar zL clockwise sepanjang lingkaran sampai memotong

lingkaran 1 (apa saja) dan didapat yd. Jarak antara yL dan

yd adalah panjang d. jika shunt stub short circuit, pergerakan yL dari 0,25λ

clockwise sampai jika open ended stub circuit, pergerakan yL dari 0 λ

clockwise sampai ytot = yd + yl = 1 + j0 = 1 = y0

(matched!!)

Contoh 6.7 Buatlah matching shorted shunt stub network dengan =

50 Ω saat 20 – j55 Ω load.

Jawab zL = = 0,22 + j0,5 Ω Plot yL dan gerakkan sampai 1 + j2 (dapat yd ) Gerakkan yl (shunt stub) sampai 1 - j2

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-28bc (p. 302) (b) Adding shunt admittances. (c) Using the Smith Chart to find through line and stub lengths. Values on the chart apply to Example 6.7.

Contoh soal Problem 6.34

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-29a (p. 303)(a) The generic layout of the open-ended shunt-stub matching network.

Contoh 6.8 Buatlah matching open ended shunt stub network dengan

= 50 Ω saat 150 + j100 Ω load

jawab zL = = 3 + j2 Ω Plot yL dan gerakkan sampai 1 + j1,6 (dapat yd ) Gerakkan yl (shunt stub) sampai 1 – j1,6

Fundamentals of Electromagnetics With Engineering Applications by Stuart M. WentworthCopyright © 2005 by John Wiley & Sons. All rights reserved.

Figure 6-29b (p. 304)(b) Smith Chart solution to Example 6.8.

Contoh soal Problem 6.35