Measurement of Measurement of Efficiency Efficiency

for power combinerfor power combiner

May 99 Through property for 6*4 array power combiner 2

Circuit TopologyCircuit Topology

• Use 50 Ohms transmision line to replace the MMICs• Waveguide environment• Slotline-to-microstrip transition• From 2 trays to 6 trays, different schemes are tested.

( The 6 metal cards are always mounted, but circuit tray number varies.)

May 99 Through property for 6*4 array power combiner 3

Impedance of bond wireImpedance of bond wire

Bond wire

• Total A, B, C, D 4 connection for each path• For each connection, 6*0.001” gold wire• From 1 -> 1, 1.4 Ohm• From 3 -> 3, 0.8 Ohm• From 5 -> 5, 1.4 Ohm• From Gnd -> Gnd, 0.2 Ohm

1

33

5 5

1

D

CB

A

GndGnd

May 99 Through property for 6*4 array power combiner 4

• S11 < - 11 dB• S21 vary from - 1.1 dB to

- 1.5 dB

S parameters:

S parameters of 2-Trays combinerS parameters of 2-Trays combiner

• Low insertion loss• Low return loss • The best among all

Comparison :

-30

-25

-20

-15

-10

-5

0

-30

-25

-20

-15

-10

-5

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Through Measurement for 2 Trays

Frequency, GHz

May 99 Through property for 6*4 array power combiner 5

• S11 < - 8 dB• S21 vary from - 1.3 dB to

- 2.4dB

S parameters:

S parameters of 6-Trays combinerS parameters of 6-Trays combiner

• Low insertion loss, but higher than 2 and 4 trays

• Return loss is higher than 2 and 4 trays too

Comparison :

-30

-25

-20

-15

-10

-5

0

-30

-25

-20

-15

-10

-5

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Through Measurement for 6 Trays

Frequency, GHz

May 99 Through property for 6*4 array power combiner 6

Over-sided 8-Trays combinerOver-sided 8-Trays combiner

• 8-Tray power-combiner is tested• To hold more circuit trays, an over-sided wave-

guide is used• The taper wave-guide has showed low

reflection, and could match well with WR-94 wave-guide

Oversized taperWave-guide

Oversized taperWave-guide

WR-94Wave-guide

WR-94Wave-guide

8-TrayPower-Combiner

May 99 Through property for 6*4 array power combiner 7

Waveguide Taper StructureWaveguide Taper Structure

• Linear Taper Transition• Oversized Waveguide Opening (1.12 in. x 0.9 in.)• 4 in. Transition Each Side

Oversized Waveguide Environment Oversized Waveguide Environment to Accommodate the 8-Tray Systemto Accommodate the 8-Tray System

-70

-60

-50

-40

-30

-20

-10

0

10

8.5 9 9.5 10 10.5 11 11.5 12

Ret

urn

/ Ins

ertio

n Lo

ss, d

B

Frequency, GHz

S21

S11

OversizedOpening

StandardOpening

May 99 Through property for 6*4 array power combiner 8

• S11 < - 7.6 dB• S21 vary from - 1.1 dB to

- 2.5 dB

S parameters:

S parameters of 8-Trays combinerS parameters of 8-Trays combiner

• Insertion loss is higher

Comparison :

-30

-25

-20

-15

-10

-5

0

-30

-25

-20

-15

-10

-5

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Through Measurement for 8 Trays

Frequency, GHz

May 99 Through property for 6*4 array power combiner 9

How the loss is calculated?How the loss is calculated?

• The loss is evaluated by the ratio of the output power over the power which could be transmitted forward.

221

211

| |1 | |

load

in reflection

P SLossP P S

Power Combiner

inP

reflectPloadP

No incident wave at Port2

lossP (Radiation & conduction loss)

in reflection loss loadP P P P

May 99 Through property for 6*4 array power combiner 10

How the efficiency is calculated?How the efficiency is calculated?

• Li = Lo , and is half of the total loss ( in dB).• The Efficiency is calculated on one side antenna array, and is Li

or Lo on percent.

N-way Combiner System

Splitter CombinerPia

G

Poa

Pdca

Li Lo

Pi Po( )( ) ( )

2*100%

Loss dBLi dB Lo dB

Efficiency Li

May 99 Through property for 6*4 array power combiner 11

Loss of 2-Trays combinerLoss of 2-Trays combiner

-10

-8

-6

-4

-2

0

-10

-8

-6

-4

-2

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Loss for 2-Trays combinerS21 MAG [dB] Loss[dB]

Frequency, GHz

• S21 has ripples due to reflection of antenna

S parameters:

• Loss is lower than S21• Insertion loss is almost

constant over all frequency• Average loss is –1.30 dB• Average Efficiency is 86.1%

Loss :

May 99 Through property for 6*4 array power combiner 12

• S21 is lower than 2-trays

S parameters:

Loss of 6-Trays combinerLoss of 6-Trays combiner

• Loss is more than 2-Trays

• Average loss is –1.30 dB

• Average Efficiency is 86.1%

Loss :

-10

-8

-6

-4

-2

0

-10

-8

-6

-4

-2

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Loss for 6-Trays combinerS21 MAG [dB] Loss[dB]

Frequency, GHz

May 99 Through property for 6*4 array power combiner 13

Loss of 8-Trays combinerLoss of 8-Trays combiner

-10

-8

-6

-4

-2

0

-10

-8

-6

-4

-2

0

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0

Loss of 8-Trays combinerS21[dB] Loss[dB]

Frequency, GHz

• S21 has ripples due to reflection of antenna

S parameters:

• Average loss is –1.34 dB

• Average Efficiency is 85.7%

Loss :

May 99 Through property for 6*4 array power combiner 14

SummarySummary

• The power combiner’s efficiency keeps at constant around 86% when the active device increase from 8 to 32 pieces. 0

20

40

60

80

100

-5

-4

-3

-2

-1

0

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0

Efficiency & Loss vs. Number of Amplifiers

Number of Amplifiers