TRL Calibration Technique for Asymmetrical 2-Port and 3-Port Devices (II)

  • Cheng, Jui-Ching (PI)

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details

Abstract

The wide-spread use of mobile phones and wireless data network, microwave circuits fabricated on printed circuit board (PCB) are getting more and more popular. To measure the S-parameters of the microwave circuits on PCB, vector network analyzer (VNA) are always used. Adapters are required to connect VNAs to these PCBs. As frequency gets higher, the adapter’s performance gets worse and affects the measurement result. To measure the real characteristics of the circuit, TRL calibration technique is proposed. It can effectively compute the true S-parameters of the device under test (DUT) from the measure data of the thru, reflect and line calibration circuits. However, there is one fundamental limitation inherent in the formulation of TRL technique. That is, the two ports must be the same. Devices such as impedance transformers and microstrip-to-CPW transitions can never be derived by TRL technique. To overcome this limitation, in this proposal we present a modified TRL procedure that can measure asymmetrical 2-port devices. This technique features the use of the original TRL technique two times on two sets of calibration kits of the two different ports. Then, from the derived error matrices, the true S-parameters of the asymmetrical 2-port devices can be computed. Detailed formulation of the original TRL technique is derived. The modified TRL procedure for asymmetrical 2-port devices is presented. Preliminary measured result of a microstrip-to-rectangular waveguide transition is shown. Good agreement is achieved. Using the result of the TRL formulation, a TRL procedure for 3-port device is also presented. In the first-year project, we found the original 3-port measurement technique can only be applied to symmetric 3-port devices. Therefore, in the second year, we propose a arbitrary 3-port measurement technique utilizing 2-port TRL calibration. Moreover, we also propose a symmetrical 4-port measurement technique utilizing 2-port TRL calibration. Note that the two proposed technique still are limited to reciprocal devices.

Project IDs

Project ID:PB9912-1049
External Project ID:NSC99-2221-E182-067
StatusFinished
Effective start/end date01/08/1031/07/11

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