Runbo Ma

Design of Compact Differential Dual-Frequency Antenna With Stacked Patches

A compact differential dual-frequency antenna with stacked configuration is described. Compared with the conventional stacked dual frequency antenna, the radiating element with a half guided wavelength is distributed on two layers and connected through via holes, thus the dimension of the antenna is reduced effectively. In order to improve the bandwidth at the first resonant frequency (f1), a reflecting board is introduced and connected with the ground plane through three via holes. As a result, a new resonant frequency closing to f1 can be excited and the bandwidth at fx is enhanced. Both differential antennas with and without the reflecting board are fabricated and measured. The realized antennas have a compact size of 15 mm × 15 mm, which equals to 0.23¿1 × 0.23¿1 (¿1, the guided wavelength at f1). Experimental results show that the proposed antenna can operate at 2.4 GHz and 5.2 GHz bands. Good agreement between the simulated and measured results is obtained.

Ultra-Wideband Differential Wide-Slot Antenna With Improved Radiation Patterns and Gain

The UWB systems need the antenna with the same radiation pattern and the stable gain in the whole frequency range. In this communication a compact ultra-wideband differential wide-slot antenna (DWSA) with the improved radiation pattern and gain is proposed. By truncating the corners of the ground plane, the current distribution in it becomes more ordered and the radiation performance of the proposed DWSA in the upper frequency band is effectively improved. Further, one strip line is loaded in the ground plane along the symmetric line in order to strengthen the virtual ground and reduce the influence of asymmetry factor brought by the processing error. The measured results show, the fabricated DWSA presents a -10 dB impedance bandwidth of 133.1% (from 2.49 to 12.41 GHz). Moreover, in the whole band, the antenna basically keeps the same radiation pattern and the gain is over 1.3 dBi. The measured results are in agreement with the simulated results.

Angle-Based Chipless RFID Tag With High Capacity and Insensitivity to Polarization

This paper presents a novel angle-based chipless radio frequency identification (RFID) tag with high capacity that is polarization-independent. Its scatterer is designed to be V-shaped. It encodes data using the space angle between two arms of the V-shape and is identified by measuring the scattered field in two orthogonal polarization directions. Even if it is tilted, the tag can be identified. The advantage of angle-based tag is that every element can encode three-bit data. This is helpful to get higher capacity. Also, for different codes of one element, the proposed tag uses the same spectrum. This is beneficial to improve the efficiency of the spectrum. First, the tag using the uniform impedance resonator (UIR) is designed. Then, the UIR chipless tag is reformed as stepped impedance resonator (SIR) tag to suppress the second harmonic. The realized tags operate in the frequency range 1.83-2.15 GHz and the identification errors are less than 3.9°. Every element of the realized tags can carry 3 bits of coding information.

Calibrating an Arbitrary Test Fixture for a Symmetric Device by Three Measurements

In this paper, a general solution of calibrating a microwave test fixture for a symmetric device is deduced from the cascading network relation, and it exposes the probability and condition of calibrating an arbitrary test fixture for a symmetric device by three measurements, which is less than the times of measurements in the thru-reflect-line (TRL) method. The scattering parameters of the test fixture and the embedded symmetric device can be determined by measurements of a thru, a line, and the symmetric device. Furthermore, the method is analyzed and verified by simulation and measurement. The analysis indicates that the presented method is suitable for determining the calibrated S-parameters of a symmetric device under test (DUT).

Design of Compact Frequency-Tuned Microstrip Balun

In this letter, a compact frequency-tuned microstrip balun with a ring structure is proposed. By tuning the capacitance of varactor, the operating frequency of the balun can be tuned continuously. Also, by arranging the two loops on two layers, the difficulty in process caused by narrow gap can be avoided. Meanwhile, by introducing the lumped capacitors, the dimension of the balun is reduced greatly. The measured results indicate that the balun can operate at 620-1020 MHz when the voltage of varactor changes from 4 to 16 V. The phase difference of the two balanced ports is 180° ± 7°, and the amplitude difference is less than 0.8 dB. The realized balun has a dimension of 19.6 × 16.8 mm², equal to λ₀/25 × λ₀/29 (λ₀, the wavelength in vacuum at 620 MHz).

A Novel Differential Dual-Band Bandpass Filter Based on Stepped-Impedance Double-Sided Parallel-Strip Line

Abstract A novel differential dual-band bandpass filter based on a stepped-impedance double-sided parallel-strip line is proposed in this article. In order to suppress the common-mode signal, an H-shaped ground plane is inserted. The simulated and measured results show that the proposed filter operated at 2.4 GHz and 5.8 GHz with the insertion losses of 3.2 dB and 3.5 dB, respectively. Also, the common-mode signal is suppressed to below −30 dB from 1 GHz to 7.5 GHz.

Compact dual-frequency linear antenna with partial ground plane

In order to meet the need of multiband and antenna-in-package (AiP), a compact dual-frequency antenna with a partial ground and linear structure is proposed, optimised and realised. The proposed antenna was designed at 2.4 GHz and 5.8 GHz bands for WLAN applications. The total size of the antenna is 20 mm × 20 mm, equals to 0.27 λg1 × 0.27 λg1 and 0.65 λg2 × 0.65 λg2 (λg1, λg2 are the microstrip (with ground) guiding wavelengths at 2.4 GHz and 5.8 GHz) or 0.15 λ01 × 0.15 λ01 and 0.38 λ02 × 0.38 λ02 (λ01, λ02 are the wavelengths in the atmosphere at 2.4 GHz and 5.8 GHz). Also, omnidirectional radiation characteristics in the desired bands can be obtained.

Design of CPW-fed tri-band coplanar slot antenna

In this paper, a tri-band coplanar slot antenna fed by a coplanar waveguide is designed and it contains multiple slot segments with different lengths and widths between the patch and the ground conductors. By analyzing the effect of each slot segment, it is found that the tri-band antenna can be realized by adjusting the size of each slot segment properly. The proposed structure is used to design a 2.4/3.8/5.8 GHz tri-band antenna with the size of 29 mm×40 mm. The simulated results indicate the designed antenna operates in the required three bands, which have the bandwidths (reflection coefficient< −10dB) of 260 MHz, 240 MHz and 150 MHz, the peak gains of 2 dBi, 3.1 dBi and 2.7 dBi, respectively.

Chipless RFID tag based on space angle information

This paper presents a novel chipless radio frequency identification (RFID) tag that encodes data based on space angle information. The radiating unit of the proposed tag has the obvious character of the space angle. Compared with that based on the time domain reflectometry and spectral signature, the chipless tags based on space angle information can obtain the larger encoding capacity. Also, the proposed tag is identified by the complex scattered field in two orthogonal polarization directions.

Compact dual-band dipole antenna fed by a coplanar waveguide

A compact dual-band dipole antenna fed by a coplanar waveguide for wireless communication is presented in this paper. The dual-band antenna consists of a long dipole and a short dipole, which were designed for operation at the lower and upper bands, respectively. The miniaturization is achieved by meandering slits in the long dipole. The simulated results show that the antenna can operate at 2.44 GHz and 5.18 GHz. In addition, omnidirectional radiation patterns are achieved at two operating bands.