A compact open-loop resonator filter with a wide stopband response

This paper presents a new class of microstrip slow-wave open-loop resonator filter with reduced size and improved stopband characteristics. A comprehensive treatment of both resonator ends loaded with triangular and rectangular shapes is described, leading to the invention of a microstrip slow-wave open-loop resonator. A four-resonator bandpass filter is designed at the operating frequency about 2 GHz, bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q-factor. The proposed filter is not only compact size due to the slow-wave effect but also has a wider upper stopband resulting from the dispersion effect. The filter design of this type will be described in detail. The experimental results are demonstrated and discussed.     

Wideband constant beamwidth coplanar waveguide‐fed slot antennas using metallic strip loadings and a widened tuning stub with shaped reflectors

Sectored antennas with wideband operation for wireless communication systems are presented. The proposed configurations are based on a coplanar waveguide fed slot antenna using metallic strip loadings and a widened tuning stub above various reflector shapes. By shaping the reflector, noticeable enhancements in both unidirectional radiation pattern and beamwidth can be achieved while maintaining the simple fabrication and installation. Based on the results obtained, three sector antennas covering 72°, 90°, and 120° beamwidths suitable for five, four, and three sectors, respectively, have been proposed and designed. The simple structural configurations, low cost, and ease of half power beamwidth control of the proposed antennas make the design very attractive for practical implementation. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Microstrip Slow‐Wave Open‐Loop Resonator Filters with Reduced Size and Improved Stopband Characteristics

This paper presents a new class of microstrip slow‐wave open‐loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of both ends loaded with triangular and rectangular ends is described, leading to the invention of a microstrip slow‐wave open‐loop resonator. Two‐resonator and four‐resonator bandpass filters are designed at the operating frequency of about 2 GHz, and a bandwidth of 60 MHz. The size of the slow‐wave open‐loop resonator is optimized from the standpoint of the unloaded Q‐factor. The filters are not only compact in size due to the slow‐wave effect, but also have a wider upper stopband resulting from the dispersion effect. The filter designs of this type are described in details. The experimental results are demonstrated and discussed.     

Broadband bandpass filters using slotted resonators fed by interdigital coupled lines for improved upper stopband performances

This paper proposes new broadband microstrip bandpass filters based on slotted linear tapered-line resonator (SLTR) and slotted step impedance resonator (SSIR) structures for size reduction and improved stopband performances. A comprehensive treatment of slotted resonators and both ends of the resonator with interdigital coupled lines is described. The design concept is demonstrated by two filter examples including one with an SLTR and another one with an SSIR. These filters have not only compact size but also a wider upper stopband resulting from resonator bandstop characteristics. The simulated and experimental results of stopband performances are better than 15 dB for a frequency range up to 25 GHz.     

Compact wideband microstrip thinned array antenna using EBG superstrate

A compact wideband microstrip array antenna with EBG superstrate is presented. We compare and summarize the results for the impedance bandwidth and gain characteristics of three different antenna prototypes, namely two conventional 2 × 2 arrays with EBG superstrate and 2 × 2 array of multiple resonator patches with EBG superstrate. The designed antenna has a moderate gain of over 8.5 dBi and a wideband impedance bandwidth of over 20%, which covers the required bandwidth of the WLAN (2.4-2.484 GHz) and WiMAX (2.3-2.5 GHz) systems. The EBG superstrate is also utilized to achieve a thin antenna with a cavity height of λ₀/16 at the center frequency of 2.45 GHz. The proposed antenna is low-cost and low-profile, having overall dimension of 0.9 λ₀ × 0.9 λ₀ × 0.081 λ₀ (110 mm × 110 mm × 9.9 mm).     

Design of a low‐cost 1‐20 GHz magnetic near‐field probe with FR‐4 printed circuit board

An ultra‐wideband magnetic near‐field probe based on a conventional low‐cost four layers of FR‐4 printed circuit board is proposed in this article. It can be used to measure the magnetic near‐field strength from RF magnetic sources or electronic devices for EMI conformance test. The operating frequency of the probe is from 1 GHz up to 20 GHz. The probe is constructed based on a coplanar waveguide and stripline with a short‐end loop. The probe dimension is 10 mm × 25 mm × 0.6 mm. The prototype probe is electric field‐shield structure and has a very high unwanted electric field suppression ratio about 17.7 dB. The probe calibration factor from the simulation agrees well with the calibration factor computed from the measurement. The average probe factor is 38.8 dBS/m and probe sensitivity is 47.4 dB μ A/m.     

Design and Analysis of Antipodal Vivaldi Antennas for Breast CancerDetection

This paper presents the design and analysis of antipodal Vivaldi antennas (AVAs) for breast cancer detection. In order to enhance the antenna gain, different techniques such as using the uniform and non-uniform corrugation, expanding the dielectric substrate and adding the parasitic patch are applied to original AVA. The design procedure of two developed AVA structures i.e., AVA with non-uniform corrugation and AVA with parasitic patch are presented. The proposed AVAs are designed on inexpensive FR4 substrate. The AVA with non-uniform corrugation has compact dimension of mm² or , where is wavelength of the lowest operating frequency. The antenna can operate within the frequency range from 1.63 GHz to over 8 GHz. For the AVA with parasitic patch and uniform corrugation, the overall size of antenna is mm² or It can operate within the frequency range from 1.4 GHz to over 8 GHz. The maximum gain for AVA with non-uniform corrugation and AVA with parasitic patch and uniform corrugation are 9.03 and 11.31 dBi, respectively. The corrugation profile and parasitic patch of the proposed antenna are optimized to achieve the desired properties for breast cancer detection. In addition, the proposed AVAs are measured with breast phantom to detect cancerous cell inside the breast and the performance in detecting cancerous cell are discussed. The measured result can confirm that the proposed AVAs can detect unwanted cell inside the breast while maintaining the compact size, simple structure and low complexity in design.