Time Modulated Linear Array (TMLA) Design

In this chapter, time modulated linear array (TMLA) is presented and discussed in detail where all its theoretical backgrounds are derived. The difference between single and multiple time modulation frequencies of TMLA is shown, where different examples in designing them are presented. In addition, the power and directivity of TMLAs are derived in their closed form. Moreover, the relation between the steering angle of each sideband with respect to the first sideband angle is developed analytically. Also, an efficient mathematical method is presented to design TMLA with desired sidelobe (SLL) and sideband levels (SBLs) with maximum attainable directivity. It is shown that the TMLA can be designed by only controlling its time sequence distributions which is a very good advantage as compared to the conventional antenna array

A good conversion loss and a very high LO-to-RF isolation of 24- GHz single balanced mixer for RF front-end receiver

This work describes the design, analysis and fabrication of a 24-GHz microwave single balanced down-conversion mixer based on Schottky diode, hybrid ring coupler and a wide and deep stopband low-pass filter (LPF). The LPF is composed of three uniform defected ground structures along with a compensated microstrip line. The selected frequencies are 24.125 GHz for RF signal and 24 GHz for LO signal. When the LO and RF signals are injected as 10 dBm and 0 dBm respectively, a conversion loss of 12.85 dB with an LO-to-RF isolation greater than 38 dB is obtained. The measured results agree well with the simulated results and the reported design. © 2011 by Maejo University, San Sai, Chiang Mai, 50290 Thailand

A novel band-stop filter using octagonal-shaped patterned ground structures along with interdigital and compensated capacitors

This paper presents a novel compact microstrip band-stop filter (BSF) based on octagonal defected ground structure (DGS) along with interdigital and compensated capacitors. The proposed BSF has lower and higher cut-off frequencies of 3.4 GHz and 5.3 GHz, respectively. A comparison between simulation and measurement results confirms the validity of the BSF configuration and the design procedure. The compact filter occupies an area of (0.45g × 0.35g) with g = 0.044 m on an r = 3.66 substrate and shows a 44% bandwidth ( 2GHz) and a return loss of 0.1 dB. The experimental results show the excellent agreement with theoretical simulation result

Rectangular patch antenna performances improvement employing slotted rectangular shaped for WLAN applications

This paper describes the effect of inserting a rectangular shape defected ground structure (DGS) into the ground plane of the conventional rectangular microstrip patch antenna (CRMPA). The performances of the CRMPA are characterized by varying the dimensions of the rectangular slot (RS-DGS) and also by locating the RS-DGS at specific position. Simulation results have verified that the CRMPA including RS- DGS had improved the CRMPA without RS-DGS. The return loss (RL) enhances approximately of 100 %, and gain improvement of 0.8 d

Comparative study of three shapes of DGS pattern and design of compact microstrip low-pass and band-pass filters

In this paper, three types of defected ground structure (DGS) units which are triangular-head (TH), rectangular-head (RH) and U-shape (US) are investigated and their characteristics are compared each other. Further, they are used in the design of low-pass filters (LPF) and band-pass filters (BPF) and the obtained performances are examined. The LPF employing RS-DGS geometry presents the advantages of compact size, low-insertion loss and wide stopband compared to the other filters. It provides a cutoff frequency at 2.5 GHz, a largest rejection band width of 20 dB from 2.98 to 8.76 GHz, a smallest transition region and a smallest sharpness response at the cutoff frequency. The BPF based on RS-DGS has the highest bandwidth (BW) of about 0.74 GHz and the lowest center frequency of 3.24 GHz whereas the other BPFs have BWs less than 0.7 GHz