# Notes

04 Nov 2016
http://www.jpss.jp/en/search/

via this link we can conduct MSc or PhD programs in Japan.

Ultra Wideband Antenna Design for Target Detection
04 Nov 2016
Abstract—In this paper, a four-element microstrip antenna array is presented. The array is composed of Wilkinson power dividers which act as feed network along with Dolph-Chebyshev distribution and four identical patch antenna elements. The array elements are properly designed to have a compact size and constant gain against frequency. The simulated results show good agreement with the measured results for the fabricated antenna array. Measurement shows that the array has a peak gain of more than 12 dBi with side-lobe level of −15 dB at 6 GHz. These characteristics make the antenna array suitable for UWB directional uses.

http://www.jpier.org/PIERC/pierc25/06.11090607.pdf

B Kasi1, * and C. K. Chakrabarty2 1Department of Electrical and Electronics Engineering, Kuala Lumpur Infrastructure University College, Kajang, Selangor 43000, Malaysia 2Centre for RF and Microwave Engineering, Department of Electronics and Communication Engineering, Universiti Tenaga Nasional, Kajang, Selangor 43000, Malaysia

Antenna Properties & Terminology
01 Dec 2016
This video was made for a junior electromagnetics course in electrical engineering at Bucknell University, USA. The video is designed to be used as the out-of-the-classroom component and combined with active learning exercises in class. This video covers some of the terminology and equations that engineers use to define the properties of antennas.

Thanks to the producer of the video.

``` 3 dB ≡  1.414 times the voltage    (−)3 dB ≡  damping to the value 0.707
6 dB ≡          2 times the voltage    (−)6 dB ≡  damping to the value 0.5
10 dB ≡  3.162 times the voltage    (−)10 dB ≡  damping to the value 0.316
12 dB ≡  4 times the voltage    (−)12 dB ≡  damping to the value 0.25
20 dB ≡       10 times the voltage     (−)20 dB ≡  damping to the value 0.1```
Using voltage we get: Level in dB: L = 20 × log (voltage ratio)
```  6 dB = twice the voltage
12 dB = four times the voltage
20 dB = ten times the voltage
40 dB = hundred times the voltage```
``` 3 dB ≡  2 times the power    (−3) dB ≡  damping to the value 0.5
6 dB ≡          4 times the power    (−6) dB ≡  damping to the value 0.25
10 dB ≡  10 times the power    (−10) dB ≡  damping to the value 0.1
12 dB ≡  16 times the power    (−12) dB ≡  damping to the value 0.0625
20 dB ≡       100 times the power     (−20) dB ≡  damping to the value 0.01
Using power we get: Level in dB: L = 10 × log (power ratio)```
```   3 dB = twice the power
6 dB = four times the power
10 dB = ten times the power
20 dB = hundred times the power
If you search for the amplification ratio, given the dB value,
then go to the program dB calculation```

Why FR-4 Is Often Inadequate for RF Design
04 Nov 2016
Many times, designers want to use FR-4 for RF and microwave circuit designs. After all, it is less expensive than other materials, like Rogers 4350, and much less expensive than reinforced PTFE composite boards such as Rogers RT/Duroid 5870. However, sometimes it is necessary to spend the money for higher quality circuit board material and processing to get good, repeatable designs. In this paper, to demonstrate the danger of using FR-4 for some designs, I will design a bandpass filter to work in the 2.4 GHz FCC Part 15 band which is typically used for WiFi, Bluetooth, ZigBee, cordless phones, and many other applications. The filter will be designed using the microwave filter design tool that is part of the Keysight (formerly Agilent) Genesys suite of RF and microwave design software. The pass band is defined as 2.4 to 2.483 GHz. I set an insertion loss goal of 3 dB. The filter program first designs a filter which is close to the desired performance, but it must be optimized to get the performance that is closest to the desired performance. In the case of the first filter, I used FR-4 with a dielectric constant of 4.5, a loss tangent of 0.010, and a thickness of 59 mils. The metallization is 1 oz. rolled copper. Figure 1 shows the final, optimized performance.

By Ed Troy, Aerospace Consulting, LLC http://www.rfcafe.com/references/articles/ed-troy/Why-FR-4-Often-Inadequate-RF-Design-Ed-Troy.htm