Here is another quadrifilar helix antenna design, this time for ADSB (aircraft mode-S transponder) reception at 1090 MHz. Unlike other antenna types this antenna has a spherical coverage with 120° 3dB beamwidth and estimated peak gain of 4.6dBi at 1090MHz.
Finally my Kickstarter pledge, the piDrive from Gungho Labs, arrived today. While I was very excited I took the chance to install the piDrive to my existing Raspberry Pi server.
Here is another project you might be interested in:
While fiddling with a Beaglebone Black Rev.C I run into a problem while trying to backup the eMMC content to external SD card. eLinux.org provides a description that I followed. However, when booting from SD card, I got only a short flashing USR0 LED and then a steady one. The resulting backup file BeagleBoneBlack-eMMC-image-XXXXX.img.gz was only 1kB in size with zero content.
Here is another DIY antenna, this time for GSM/3G/4G usage. The design was calculated for 800-2100MHz and works well in this range. The antenna has a very broad bandwidth with a low gain and can be used for any application within the frequency range. Since the results are very good even up to 3GHz the antenna is also useful for WiFi. As well as ADS-B (flight radar) because 1090MHz is covered too. In general an excellent antenna for rtl-sdr operations.
Based on this calculator.