Thank you to Arty Bishop for submitting news about his recently released Android App called Look4Sat. Look4Sat is a satellite tracker and pass predictor with a focus on amateur radio and weather satellites. The app is free, ad free, and open source on GitHub. Arty writes that he's programmed this as a learning exercise and notes:
I always wanted to have an offline and not bloated satellite tracker on my phone, as carrying the laptop at all times is kinda not too handy.
The app uses predict4java library under the hood and is written in Kotlin. The TLE files are from Celestrak and the transmitters info is from SatNOGS and once they are ownloaded the app doesn't need an internet connection.
The app creation and design is hugely inspired by Gpredict which is an absolutely brilliant piece of software. Thank you, Alexandru!
Obviously there is no ads and it's totally free. Hope more people find Look4Sat useful.
The features include:
Calculating satellite passes for up to one week (168 hours)
Calculating passes for the current or manually entered location
Showing the list of currently active and upcoming satellite passes
Showing the active pass progress, polar trajectory and transceivers info
Showing the satellite positional data, footprint and ground track on a map
Offline first: pass prediction is done offline. It's up to you to decide when to update the TLE file and the transceivers DB. (Updates once a week are recommended)
Back in early 2017 we posted about Manuel's (aka DO5TY / Tysonpower) design for a single band 140 MHz 3D printed carbon fibre Yagi antenna. Today he's submitted a new video about creating a dual band 3D printed carbon fibre cross Yagi antenna for only 20€. Note that the video is narrated in German, but there are English subtitles. He's also uploaded an English text tutorial to his blog, which includes links to the 3D printer STL files.
The antenna is designed to be a low cost replacement for the commonly used Arrow dual band 2m/70cm antenna which is designed for receiving and transmitting to amateur radio satellites. Many amateur radio satellites have an uplink frequency set at around 145 MHz, and a downlink frequency around 435 MHz (and some satellites have the frequencies reversed). So a dual band Yagi is ideal for these satellites. Manuel writes that with his 5W Baofeng handheld he's already made several successful contacts with his new antenna.
Manuel's antenna consists of several 3D printed joints, with a carbon fibre rod used as the main boom. Aluminum rods make up the receiving and transmitting elements. The video also discusses impedance matching and how he uses a diplexor so that there is only one connection required to the radio. The advantage of his antenna over the Arrow is that it is significantly cheaper, and also much lighter in weight.
[EN subs]Carbon Arrow Yagi Antenne - leichte Dual Band Yagi für 20€ bauen