SHORTY 80 -10m EFHW ! Field test. скачать в хорошем качестве

SHORTY 80 -10m EFHW ! Field test.

End-Fed Half Wave antennas are very popular nowadays among amateur radio operators , including those living in a small lots or operating portable activating summits, parks and reserves on the air. The full size half wavelength antenna on 80m band would make some 40 meters long. The Youtuber Mike-M0MSN published a shortened version of the EFHW antenna on his channel. I liked the idea with using the loading coil in order to make the 40m band EFHW antenna electrically longer and become suitable for the 80m band EFHW antenna operation. I've built and tested antenna in the field while activating one of the World Wide Flora Fauna program references. It proved to be a real success giving me very good coverage of local and even more distant stations on 80m band and also acting as usual 40-10m EFHW antenna on other bands. While constructing the antenna I used a bit different values of dimensions from what was proposed in Mike's-M0MSN video. Instead of 110 microH of coil inductance I have used around 80 microH and the wire "tail" after the coil I made 3,15m instead of proposed 2m. I did that because I only had such and such piece of the PVC tube for the coil former :). I made then the tuning and pruning of the antenna with the help of the FG-01 Antenna analyzer and found out that the antenna of these dimensions in the Inverted V configuration is nicely resonant on lower SSB range of 80, 40, 20m bands. It was not resonant, naturally, on 30m band with SWR around 6:1. Luckily, this size of mismatch was easily affordable for my miniATU ( construction N7DDC). For the impedance transformer, I was using the commercial 80-10m 1KW transformer by "myAntennas.com". One thing I did not go into detail in the video: this, as any other EFHW antenna does need a short counterpoise! The recommended length is 0,05 wavelength on the lowest band, so it makes 4 meters for the 80-10m antenna. This one counterpoise goes good for all other bands too. If you don't use the counterpoise as some manufacturers suggest , the role of the return path for the antenna current will be taken by the coax cable shield through the effect of the stray capacitance. Such antenna may still work good on QRP but as long as you increase the power up to a 100W the RFI on the shield may unpleasantly surprise you. You've been warned! The conclusion: this antenna physically is actually half-size on 80m band yet is surprisingly efficient allowing for stable European -wide contacts even in early afternoon hours and is also very useful as a NVIS antenna for the local contacts. This is very important in my Flora Fauna activation sessions. This antenna being twice as shorter as would the full size 80m dipole be is very easily deployable and makes less pressure onto the lightweight mast. It still keeps all the features and effectiveness of the full-size EFHW antenna on other bands from 40 to 10 meters. I highly recommend this type of shortened antenna and am going to use it myself in the future portable operations. Thanks for watching this video! Consider subscribing for there is more interesting videos to come, with "Icom IC-7300 In The Field" amongst them! 73! 44! Linas LY2H.