QRP Station > Antennas
What's your favourite antenna for portable activity?
GM0LVI:
--- Quote from: sm5mek on November 23, 2014, 14:21:05 UTC ---I like my 4 bands vertical, no need of tuner for 17 -40 meter, only use the right connection on the coil. It is easy to build at home. Use 6m fishing pole or hang it in a tree. See more on my home page. 8)
--- End quote ---
Looks good Jenny. Is there any chance that you could post a sketch of the circuit. I might have a try a making one like yours.
GM0LVI:
This served me for several years as my favourite (and only!) portable antenna.
Here’s a 10-20m top loaded GP I made a few years ago. I needed an antenna that was shorter than full size because I often operated from a studio in Greece that had another studio directly above and I didn’t want my antenna intruding on the view above and annoying other guests. I also needed an antenna that would fit into a standard suitcase.
The tubing is salvaged CB antenna parts (bought for next to nothing at a car boot sale). The insulated base section – bottom in the photo, is made from fibreglass tube I’d left over from making quad spreaders. And the coil section is wound on plastic water pipe with wire I salvaged from an electric motor and wrapped in self-amalgamating tape. The top section is an old transistor radio antenna.
Each thin tube section is topped with a small length of wider tube to allow the next section to connect. The wider top sections are riveted to the thinner sections and to ensure connectivity and security a banana plug on a short lead (riveted) connects each section.
I didn’t want to take a set of radials for each band so I cut a set for the lowest band (20m) and then doubled back the wire until it was the theoretical length for the next highest band, cut the insulation so that I could QSY by just clipping a crocodile clip to the bared wire. I repeated this so I had 20,17,15 and 10m covered. I missed out 12m. I were to repeat this construction I’d just wind the radials on formers and mark them at the critical points and this would give a bit added flexibility tuning on site.
The centre core of the coax connects to a wing nut on the bottom tube and the radials to a washer terminal soldered to the coax. The short length of connecting coax terminates in a PL259 connector.
I did the initial tuning at home using an analyser and it was quite a fiddle involving sliding the second section up and down inside the base tube and then fine tuning with the top ‘radio antenna’ section. Once I’d found the critical points I marked the sliding section with felt pen and an engraving tool. You can see the hose clip I use to set the length and prevent telescoping.
For support I’ve used a 5 litre water bottle with a hole in the lid as a base and Velcro (hook and loop) straps to attach to balcony uprights. I’ve found that the ‘radio antenna’ top section has an added bonus as it allows me to tilt the top section if I’m near the point of intruding into eye space in the studio above.
There’s a photo of the antenna (and me!) in action on my QRZ page. I can’t say it’s my favourite antenna as I far prefer a full size GP. And the jury has still to decide if the Buddistck I used from that particular studio last June was any better than my home-brew effort. In earlier years.
sm5mek:
--- Quote from: GM0LVI on November 24, 2014, 21:23:12 UTC ---
--- Quote from: sm5mek on November 23, 2014, 14:21:05 UTC ---I like my 4 bands vertical, no need of tuner for 17 -40 meter, only use the right connection on the coil. It is easy to build at home. Use 6m fishing pole or hang it in a tree. See more on my home page. 8)
--- End quote ---
Looks good Jenny. Is there any chance that you could post a sketch of the circuit. I might have a try a making one like yours.
--- End quote ---
All info is on my homepage at adress http://www.sm5mek.se/antenner/four-band-vertical-four-ant/ all in English. Higest fq is radiator and after that i did one coil for every other band on lower fq. Tuned coil by coil with 2 proper ground wire.
KC8AON:
My favorite righ now is a "vertical half rombic" see my post" All band no tuner needed antenna (This is and endfed antenna) on this forum for more information, but its an all band endfed wire that requires no tuner at all. Just put it up and start operating any band you wish. No, its not the most efficient design in the world, but for all band operation including 160 meters, its a great design if you happen to have an all band rig. SWR less than 2:1 10 thru 160 meters and very simple to errect ! Here's a link to my post about it: https://www.qrpclub.org/qrp/index.php?topic=859.0
ON6KZ:
I like my Alexloop magnetic loop antenna. Covers 40m to 10m. Very lightweight and it takes only 2 minutes to put it together.
Restrictions: max. 10 W CW / 20W SSB.
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