I like to share this information with you because in most cases, I also obtained the ideas and description from third parties.
The very first project I developed was constructin of a couple of yagis for 2m and 70cm bands in order to use them for Satelite operation.
After succesful trials of these antennas I found them useful for other purposes like constesting in horizontal polarisation or repeater operation at long distances.
I found these antennas very interesting as they did not require any gamma match because they are just direct feed at 50 ohm.
Besides, its compact size was really a must for portable operation.
I owe its basics and description to Kent Britain WA5VJB.
You can find all details in its web page http://oldweb.clarc.org/Articles/uhf.htm
Here I just show the details and dimensions of the two antennas I built following his instructions.
Ref and D. are Aluminum dia. 5 mm.
Boom is Wood (resistant enough and lightweight)
The coax is soldered directly in the center point; Braid is soldered in the middle of the long tube and the feed in the extreme of the folded tube.
Nevertheless I use also the VHF antenna itself on a PVC boom when I work Contests. That makes it easier to raise the mast in the country because is lightweight.
Although a visit to the page of its author, Jerry K5OE, is a must in order to get all the feedback and features of this antenna, I offer here just the basic dimensions to be able to build one.
After using it for portable downlink of satellites (AO-51, AO-27, SO-50) I have to say it performs quite well. I can hear the full pass following the satellite trajectory.
(Thanks to Juan Antonio EA4CYQ for the sketch).
When working VHF Contests I found difficult to deal with it when using just one directional antenna. It makes necessary the constant rotation of the antenna to look for the contacts and you can loose some others when tuning frequencies as you are pointing in only one direction.
Then I decided to build one Omni directional antenna. Horizontal polarisation would be a must, as this is the preferred option for contesting. Either a Vertical could have been a solution but the Polarisation os not the correct one for the Contest, loosing many contacts.
When deciding what an easy design would be the best, and after reading about some models available at Internet (big-wheel, HO loop) I had an idea.
I thought that maybe the same design of Clark WA5VJB for standard yagis could be used to make a round omni-directional shape.
I took the same dimension than the driven element for 2m (978 mm) and make one again on Copper rod 3 mm thickness. I mounted it in a Wooden stick to hold it safely. Here you can see the result:
I decided to build one simple antenna to start working with 6m band. My existing antennas were not resonant at that frecuency and then I decided building this one.
The copper has been soldered into an SO-239 connector, and the Glass fiber has been fixed to the connector by means of a bi-component adhesive (epoxy based).
