Antenna experts, can you identify this one ??

[gordon_s1942]

First try at posting an image but if it shows, its an antenna that was installed at a hotel a few years ago covering either Band 4 and 5 or Band 5 only.
The fellow who installed it claimed he built it. Now whether from his own design or copied I have no idea.
Due to circumstances I have never seen this in use but as far as I know it does work but how good and if only on analog or digital as well I have no idea.
I have a series of other pics showing it a bit closer, particularly how it is feed.



Ok, I thought this was supposed to be a 'thumbnail' ??
To intrigue you if these pics dont show, I call this antenna the 'EGG RING Special'
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Apologies all round, this does work and work well.
The boom is between 8 and 10 feet overall, I think thats a standard Kingray amp on the mast below the antenna so that might give a size comparison.

[Antennaman]

Ahh, now that would be a vertically polarised loop yagi. It seems someone has gone to a lot of trouble to make that up, and I am impressed with the matching network for the feedline.

A little more information may be obtained by looking here.

[gordon_s1942]

Thanks antennaman, fascinating reading which I am not going to pretend that I can really understand all but the basics.
I forgot to mention in the first instance that the reception here is Vertical and I wondered if thats why the feed loop is where it is in relation to the boom.
If I understand those details correctly, this type of construction is polarity sensative as shown in picture of the feed point,so it follows this one here is also polarity sensative with that folded loop on the 'side' making it veritical as opposed to being on the 'top' for Horizontal.
Because of the antenna's size, that support boom is essential and it would have to be considered in the construction and placement of feed point.
So is it 'Home made' or a commercial build antenna and what sort of gain does it have?

[Antennaman]

I have no idea as to the source of this antenna, I merely assumed it was home made. (I have also corrected the mistake regarding polarisation in my original post. The consumption of several glasses of red wine and the hot sun was affecting my vision and reasoning powers).

I first came across one many years ago when a local radio amateur had constructed one for use on 432MHz and it was sitting on the top of his tower. He called it a circular quad at the time, and that is about all I can recall.

Perhaps a small batch of these were imported from another country, as many years ago when aggregation started to happen, someone imported a bunch of JBX-21 multibeam antennas () and flogged them off. We installed a few of these, but I suspect they were one hit wonders as they seemed to disappear as quickly as they arose.

[porkop]

Downeast Microwave make a series of loopyagi's for 900MHz through to about 5GHz got ham usage

[bulbous]

Ahh, now that would be a vertically polarised loop yagi. It seems someone has gone to a lot of trouble to make that up, and I am impressed with the matching network for the feedline.

The driven element/feed system is very interesting - it's a log-cell arrangement for increased bandwidth. From the photograph it's hard to determine if the directors are tapered-length, but I am guessing they are.

Neat !

[gordon_s1942]

Bulbous, Antennaman thanks and I am sorry my pics arent better but its up 40 feet and thats the best magnification my camera can achieve even with a telephoto lens.I have attached another pic of its full length which does give the impression each 'Ring' starting at the front does increase slightly in diameter towards the feed point and then those rings on the feedpoint most definatly increase ring by ring.I can say that it certainly appears to taper from the front when you stand under it.This antenna has been there now for possibly 10 years and is side on to the weather pattern that occurs here in the Central Tablelands at 950m, snow,ice,frosts,near gale force winds and temps from minus 10C to 40C and that all before lunch on somedays.Whoever built it did a good job as it seems to be as structually as good as the day it was installed.I can understand why he insisted on installing the antenna itself and I never heard the cost but I did the get the distinct impression it was not 'El Cheapo'.Again my thanks to you both for your replies.

PS, antennaman, it will be a cold day in Austech when a fellow cant have a nice quiet drink and enjoy the sun, even if it does soften the edges of reality. ENJOY !!!!

[vmark]

Just another Loop Yagi... very common on UHF & Microwave bands.
1296Mhz is a good spot to start at, after 23cm the better way is to go horns and dishes.