Dorne Magolin 2.4G antenna

I found some locally. Are these any good? I can't find docs.

The price is much too high for an unidentified antenna.

Dorne & Margolin Antenna Technologies was an aircraft avionics and marine antenna design shop on Long Island. They were our major competitor when I was designing RDF equipment. As I vaguely recall, D&M was bought by EDO Corp about 1990(?), which was then bailed out by ITT in 2007 after various scandals:

What that means is that this antenna is rather old and possibly part of a direction finder array. D&M designed quite a few exotic prototypes for various government agencies, which may explain the lack of data.

I have my doubts about the part number and description. Q was their prefix for sprial and helical antennas. The 6 at the end suggests that it is part of a 6 antenna array, possibly an interferometer. See:

for a similar part number on a different band.

> I found some locally. Are these any good? I can't find docs.

They are $15 local, but without specs, not a good investment. The shop has quite a few surplus antennas, the rest being RFID. (900Mhz ISM, and one that around 437MHz.] The radome on this antenna isn't very hard, which makes me wonder if they were used inside something else. I supposed radomes don't have to be hard as nails, but I never bought a

2.4G antenna with soft plastic.

Years ago the same store had some panel antennas where it was hard to determine the frequency. The part number went to a family of devices. Eventually they went from $25 to $5, which is when I bought one to open up. It turned out to be around 1.7G, i.e. cellular. But it was good learning by destroying. The antenna was one of those simple PCB types. Some of these panel antennas are actually air spaced wires internally, which I guess is more expense. Hard to say since the PCB type antennas end up etching a lot of copper in their construction. Maybe the copper can be recovered.

Are you sure it's 2.4GHz? I doubt it from the construction.

The soft plastic tubes are helical antennas with 2 or 4 foil strips spiraling around on the inside of the radome. You should be able to see it by shining a flashlight through the radome. Incidentally, the material is either polysulfone or some other microwave friendly material. You'll see similar construction in GPS quadrifilar helical antennas. The soft plastic variety are made to fit inside some aircraft shark fin antennas.

Such patch antennas look crude, but are rather critical in their dimensions and construction. With care, they can be moved to PCS at

1.9 GHz, or Wi-Fi at 2.4GHz. You'll need a way to sweep the VSWR to trim it onto frequency.

Well yeah, but the spacing between elements won't be the ideal. I forget the brand that claims all air spacing between elements.

Back to the DM antenna, the label says "2.4GHZ ARRAY " "DM Q122-3-6" "Dorne & Margolin, INC" "Bohemia, NY 11716"

So it should be 2.4Gz.

Here is the rest of the stash:

Sensormatic IDANT20TN025 Research Corporation Iridium antenna SAF5340-A-SV 695 03616-001 MTI MT-182016/NRH 430-437MHZ

PATCH-A0025 INTERMEC ANTENNA ASSEMBLY 25-178 902-928MHz

I didn't look up the Iridium antenna since my Iridium unit has a built in antenna. The Poynting PATCH-A0025 looks useful. I need a memory refresh here. Do you point the same cicular polarization antennas at each other for point to point comms? The PATCH-A0025 is a nice broadband design.

site.microcom.us/patcha0025.pdf News to me there is a 430-437MHz RFID band. Something I need to look into later.

Yes. You use the same sense when pointed at each other. However, if you bounce it off a reflector, such as a dish, the sense changes. Of course of both ends have dishes, both change sense, and you're still ok.

I did some Googling and found plenty of RFID products for this specific frequency range. No clue what country allows this but it's not usable in the USA.

I don't have the current rules, but the band 433.05 to 434.79 MHz was designated as ISM in Region I (essentially Europe, Africa and the former Soviet Union). In India, Brazil, and French Overseas Departments in Region II (Greenland and the Americas) it's 433.75 to

434.25 MHz.

Old guy

I remember the reflection rotation reversal, since that comes in handy for GPS reception, i.e. the single bounce reflection will be attenuated.

I was surprised at how good of an impedance match you get with a patch antenna. The price at the shop was $25, not exactly a great deal since they go for about $50 with all the hardware.

I have some spread spectrum 900MHz boxes I got from the "MetroPCS" guy at the now defunct Livermore swap meet. He cleans out shacks for new installations and dumped cool stuff like GPS timing gear. In this case, it is an ethernet bridge in that ISM band. It is a Novaroam router. I don't think I ever fired them up, but the price was right, so they became something to stash and play with later. Checking my PC, I see I downloaded all the data on Novaroam in April 2011, so I guess they are seasoned enough to play with now. I think I got the Novaroam 900.

Reverse polarity TNC! I see they sell on ebay for over a hundred, so $10 for the pair I suppose was a good deal. Item 320776880698

>

I found a datasheet on the DM antenna:

It is 8dbi. However, the datasheet indicates it should be used indoors. Perhaps due to the soft plastic. No weep hole that I could detect.

I got one of these at the same shop a few years ago:

A decent antenna with a hard plastic radome that you could use as a weapon if need be.

> I found some locally. Are these any good? I can't find docs.

I thought it looked familiar:

Made by Tecom. Lower gain than the more common brass tube and coax cable variety due to PCB losses.

L-Com bought Hyperlink Tech in 2007:

and picked up that antenna and others as part of the deal.