Concept for a Next Generation Air Dominance. NGAD - FX - F/A-XX - STEALTH - GCAP - FCAS - SCAF - FSAC - GLOBAL COMBAT AIR PROGRAMME - FUTURE COMBAT AIR SYSTEM - UCAV - UAV - USAF - NAVY - DRONE

DIY: Military UHF SATCOM antenna PART THREE By Steve Douglass By now you might be wondering when I’m going to finally write about the nuts & bolts of building my DIY UHF SATCOM antenna. I mean – isn’t that why you tuned in? To recap, I wrote (and you patiently read) about my motivation and my rant about the high cost of new and surplus antennas, not to mention a little about the cool Uniden receiver(s) (Uniden BCD-998T/BCD-396XT) I intend to use(said) antenna with. So without further delay – I once reasoned that if I ever came across one of the Dorne & Margolin antennas again – if I could just take some photos and (maybe) some measurements I might be able to reverse-engineer one and possibly build my own version. Heck, I had (on many occasions) built home-brew UHF Yagi beams and in fact sold quite a few in the past, offering them for sale on my now (long defunct) Intercepts Newsletter – with many of them still in use today. All it would take (I figured) was some educated-best guess-photogrammetric analysis (with something in the image to indicate scale) and I could probably Yankee-engineer a decent-working-prototype with the final goal selling (either antennas or the plans to build their own) to like-minded UHF MILCOM aficionados like myself. As fate would have it, at an open house (air show) at Cannon Air Force Base I finally (after quite a few years wait) was able to inspect (up close) and take a few photos of another D&M antenna. It was part of a military PR –display – connected to a DAMA portable (man-pack) UHF SATCOM transceiver. I again pumped the airman (in charge of the display) for information about the system and took a few close-up photos. I couldn’t help but notice his raised eyebrows at my more-than-passing curiosity and intense interest in his radio rig he but didn’t say anything. I try to reassure him by saying I was a communications-technology-enthusiast, which (from his reply) he took to mean ham-radio-operator. He tells me (in civilian life) he is a ham. My reply apparently put him at ease as he proceeded to fill me in on more technical details about the DAMA system, even going so far as to show me how to find the elevation and azimuth of the military satellite his rig was communicating through. Later (as I examined my photos) I came to the (false) realization that the antenna must be a simple X-beam design. I guessed (incorrectly) they weren’t much more complicated than the Yagi’s I had constructed. The driven elements looked much like two folded dipoles, attached to a short boom (six feet) situated behind a series of x-shaped directors with a wire-mesh reflector at the back. How hard could that be to replicate? Using the photos as my guide, I experimented and over the years I built many antennas. Although they all worked (as good UHF MILAIR antennas) I was never able to monitor the UHF satellites with any real success. The most I could ever manage were choppy or weak, static filled brief intercepts. My assumption was I just didn’t have the element measurements figured out right. Then one day while doing some research on the Internet I stumbled across this: http://www.marlboroughcomms.com/MCL/Product.aspx?proId=65 Marlborough Communications Limited is a British Company that builds military-communication gear under various government contracts, for both her Majesty’s special armed services as well for us Yanks. Like other companies of this type, seeking lucrative government bid-approval, specifications of all their products are (SOP) posted online in downloadable Adobe Acrobat .pdf form. However, standing out clearly among the usual obtuse list of equipment specifications, frequency ranges and MilSpec nomenclature was something I had never seen - a simplified three-view drawing of their manpack foldable UHF SATCOM antenna known as the AV2040-2 – complete with metric dimensions. CLICK TO ENLARGE: Dimensions! Was this the missing data I needed? I quickly downloaded the .pdf and printed it out. I then took it to my computer guru, Wilhelm Scream (not his real name) since he is to math what Lance Armstrong is to cycling. He took a long look at the three-view and the dimensions posted, produced a set of digital calipers and placed them on the drawing. After a few minutes of caliper(ing) calculating and re-calculating, Scream said, “This drawing is to scale. Within a small degree of error – we could upscale it and use them as blueprints to build your antenna. “ Over the next few minutes, Scream produced the measurements that had eluded me for so long. A slow grin spread across my face when I realized that it was very possible to build a working UHF SATCOM antenna, an esoteric passion to be sure, but one that had been floating around in the back of my consciousness for a very long time. After several brain- sessions with Scream, we drafted up a laundry list of parts we would need, which included: several sections of various-sized PVC piping, aluminum rods of various length, copper wire, RF connectors, RG-6 coax feed-line and flat aluminum bar-stock for construction of the driven elements. Most of the tools we would need to cut, drill and shape our parts, Scream already had – which included electric saws, a Dremel and a drill press. Armed with our list we went to the only place that had everything an Interceptor could need to build a UHF SATCOM antenna system – Home Depot. It took several trips – but soon we had everything we needed – and incredibly I paid something in the neighborhood of $20.00. To be continued in PART 4. READ PART ONE HERE! READ PART TWO HERE! You might also like: The Interceptors Club & the Secret of the Black Manta

Ultimate DIY: Military UHF SATCOM antenna PART ONE By Steve Douglass I remember the first time I saw a Dorne & Margolin UHF portable SATCOM antenna. I know that may seem a bit weird and esoteric (an antenna leaving that kind of lasting impression) but the moment I saw one - I knew I wanted one. It was many years ago at the annual “ROVING SANDS” military exercises held in southern New Mexico. I was there covering the games as an aviation journalist. The world's largest air and missile defense exercise, ROVING SANDS overseen by the JFACC, combines Army, Navy, Marines and Air Force units and pits them against each other over the White Sands Missile Range and Biggs Army Ranges. For many years Roving Sands afforded me a unique opportunity to observe (very up-close and personal) military aviation operations that didn’t require going through the laborious task of obtaining government-vetted-sanctioned press credentials, which is exactly what I didn’t want. Once one is allowed on the inside - you only see the stuff they want you to see. Sure you have better access-but it is chaperoned access. My job (then) was to look for the “unacknowledged” black-project aircraft that were rumored to be involved in the games, reporting for magazines such as Popular Science and Aviation Week & Space Technology. Almost needless to say, my compatriots and I weren’t disappointed- but that’s different story for another day. Anyway, (being a rabid military-monitoring hobbyist) I couldn’t help but spot the uber-cool milspec-looking-fishbone-yagi antenna on a building at the Roswell Industrial Airfield (where the Red Forces were based) pointing up at what I could easily deduce was a military satellite hanging 22,000 miles above the equator in geosynchronous orbit. Later in the week, I summoned up my courage and asked an airman (eating his lunch near the antenna at a picnic table) what it was. Apparently he was the right man to ask. He said it was a Dorne & Margolin portable antenna used for UHF-TACSAT/DAMA voice, data and telemetry work. The airman (a com-tech) was proud of his MOS and even took time from his lunch to show me his radio rig. It was impressive, big and bulky over-built by Harris and looked like you cold have dropped it out of the back of a C-130 without damage. He then graciously demonstrated it for me by doing a radio check (voice) with the Joint Training Analysis and Simulation Center (JTASC) in Suffolk, VA. I was surprised at the high-fidelity and clarity of the return com-check, considering it was relayed off a rotating hunk of spinning metal and wires located some 22,000 miles in space, making the round-trip just under 50,000 miles. As the tech continued with his demonstration, he rattled off a list of technical specifications, frequency ranges and communications parameters and protocols that I’m sure he thought I wouldn’t understand. I played dumb, scratched my head all the while trying as hard as I could to take it all in. He had no idea that he was talking to man who had written a hobbyists guide to military monitoring. As impressive as the radio equipment was, I knew I’d never be able to afford one - even sometime in the far-flung future, when it had become obsolete and sold as surplus. It was kind of like taking a test drive in a Ferrari, all the while knowing you couldn’t even afford a Yugo. But the antenna was a different matter entirely. I did own more than one receiver that could (with the right antenna) intercept satellite signals in the bands the airman had detailed (240 to 310 MHz) and had done so (with very limited success) from time to time. The trouble was – UHF TACSAT satellite downlink transmissions were what was technically described as being (right-hand circularly polarized) making reception on commercial and consumer grade antennas (usually vertically or horizontally polarized) problematic at best. Without getting too technical, rotating satellites have forced the use of circular polarization. The fundamental advantage of circular polarization is that all reflections change the direction of polarization, precluding the usual addition or subtraction of main and reflected signals. Therefore there is far less fading and flutter when circular polarization is used at each end of the link. Over the years I tried building my own high-gain UHF Yagi antennas to receive military satellite communications with very limited success. Main trouble was, as the satellite rotated, the signal would swing out of phase and fade (rapidly) in and out and sound much like a record skipping – making interception just plain irritating. To put it simply, it was like trying to have a conversation with someone riding on a merry-go-round. If you weren’t running along side them (constantly) all you would here were bits and bursts of voice. Radio hobbyists (with more technical knowledge than moi) had built home-brew helical antennas and were reporting (via Internet news-groups) great success but the antennas were difficult to engineer and build, especially for a man who barely squeaked by with a C in high-school algebra. For me, looking at the formulae for calculating the spacing and turns on a helical antenna was like trying to read Greek, but that wasn’t what turned me off to ever attempting to build one. The main problem was, none of the antennas looked like the one I saw at Roving Sands, with the majority of the home-brew designs looking like the coils of razor wire ringing the local prison, plus they were huge -sometimes doubled-arrays hardly portable or easily mounted on the back balcony of my tiny apartment. What I wanted was a Dorne & Margolin (now EDO) portable SATCOM antenna, transportable, easy to set up and tear down – and not to mention – tough-looking and black-like those used by covert operators, Rangers, SEAL teams and DELTA. I wanted an antenna that didn’t say “ham radio operator” but instead said “government spy” and “If I tell you what it is I’d have to kill you – so don’t ask.” type of antenna. Anyways – Over the years I’ve held out hopes that some military surplus outlet advertising on the Internet would acquire one of these beauties (and not knowing what it was) offer it for sale at a reasonable price. A few years ago – it happened. Dorne & Margolin/EDO and Trivec Avant (the major military contractors building SATCOM gear) surplus antennae began showing up sporadically on Ebay. Unfortunately they were snapped up fast (and at premium prices) by the well-heeled radio hobbyists. The going price was around 3K to (for pristine units) with even broken or heavily used and abused specimens going at over 1,000 dollars. Refurbished (and new) antennas can also be (now) bought through various re-sellers, who equip shady-military-security for hire companies like Blackwater/Xe Services LLC. These controversial firms are authorized to communicate with the military via SATCOM in places like Iraq and Afghanistan. Blackheart International (http://www.bhigear.com/) offers a mini-satcom antenna on their site for the walk-away price of $3,000. Heavy-duty antennas (Bigger-more gain) could be had for 5K. I couldn’t (and still cannot) fathom why a simple assembly of electronics and aluminum sticks could cost so durn-much! For the life of me – they looked like a simple X-wing Yagi design. Was there something super-secret or complicated (hidden within the design) that made their construction complicated and thusly (and rightly-so) so expensive? Still, hope springs eternal and I thought it would only be a matter of time before one popped up at a price I could afford. In the meantime – I acquired a new super-scanning radio released by Uniden the BCD-996XT. The 996XT is a computer-controlled-programmable scanner with a 25,000-channel capability. To quote Uniden: "This new scanner significantly raises the bar with much improved APCO-25 digital decoding as well as a host of new features and more memory. For those who like GPS scanning, a feature no other manufacturer offers, you can now enable and disable not only Systems but Groups as well depending on your location (the optional GPS antenna that we sell is required). The radio offers a band-scope feature, a Fire Tone Out search feature to help you determine the tone out frequencies being used, improved Close Call, APCO-25 NAC code decoding, and more. The 996XT is a big leap forward." The main reason I acquired the BCD-996XT was for its digital-decoding capabilities. I run a small news-gathering company for the local and (sometimes national) news media called “The Reporter’s Edge.” Recently, the Texas Department of Public Safety had “gone digital” employing APCO-25 digital encoding. It is my job to scan the public safety bands for their producers and reporters and be a sort of safety net for the breaking-news stories that sometimes fall between the cracks while already over-tasked and under-staffed TV journalists took time to write, edit and produce the news as well have a life that didn’t dictate them spending their sacred off-time with their ears glued to a scanning radio. Since I always have a scanning radio droning on in the background wherever I am- it was only natural I found a way to make my obsession (for intercepting radio communications) pay off. Once the Texas DPS went digital, the only way to listen in on their communications was with an APCO-25 digital scanning radio. The BCD-996XT filled the bill nicely. The BC-996XT didn’t disappoint. In fact I can say without hesitation it is the finest scanning radio I have ever owned, only second to the handheld version Uniden’s BC396XT which I also own. Computer aided scanning software of choice is Butel’s ARC396, followed closely by Freescan. The BCD996XT (with its’ more than ample 25,000 channel capacity) freed my BCT396XT for use as a MILCOM scanner, something I have wanted to do for a long while. I love intercepting military aircraft (MILAIR) and associated communications on all the bands and to have a scanner dedicated to just MILCOM was a real treat. I even went so far as to custom outfit a case (containing an ASUS netbook computer loaded with scanning software) that also housed the BCT396XT making it look somewhat like a retro SAC “nuclear football” capable of sending the emergency action messages triggering WWIII. It comes complete with an Cold-War era SAC badge that General Jack D. Ripper would trade his Cuban cigars to have. Okay, I admit-its’ kind off geeky – but that’s just my way. The “football” does have a utilitarian function. Underneath the netbook are two gel-cell batteries that can power the scanner and computer for up to twelve hours. Both can be charged by plugging it into a wall or a cigarette/accessory plug in an automobile. (C) Steve Douglass Continued soon in PART II YOU MIGHT ALSO LIKE THIS