SUBJECT: o Hidden Apartment HF Antenna Bottom floor dwellers have some advantages over dwellers on other floors concerning HF antennas. Single unit condo & PUD dwellers fall into this area. Dwellers in the mid-floor(s) have it the toughest. And top floor dwellers have other advantages the first two don't. HF antennas are large and trying to hide one can be like trying to hide an elephant. Many hams try different configurations, snap together antennas, wires, and flag poles to conceal their antennas. Some work out, but most get caught in the end. First, let's look at what you can and can't have. Most restrictive housing areas have a long list of items you can't have. Clothlines, TV antennas, sheds, flags, BBQ grills, etc. And most of all, the all important HF antenna. It has something to do with nice surroundings. Make a list of these items and place them in a column on the left side of the page. Next, list what you can have and list them in the center of the page. Next, list the items that are readly available in the area of your home. Such items are trees, gutters, vents, fences, etc. Look closely and don't leave anything out. A hidden HF antenna must be just that, hidden to the naked eye, even at a point blank range. Next, list the areas that you have a ready access to. If you can get to the roof, write it down. How about the attic, basement, trees, etc, without much notice by your neighbors. Most HF antennas are discovered not because of their design or placement, but rather a neighbor spies the ham installing the antenna or at least doing something out of the ordinary. EX: Creeping around on the roof, on a Saturday afternoon, is going to draw attention. Flinging wires over trees is sure to draw some attention. The big point here is not to install the antenna by looking like your installing an antenna or doing something out of the ordinary. There are some new designs out on the market such as PVC vent pipe antennas for 2m. But for now we'll stick to HF. Most contracts for condo / PUD dwellers will allow bird feeders. And even apartment dwellers on the bottom floor can benifit from this design. I'll give a brief description here of the Bird Feeder antenna and discuss it further in later postings. The Bird Feeder HF antenna is a vertical cage wire antenna. A 'What?' you might ask. Imagine if you will eight flexible wires, evenly spaced in a circular pattern, much like a ground plane. Draw these wires vertically to form a wire 'tube' and connect them together with a ring at the top. Now imagine these wires inside a telescoping PVC mast. Top that off with a bird feeder. Now, instead of a ground plane system with radials you have to put in (the neighbors are watching), you have this 'wire tube' constructed as a vertical dipole. At 10m, the Bird Feeder antenna is a mere 17' tall when raised. What would the neighbors say? Or for that matter the manager? "I raise it up for the birds to get into and it keeps the squirels out too. And look, I can take it out when I'm not using it or the weather is bad. Boy, I really like watching the birds from my window. Did you know that ..." And then go on about some rare, but not unbelievable birds that frequent the feeder. Buy a book on the subject with some pages tagged to show them what you've seen so far. At worst, they'll think you're a flake and leave you alone. Next, go in and tune up 10m and catch some rare DX instead. What do you have to actually put into the ground? Your coax and a PVC pipe to hold the mast up. Make it low in the ground and cap it so the mower doesn't take it off. For te most part, you can leave it up. But do remember to put so seed in the feeder once in a while! I'll give the details next posting and tell you about another right out in the open totally hidden antenna. This one is getting a bit long. ************************************************************************** SUBJECT: Part 2, Bird Feeder Antenna Now, I admit, this design sounds a bit far fetched, but it works. The vertical dipole, inside the PVC push-up, is invisable. It moves up and down and can be removed without drawing attention to the fact that it contains an antenna. The flagpole design has some problems. Not all PUDs, condos, or apartments allow flagpoles. They represent a permanent fixture. Not all associations or managers are that patriotic. Although you can pack a good vertical in a flagpole, there is the problem of radials. You can run the vertical without radials, but that's another compromise. The design for the Bird Feeder Antenna is very simple. Drawing it here is another problem. Ascii Graphics really do not exist, so a description is in order. You can build the vertical dipole without much trouble. The dipole consists of up to 16 wire 1/4 wave elements. There are eight on each leg of the dipole. You may use less, it's up to you. You know the bandwidth of a wire dipole and you know the band spread on 10m. If you are a general or above, you will want the extra wire elements to give you the bandwidth you need. First, let's look at the PVC tubular mast / bird feeder support. Most hardware and home improvement center have PVC tubing. Like the steel counterparts, the mast will be graduated (large at the bottom and smaller at the top. I'm not going to recommend any sizes here as availability at your store is going to dictate what sizes you will need. I will state the the top tube should be 2" in diameter or better. You will need that size to support the bird feeder and give the mast some strength. ___ | | <------- Attach upper ring | | inside | | | | |_| <------- Attach next ring | | inside | | | | | | |___| <------- Attach feed ring inside | |<------- Attach feed ring inside | | | | | | |_____| <------ Attach feed ring | | inside | | | | | | | | |_______| <------ Attach bottom ring inside Figure one. The wire elements are attached in a ring format, evenly spaced, in a 360 degree pattern. Locations are noted in figure one. This allows the dipole to be folded up when the mast is lowered. More than eight wires on each leg of the dipole tends toward snags when raising and lowering. Dipole wire element sizes are calculated by 246 / f Mhz. But I recommend shorter lengths if eight elements are used. A BALUN can be inserted, but is not necessary. I feeder coax is needed from the dipole feed to the base of the mast. A UHF bullet (female to female) to attach your coax to. NEXT: How to lay the coax without looking like you're doing it and Bird Feeder mast install. NEXT ANTENNA: Mobile resonators and hiding them. *************************************************************************** SUBJECT: HF Bird Feeder Antenna, Part three Installing the antenna: The base piece for the bird feeder mast should be one size larger than the bottom section of the mast. The mast should be able to side in a snug fashion, but not too tight. Since you are installing a 'bird feeder', you shouldn't have any problem explaining what you are doing. Simply lay the bird feeder and mast right out in the open. Your nosey neighbors will know exactly what you're doing (almost). The coax is the tough part. Trenches are out of the question. Use a sidewalk edger (manual) and make a thin cut in the grass. If you have other obsticles, you will have to deal with that when you come to it. The object is to do it when the neighbors are not going to notice. The thin cut in the lawn will not be seen and will 'heal' quickly. A tricky technique is to use a wheelblade on a handle. It will look like you are using a measuring device. The cable can be laid into the cut at dawn, when you are filling the bird feeder. Stepping on the cut lawn on the way back seals the cut. Now you're in business. If you have any questions, drop me a line here. Next: Mobile resonators for HF. Their small, they work and they hide well in places you would overlook. And they can be placed right out in the open. ************************************************************************ SUBJECT: VHF & UHF Hidden antennas for PUDs/Condos/Apartments These antennas are much easier to hide because of their size. I'll get into some high level design concepts here and expound on them later. I'll be discussing the following antennas: o Stealth Verticals o Stealth Beams o Indoor Antennas o Indoor/Outdoor use of Mobile Antennas o Field Day / Portable -+------------------------------------------------------------- Stealth Verticals: This type of VHF / UHF antenna is very popular with amateurs. The are easy to build and install. Many commercial antennas are available, but for the dollar, an amateur can build a superior VHF or UHF antenna for the base or mobile use. For the PUD/Condo/Apartment user, even a simple vertical can be a major problem to install. Location in an apartment may be one of the biggest problems facing an amateur when antennas are prohibited. There are large multi-element verticals on the market such as Comet and Diamond. The size of these antennas makes these a bit more difficult to install. There are other homebrew antennas that can be installed however. These antennas will be discussed here. J-Pole The J-Pole is an exceptionally good antenna and easy to build if the directions in the ARRL handbook are followed correctly. One modification I recomend for the J-Pole is to solder the tuning connections after the SWR is set. This allows for 'no maintenance' on the J-pole and no surprizes with SWR changes due to corrosion. 1/4, 1/2, 3/4 wave ground planes These ground planes offer unity, 2dB, and 3dB respecfully. These antennas do not need coils or tuning circuits to accomplish their action. Discones This antenna can be homebrewed or bought commercially. The discone is an excellent antenna, but has it's drawbacks in hiding. The antenna has unity gain and can be used on multiple bands. Vertical Dipole This antenna can be put together in various configurations with various matching devices. The dipole is a halfwave. Full Wave Loop This antenna can be configured to vertical polarization. It is not omni, but exhibits good gain in a bidirectional pattern. There are many more antennas that exist. Some are larger, some don't have the bandwidth, and still others require coils & capacitors to make them work. The aboved mentioned antennas are easy to homebrew and make for good antennas that can be used by PUD / Condo / Apartment dwellers. All the above antennas are in the ARRL antenna book. The design and construction of these antennas is easy if the directions are followed in the book. What I intend to accomplish here is placing the antennas such that they go unseen by all. -+--------------------------------------------------------------------- INSTALLATION OUTSIDE Let's look at the first one: The J-Pole. Gain wise, this antenna does not have a lot of gain on transmit, but the antenna has an easy 3dB gain on receive. If you make your J-Pole from brass rod or like material, placement of the antenna should be accomplished fairly easy. You should remember not to install the antenna near other metal objects or fixtures. Give it about three feet of room from conducting surfaces. The best hidden J-Pole I've seen was painted to match the chimney brick work. Everything that went with the antenna was matched to the chimney. The coax was painted to match not only the chimney, but the roof and then the paint color on the side of this PUD home. The J-Pole was bent to the contours of the brickwork and masonery. The amateur installed the antenna under the cover of cleaning and repairing the chimney. His plan worked well. Another J-Pole I've (almost) seen was mounted to side of a tree at thirty feet. It too was painted to match the bark of the tree. I designed and built a J-Pole for a friend that looked and matched the foliage of a white pine. I used artificial plastic Christmas tree elements to match a branch on the pine tree. If you didn't see where it was installed, you couldn't tell it from the rest of the tree. Another design was mounted to a swing out arm which was installed under a window sill at thirty feet. The Ham painted the J-Pole to match the natural wood finish on the condo. At night, he would swing the J-Pole out from the window and talk on the local repeaters. The dark color of the J-Pole, helped the amateur, by blending the antenna against the night sky. Next, I'll discuss the 1/4, 1/2, 3/4 wave ground planes. These antennas have various gains, but all have one thing in common. Each antenna requires no tuning or matching elements. Like the 1/4 wave, the 1/2 and 3/4 wave antennas are built in the same manor except the vertical element is either 1/2 or 3/4 wave. The Quarter wave 2m antenna can be cut so that it is a 3/4 antenna on the 440-450 MHz band. Thus, a dual band antenna. A 1/4 wave on 222-225 MHz can be cut for a half wave on 440-450 MHz, another dual bander. These dual band antennas will not have the complete range over the secondary band, but will give a piece of it at low SWR. Each antenna will cover the entire primary band it was cut for. I use brass rod for my ground planes. They do not rust and solder easy with a good soldering iron. Hiding these antenna takes a little more foresight. The ground plane shape tends to make the posibilities of a good hiding spot a bit less. But the thin material tends good for trees. They can be hidden as part of the tree with plastic leaves and a blending color paint job. Their size is a good contributing factor. UHF vertical ground planes (VGP) tend to hide themselves. A UHF 1/4 wave VGP is a mere 9 inches from the base of the ground plane to the tip of the vertical element. I wouldn't leave them out in the open, but little will have to be done to hide one of these UHF VGPs. -+-------------------------------------------------------------------- Discones have been used outside in restricted areas. Hiding one can present a problem because of the dimentions. I would suggest using these antennas indoors and will discuss them later. -+-------------------------------------------------------------------- The Vertical Dipole is an easy antenna to hide. The shape is easy to bend in with surrounding objects and matching can be accomplished by many means as listed in the ARRL antenna handbook. My favorite is the gamma match. I would recommend this for the 2m and 1.25m antennas. At this point, I must say the gamma match works fine, but at UHF frequencies, a Tee match is better. The gamma tend to loose the bandwidth required up on the 440-450 MHz band. It can be hidden in the same manner as the J-Pole. -+-------------------------------------------------------------------- The Full Wave Loop is another favorite. Although this antenna has the best gain of the previously mentioned antennas, it can present a problem in band width and placement. When palced against a building, the SWR goes up. Cutting and tuning a loop to a band may also present some problems. The bandwidth of a loop may not cover all the frequencies desired if operating the repeaters. The circular loop is the best, followed by the square loop. Triangular loops work well also. The area enclosed by the loop is the main facter in approaching the 50 ohm impeadance required by amateur radio gear today. Please keep that in mind. Geometric shapes in a natural setting tend to 'stick out' to the human eye. Hiding the antenna will require a crafty plan on the part of the amateur. The bidirectional pattern from the loop my hinder the placement if a specific direction is required. Remember the chimney? Good place to start. -+-------------------------------------------------------------------- Enough for now. Next, I will discuss the VHF/UHF hidden beam antenna. I have not discussed 6m, 33cm, or 23cm antennas, but the same application holds. Here's some info on 1/4, 1/2, and 3/4 wave lengths for the bands 6m, 2m, 1.25m, 70cm, 33cm, & 23cm to give you an idea on the size of the antennas you will be dealing with. The formula use does not always relfect the exact length of the antennas involed, but is to be used for sizing only. 1/4 1/2 3/4 f -+---------------------------------------- 6m | 4.73' 9.46' 14.19' @ 52.0 MHz 2m | 1.68' 3.37' 5.05' @ 146.0 MHz 1.25m| 1.1' 2.2' 3.3' @ 223.5 MHz 70cm | 0.55' 1.1' 1.65' @ 445.0 MHz 33cm | 0.27' 0.54' 0.806' @ 915.0 MHz 23cm | 0.194' 0.387' 0.581' @ 1270.0 MHz SUBJECT: VHF/UHF stealth beam antennas Let's look at a couple of points here first. From my last posting, the relative sizes of the different antennas show that hiding a 6m antenna can be a lot more difficult than hiding a 70cm antenna. 6m beams can be large and hard to explain as a TV antenna. Many PUDs/Condos/ Apartments do not permit TV antennas at all. For places that allow TV antennas, I have some tricks that you can do inorder to play on the bands. These tricks will be discussed later. Beams are a necessity in some locations. The gain achieved on a beam can mean the difference between getting in the repeater, digi-node, making a simplex or SSB contact. The easiest installation would be in an attic, but most hams can figure that out. Unless you only require a fixed position, a beam will require a rotor to fully utilize the quality the a beam can provide. Beams are generally single band antennas when used above 10m. I would recommend a log periodic for use on the VHF/UHF frequencies to provide the ham with multi-band operations. There are some problem that must be addressed when working with beams. First, different polarities are required for different operations. FM and packet use vertical while SSB and CW require horizontal. Space communications requires a combination of the two or circular polarization. Second, hiding a beam and it's associated support equipment can be a pain in the butt when the QTH says no antennas. Anything that must rotate is going to draw attention. Fixed beams can be hidden. Rotating beams are going to require a bit more. -+----------------------------------------------------------------------- Remember that size plays a big point when stealth is employed. I'll look at the 2m beam for the examples here and the relation can be applied to the other bands. Horizontal operation: This is the easiest beam to hide. Be sure you know all the rules of your association or apartment before attempting to install a beam. The beam, because of it's polarity, is flat. It can be passed off as a TV antenna for a specific channel. Most people wouldn't know the difference. The outside installation can be accomplished with the basic TV installation. By adding a second rotor, such as an elevation rotor, both vertical and horizontal polarization can be accomplished. I recommend the vertical operation for night time use only. It eliminates the question; "Why is your TV antenna like that?" Stealth operation: You may not be able to put up a TV antenna and must totally hide the beam. Attics are an easy hiding place. Upper rooms are good too. Telescoping elements for portable operation work well. I would like to relate some unique installations to overcome the no antenna rules. This Amateur had a bad time trying to locate any antenna at his dwelling. He lives in an apartment complex. His apartment is on the inside, second floor, of a four story apartment building that is shaped into a large rectangle. ----------------------------------------- | | | | | --------------------------- | | | | | | | | | | | | | | | | | | --------------------------- | | X | | | ----------------------------------------- The X indicates where the apartment is located. There is an apartment on the outside of his. Like I mentioned, he was on the second of four floors. No antennas are allowed outside the apartment. He had a couple of options. One, he could move, but funds weren't there. Two, he could use his noodle to figure out how to beat the system. This ham enjoys UHF operations from 440-450. He also works 2m packet from time to time. Most people would stick to stamp collecting at this point. There are additional problems facing this ham. Windows on the upper floors would expose him to masts, cables and devices to raise or lower his antennas. On top of that, the roof of the building is steeply sloped. Mounting anything up there, let alone getting up there was a problem. A steeply sloped roof means a large attic. The ham in question is an electrician, by trade, and was employed by the owners of the building to rewire part of the top floor hallway lighting. The job was to take place in a weeks time. It was all the time he required to assemble a set of beams, with rotor control. The coax and control cables were to be run down next to the electrical conduit into his apartment. He purchased two beams, a 2m and a 70cm, to facilitate his requirements. A TV rotor was employed to rotate the set and the antennas were mounted side by side. The 2m beam was a simple four element model and the 70cm model was an eleven element model. In addition to the beams, he also installed two omni directional antennas. The total set was mounted to a short mast and base. It took a mere two hours to assemble the system and one hour extra to run the cables. He was in business. He mounted the system over a stairwell and service closet. He also mounted the base over a foam pad to inhibit the rotor noise. This ham is in the Central Florida area. He is a Technician Class operator and has been operating this way for over three years now. This is an example of fixed beam installation: This ham lives in a condo complex south of a large city. No antennas are allowed. His unit is on the second floor of a two floor unit. This ham enjoys 2m SSB. Since he owns the condo, this ham was able to modify the roof of his screened in porch to accommodate a unique masting system that can be raised and lowered from inside the porch. He employed a three section mast made from aluminum tubing. The eleven element 2m beam was fitted with rubber feet under all the elements and the boom. After that, the beam was painted a dark flat grey to blend in with the night sky, even under full moon conditions. The upper mast sections were also painted in the same manner. During the daylight hours, the beam was lowered against the aluminum roof and was well out of sight from the neighbors. At night, the beam was raised enough to clear the top of his roof. Raising the antenna mast took a bit of planning. The roof of the porch was 7'6" above the deck. A pulley system, similar to a patio umbrella device was employed to raise the mast sections. The mast was placed in the center of the roof and a table supported the base. A plastic vine type plant was used to disguise the bottom section along with a planter to finish off the stealth set-up. The coax was run to the planter and then connected to another coax when it was to be used. The ham in question has been operating this way for a few years with good success. The installation of a beam requires thought and planning. I can not give plans for every installation. This is mostly dependent on the amateur. But these ideas may give you some ideas on how to beat the rules and enjoy your hobby. 73, Wayne KB4YLY, EMLab, KSC, FL