Prior to the year 2000, I maintained all my antenna systems outside, on a backyard tower or rooftop mast. These have included Yagi type antennas for HF and VHF as well as many various dipoles and verticals.
In the year 2000, this all changed when my wife and I purchased a new home in an HOA community that allowed no visible antennas. For the past 10 years I have worked 10 meters with a half wave dipole, made from #8 solid copper wire and hung horizontally in the attic. A similar dipole for 6 meters allows occasional SSB contacts when the band is open. Vertical antennas for VHF and UHF also adorn the attic space. A Comet UHV-4 vertical antenna with 16 tuned radials for 10, 6, 2, and 440 mhz serve as the Echolink station antenna ( see Echolink page ).
In 2010, I decided to design an "outside" HF antenna system that would: (1) cover ALL the HF bands from 160 meters and up, (2) be rather stealthy and low visibility and (3) be easily put up and taken down. After researching antennas on the internet, I decided to try a LONGWIRE antenna and tune it with an autotuner using the ICOM 706mark2G transceiver.
First, to get outside from the 3rd floor hamshack in my home, I decided to "homebrew" a window feed-through. I put in 2, SO-239 feed-though connectors. The design can be seen below:
The connector on the right side connects the 250 foot ground radial counterpoise system to the 4:1 balun. The other connector connects the station coax to the 4:1, (1500 watt) balun. The black insulator that is tied to the feed-through board has a metal ring installed in the other side that will take the 107 foot longwire. A clip will allow the antenna to be easily removed from the insulator. The longwire antenna has a jumper wire soldered to it and the jumper wire has a PL-259 connector at the other end to allow it to be easily disconnected from the 4:1 balun. Below is a picture of the feed-though system as it is looks in the window sill:
The red connector coming from the left side is the ground strap 250 foot radial system and the other inside connection is the black coax coming from the LDG AT-100pro2 autotuner. You can see the clip connecting the 107 foot antenna to the insulator and the jumper wire with its PL-259 connecting to the 4:1 balun.
A random length longwire shouldn't actually be "random". There are certain lengths that will work very well on all bands and certain lengths that will load on some, but not on others. My longwire length of 107 feet is NOT just a random length, it is from a table of usable lengths, worked out by VE3EED. He has published a table of lengths to stay away from and another table of good lengths to use in this article on the web:
I selected 107 feet since it was on his "good" lengths table and also fit inside my backyard.
At the far end of my backyard, I attached a 25 foot iron mast pole with a pulley at the top. The pulley contains a nylon rope with another insulator with a ring attached. This allows me to clip the other end of the longwire to the insulator and hoist it up the pole. Once the antenna is in the air, I simply secure the remaining nylon rope on the fence. Below is a picture looking back at the house from the 25 foot iron pole:
The counterpoise ground radial system feeds from the balun to the ground using a flat, braided ground strap. It easily slips under the windowsill allowing the window screen to remain in place:
The ground strap feeds through the window on the left, while the longwire antenna feeds through the window on the right side. ( note: the antenna in the foreground is a portable, tripod based 6, 2 and 440 Comet vertical with a homebrewed radial base ). I have hidden the ground strap's 3 story drop to the ground behind a rain gutter downspout so that it is virtually invisible:
At the base of the downspout the ground strap wire is soldered to a copper plate that connects to approximately 250 feet of radial wires buried in the backyard. The use of an edger/trencher tool made the laying of the radials a simple and quick task.
When it is time to put up or take down the antenna, the use of clips on each end of the longwire and a cord reel make the whole operation simple and quick:
Below is a picture of the 107 foot antenna rolled up on the cord reel:
From the station equipment aspect the key component to this all-band system is the LDG AT-100pro2 125 watt autotuner. This tuner makes tuning on any of the bands quick and easy. It even came with cables that plug directly into the 706mark2G for both control and working voltage. My hat is off to the folks at LDG for a great product that works as advertised! LDG is located right here in Maryland and I found them to be quick and responsive to my questions when I was trying to decide if their tuner would be a match for my longwire system. Below is a closeup view of the ICOM 706mark2G operating on 7171.30 mhz and the LDG AT-100pro2 autotuner attached to the underside of the first shelf:
The autotuner above is showing RF output with the top row of LED's ( ~75 watts SSB ) and the bottom row is indicating an SWR of 1.1:1 on the longwire antenna.
When the antenna is rolled up and the windowsill feed-through is removed, the only visible remaining portion of the antenna system is the pole at the far corner of the backyard, largely hidden from view by the Leylan Cypress trees.