Hf Antennas For Apartments

[Dallas Querry]

Oneof the biggest problems is the limitations of apartment living. Many older hams have been forced to downsize as well as younger hams who cannot afford a single family home face these challenges daily. I hope I can provide some help for this challenge.

First let us consider the type of apartment. If a first floor apartment- consider moving. Really being on a higher floor is a big help with antennas. OK, well that can be dealt with anyway. Does the apartment have a balcony? How about a screened in porch. Are the windows small, or picture window size? Is there access to the roof? Are the walls concrete, wood or full of steel? Does the apartment management allow antennas? These are valid considerations and will affect antenna choices.

Not all antennas are equal. The half-wave dipole is the basis of comparison for antennas. Mobile whip antennas for HF are usually less than 20 percent efficient. However many apartment dwellers have operated using whips installed on their balconies.

Magnetic loop antennas of 1 to 3 meter diameters have been used successfully even they are about 40 to 60 percent efficient. Larger loops of 30 to 50 feet circumference can be used multiband operation with 60 to 80 percent efficiency. Fortunate amateurs that can install an end fed antenna can see 60 to 90 percent efficiency depending on the frequency of operation.

It is estimated that it takes a 6 dB reduction in transmitted signal for the receiving station to notice a change. Remember that a loss also means received signal loss so it affects your reception also. However, many stations operate successfully from apartments with QRP (5 to 10 watt) transmitters. So if you have a balcony where you can install an antenna, there are several choices.

This is one of the most important considerations. Area for antennas is limited and you will want to keep as low a profile as possible. Your neighbors and landlord may not appreciate the beauty of your ham antenna. Full size antennas are surely prohibitive.

You may want the antenna to be removed when not in use. A wire antenna should not be easily viewed when installed. Wire end fed antennas require a support at the far end. If possible, get the antenna outside.

Mobile whips installed on balcony railings with a wire counterpoise have been used with some success. These are usually monoband antennas and have limited bandwidth unless they are auto-tuned screwdriver antennas. Those are expensive. Also remember mobile antennas are often only 7 to 12 percent efficient.

Small loops are a bit more efficient but again they are expensive unless you do make your own. Good variable capacitors used for tuning are expensive. Efficient loops require large diameter or cross section conductors. They work well on the upper HF bands.

Wire antennas can be dipoles, loops or endfed antennas. Usually there is insufficient room for half wave dipoles, except for ten meters. Shortened dipoles are possible but as the antenna gets shorter the band width get smaller. Many experimenters have found that the dipole as short as wavelength can be efficient if the RF can be matched properly to the antenna. Coils and traps add losses to the antenna.

Another possibility is a shortened dipole about 44 to 50 feet long, center fed with balanced feed line or two lengths of TV coax, using the center conductors as the feed line. The shields should be connected at each end and the shack end grounded if possible.

If each half is wound around a 7 meter telescoping fishing pole the antenna can be mounted on a balcony railing, pointing away from the building. This will make a multiband antenna for 40 to 10 meters. One half can be on the pole and one half hanging vertical also. Just make sure the hanging side does not hit apartments or people below. These antennas require a matchbox to feed RF from the transmitter to the feedline. The internal antenna tuners in most modern transceivers do not have enough range to match them on all bands.

End fed wires are possible using a 49 :1 balun and 33 to 72 feet of antenna wire. The wire runs from the balcony or window to a tree or support away from the building. The antenna should not cross any power lines or be where people can contact the wire.

Verticals or semi-verticals can be installed on balconies. Perhaps a 15 foot aluminum tubing vertical mounted on the railing with a 15 foot wire counterpoise hanging down fed with a tuner and short coax feedline or a balanced line. This should make a good antenna for 20 to 10 meters and possibly used on 40 and 30 meters with less efficiency depending on the tuner.

Antennas for stealth, limited areas or apartments are a challenge but there are many ideas available on the internet. Just allow your mind to think out-side-the-box and visualize different antenna installations.

Good evening Don, very nice post and very informative. I was in a condo for over 8 years and I used the MFJ mag loop antenna. This was the best choice for getting me on the air. The Mag loop is not cheap but it did the job for getting me on the air.

73,

Mike

VE9KK

I live on the 10th floor of a high-rise. I use the MFJ apartment antenna on my balcony that you talk about. It works when propagation is good. My complaint is that the quality of the parts is not good. The coax connector is not robust. Worst of all is the alligator clip that connects the whip to the coil. It is very flimsy and is easily disconnected by the wind. In the winter, the snow and ice are problematic.

a wolf river coil works good in a apartment it can be tuned for 10-80 meters I use this antenna indoors and I have no balcony in my apartment the antenna tunes up on all bands without the need for ground radials and the swr is 1.1-1.8 and I make lots of contacts. I highly recommend this antenna the wolf river coil sb1000 to anyone who is a ham radio operator in a apartment setting 73 marc

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If you are indoors, and you cannot get access to a roof, the circumstances pretty much dictate you will not have good omni-directional radiation. So, you might as well look for an antenna with a radiation pattern that fits your mounting options. In a window, a 180 antenna will work well, on a balcony you might find something with up to a 270 pattern. Also, unless you have a balcony, or outside wall mounting option, be careful about the power you use. Under 5 watts would be best, you don't want to fry your brain with 50 watts into a 9 db gain omni (with at least 1/2 the power being radiated inside tour house/apartment).

In the past, I have used NMO mount type mobile antennas with great luck mounted in the middle of a 14 inch pizza pan. You can buy cheap pizza pans at those Dollar type stores. Get the thing outside if you can, and if you just want to make it temporary, use some kind of C clamp, or vice-grip pliers to clamp it to a railing or gutter, or suspend it from an awning with strings as if it were a hanging planter. NMO antennas on a pizza pan give much better results than a mag-mount.

Can you run coax out of the basement?Getting an antenna out of the building (and as high as possible) is going to make a great improvement.an Ed Fong ladder line J-Pole could be attached to the side of a building (making it very deaf for 180 degrees).

I second the recommendation for an outdoor antenna. It doesn't have to be big. Losing 5dB in gain by using a simple one-foot dipole instead of a ten-foot collinear is easily made up for by the 20dB improvement of clearing the roofline and gaining separation from noise sources. On UHF, clearing the roofline makes a *BIG* difference in simplex range, and a good improvement in repeater range.

When I lived in California one of my buddies lived in an Apartment but had access to a balcony on the top floor. He rigged up some EMT (electrical conduit) tubing which he attached to the railing using large hose clamps and attached a Roll up J-pole to it with some zipties. Worked pretty well we could communicate easily and lived around 20 miles apart. The rules in his apartment complex forbade such things but he figured it was cheap and easy to take down if needed. No one ever noticed it though the whole time he lived there.

No lightning to worry about but induced voltage from lightning is. Grounding is still an important part of any antenna system. Because I am in a condo I used a #4 wire attached to a cold water pipe and grounded the shield on all of my hardlines with bonding kits. Since the UHF and VHF antennas are folded dipoles any static buildup is shunted to ground. The scanner antenna has an add on suppressor for stray voltage.

The performance of the antennas for the most part is great. I regularly talk 40 miles simplex on VHF and work repeaters 50 miles away with little trouble. The results are a little less on UHF, simplex is good for 25 miles and repeaters about 45. UHF can be funny during the winter if we get snow build up on the roof, it cuts simplex distance in half but little change on repeaters. I spared no expense when picking and installing my antennas as the antenna is the single biggest factor in the performance of any radio system.

My Wellbrook is mounted on a telescopic mast about 15 feet above ground level, with a rotor. The W6LVP (using LMR400 coax) is tripod-mounted with an overall height from ground of about 12 feet. It has special filters to prevent strong medium wave signals from bleeding into HF.

I have since added a UK-made loop (essentially a copy of a Wellbrook loop but smaller diameter and made of metal) combined with a W6LVP amp. This W6 amp does not have filtering to block strong mediumwave signals. In all, I have four loops into my Delta switcher, which feeds about two dozen receivers.

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