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Author Topic: Antenna Suggestions  (Read 295 times)
N1ZHE
Member

Posts: 68




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« on: June 25, 2005, 07:19:00 PM »

I need some antenna suggestions.

I bought a house in 1995 before I became a ham. Selling the house is NOT an option at this time.

My lot is tiny. I currently have a dipole cut for 10-80 meters that can only be installed on my lot one way. Unfortunately, it points northwest/southeast, not so good for my southern Maine location.

Besides the tiny lot, I am located in the lowest point in town. I have my town's main street one block out my front door (with houses between me and Main Street, of course). Main Street is higher in elevation than the roof of my house, by quite a lot!

Out my back door, I have this incredible mountain. I am not in a ham-friendly location, antenna-wise.

I make an occasional contact with my dipole, some surprizingly strong, considering their location and my antenna configuration. But mostly I hear people too far down in signal strength for my to understand, let alone work.

A ham friend at work suggested I might want to invest in a good omni, like a Gap. I could mount it at roof level.

I really don't have any room or finances for towers, beams, etc. Plus, due to the layout of my property, I can only put any antennas on one side of my house, or on the roof. And that's the side where the power lines are, so I must choose my locations carefully.

So Elmers, any good suggestions?

David, N1ZHE
 
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WA6BFH
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Posts: 646


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« Reply #1 on: June 25, 2005, 07:34:03 PM »

As I read you request, I was thinking of the Gap as well. That would be a good bet if you want multiple bands. If you would be happy with fewer wavelength choices, other more efficient designs might be desirable, and less visible also?
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KC8VWM
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Posts: 3121




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« Reply #2 on: June 25, 2005, 08:33:14 PM »

You say you are not in a ham friendly location. Does this mean you have an HOA or does it mean you are not properly zoned for a tower? OR....?

This is important to understand because the answer will determine your best antenna option.






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K0ZN
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Posts: 1560




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« Reply #3 on: June 25, 2005, 08:48:06 PM »

Hi,

Sometimes things seem worse than they are. Number one, keep in mind this is AMATEUR radio for most of us... it is a hobby and we do the best we can from the QTH we are "given".

The fact you have room to put up an 80 M dipole... which, if you have it stretched out in a straight line, is about 135 ft long, is NOT a "small" lot...if you can erect a full size 80 M antenna you are in pretty decent shape and ahead of a LOT of people. Even if you have to put a small bend in the antenna, you seem to have some decent real estate to work with.

Regarding your present antenna.... unless that antenna is very high... like over 135 feet HIGH!!... you have a LOW antenna on the lower bands!!...and the radiation angle is quite High... meaning that if your antenna is only 25 or 30 ft. high (which is quite typical for a lot of hams) it is virtually NON-directional on most of the bands from 14 Mhz down through 80. If you had it at 15' and raised it to 30' it would make almost NO difference in directivity on 80, 40 and 30 M...and not a whole lot on 20M ! That would make it a little more efficient, but it would STILL be NON-direcional. There is so much ground reflection effect on low horizontal antennas that they have LITTLE directivity.

i.e. you are worrying about a problem ("facing NW-SE) that does NOT exist with your current antenna; it is NOT a directional antenna!

Bottomline: MOST horizontal antennas at average "ham heights" are NON-directional on the low bands. ...and in your sitution, this is not all bad due to the terrain surrounding your QTH.

The following comment is meant respectfully and to help you because you need more information than can be picked up with a few quick questions on the internet:

The SINGLE best investment you can make in an antenna for your QTH is to pick up a copy of the ARRL Antenna book (or other good antenna book that explains basic theory) and put in several hours studying basic antenna fundamentals, and particularly RADIATION PATTERNS for specific antennas at specific heights. This is NOT difficult stuff... it is quite clear and straight forward...you just need to put in little time digging the info out.

Unless you are 'armed' with a good basic understanding of how antennas radiate, you are going to have a lot of frustrations. Antennas don't lend themselves well to guess and estimations; they have some very specific characteristics, and in some cases requirements that must be met to work WELL. Again, these basics are NOT complicated, but they must be correctly understood.

Going out and buying a commercially built antenna may NOT solve your problem if you don't understand how the various types of antennas work. It is HIGHLY likely there are several antennas and many INEXPENSIVE antennas you could use or make that would work. Most common wire antennas are very cheap to build; even homebrew verticals are not complicated if you understand them.

Factually, due to the terrain around your QTH you maybe somewhat limited on what can be done on some of the higher HF bands, but you still should have options.

Believe me, a couple of hours invested in some "book time" will pay HUGE dividends in terms of optimizing your antenna situation and ultimately having more fun on the air. Knowledge is the BEST solution to your challenges.

Good luck &  73,  K0ZN

P.S.  staying as far as possible from the powerline is a good move.


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K7VO
Member

Posts: 1010




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« Reply #4 on: June 25, 2005, 09:14:27 PM »

I think there are several ways you can imporve your antenna sitaution given the limitations you have.

1.  Invest in a vertical.  GAP is just one manufacturer, albeit a reputable one which makes some good products.  Look at reviews, talk to other hams, look at prices, and see which one best fits your needs and will not cause neighbor problems.  This may be especially helpful on 160, 80, 60, and 40 meters if your dipole is relatively low to the ground.  There will be some signals that will be stronger on the dipole and other that will be stronger on the vertical.  With a coax switch you can choose and use whatever works best for you on a given band and given propagation conditions at that moment.

2.  You mention 10-80 as one dipole.  If so:  is this a trap dipole or a regular full length dipole for 80m which you tune on other bands using an antenna tuner?  You may be better served with multiple dipoles in a fan arrangement from your current, single feedpoint, each resonant on it's own band.  With the shorter lengths on upper bands (i.e.: 20m, 30m, 15/40m) you may be able to run in a different direction and pick up different signals as well.

3.  See if you can get your existing dipole higher off the ground, particularly at the center.

Any of the above can be used in combination.

FWIW, I live high up on a hill but on a truly tiny city lot in half of a rented 1869 duplex (fully modernized, of course).  It's built entirely in the height and length and the width of my lot, which is on a steep slope, is exactly that of one room, or 13'.  The tallest tree (a big, old tree) in my backyard isn't as high at the top as my roof because of the slope of the land.  I do have a large deck and have a vertical on a mast there which, thankfully, works well, and a random wire run from a top window to the top of the aforementioned tree.  You think you have limitations?  I'd love to have the space for a 40m dipole, let alone an 80m one.  I still make things work.

My height and panoramic view in three directions are wonderful for VHF/UHF weak signal work, BTW Smiley

73,
Caity
K7VO/8
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N1ZHE
Member

Posts: 68




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« Reply #5 on: June 26, 2005, 05:01:20 AM »

To KC8VWM: I meant my location was ham-unfriendly due to the lot location and size. I have no known zoning restrictions.

To K7VO: My dipole is a "Cobra" style. It is 73 feet long, made from 3 conductor rotor wire I purchased from Radio Shack. It is fed with 100 feet of 450 ohm ladder line. See this link for more on it's design: http://www.hamuniverse.com/cobraantenna.html

I could not fit 135 foot antenna in my yard.

Thanks to all that answered.

David, N1ZHE
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N6AJR
Member

Posts: 9921




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« Reply #6 on: June 26, 2005, 11:11:35 AM »

My Gap voyager tunes well on 160, 80 40 and 20 meters. it is made to be ground mounted , is 45 feet tall and worke pretty good, better than a dipole here. It needs 2 sets of rope or philly strand guys, is very bendy untill you get it up. ( as per instructions) but works FB ($450 or so)

the Hustler 5BVT works pretty good on 10 15 20 40 and poorly on 80 ($159 ) so there is 2 answers with lo visibility. and not much room.

or do a fan dipole as high as you can and run the other wires out in an astric or umbrella pattern

http://www.hamuniverse.com/multidipole.html
 
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