BACKYARD....CITY LOT ANTENNAs I have tried and worked on....ideas for you.
You will see below some scans I made from Articles from
Ham Radio Publications.
These articles are ones that I have tried or am thinking of trying and I think
they are pretty good. (PARTIAL SCANS so as not to violate copyright restrictions (QST)
AN INVERTED L ANTENNA WITH LOW FEEDPOINT IMPEDANCE (abt 90 ohms)
on two bands of choice.  (80 and 40 version  or 160 and 80 version possible)
SEE JULY 1991 QST or
ARRL HANDBOOKS in the mid NINETIES for the original article by AE6C --- GOOD FOR CITY LOTS
Below is the schematic and winding details for the broadband
bifilar transformer for a
TWO BAND INVERTED L that will fit on
an average sized city lot. Iam on a city lot now and I have an
Inverted L up in the back yard. It works fairly well on 80 and 40.
Right now Im just using an MFJ tuner (random wire
configuration) to tune my inverted L. I have wound a T200-2
core as illustrated and tested it with a 90 ohm resistance with
my rf analyser and the circuit below works. The advantage
over using this circuit vs. a tuner in the shack would be to
keep the RF out of the shack.
I didn't have time to build the matching network at the base of
my inverted L (before the snow came) so..I just used my
inverted L with an Mfj tuner indoors and Ive had some good
results with it.
Far End of the wire
antenna goes into the
upper branches of the
large tree at the back
of my yard. I used
brown insulated #14
wire (it is not too
visible) (good!)
SEE JULY 1991 QST or ARRL HANDBOOK in the mid NINETIES for the original
article by AE6C
This Inverted L works
pretty darn good. I feed it
with my MFJ tuner in the
shack.
It is about 100 feet overall
length. The feedpoint at
the end of the antenna
represents a fairly low
impedance on 80 and 40
meters (where I use it
most)

I have a dedicated
matching network in the
works using a home brew
torroid coil 50 ohm to 90
ohm Z match.

Right now I use this wire on
all bands with an MFJ tuner.
When I get my little mini
beam up on the tower I will
use the dedicated matching
network. The dedicated
matching network was was
described in the July 1991
article by AE6C. It also
appeared in early 1990s
editions of the ARRL
handbook. My dedicated
matching network will have a
small power screwdriver
motor to turn a variable
capacitor to very high
capacitance (effective short)
or lower capacitance to
cancel out the inductive
reactance present on 80
meters  because of the 3/8
wave length of the antenna.
On 40 meters the antenna is
a 3/4 wave wire with a
resistive Z of about 90
ohms.                         
This toroid transformer was pretty simple to build.
I tested it with an Autek RF1 Analyser and a 90 ohm resistive load.
The transformer worked well. This type of transformer can be tapped for other impedances as well. I have two taps on this transformer (the red
wire and the black wire).


The ARRL handbook shows a scheme for 52 ohm to
75 ohm transformer for using 72 ohm cable in your antenna system. All these designs use T-200-2 cores.
I used some white teflon plumbers tape to wrap my torroid above. The red tape is red electrical tape.


These transformers can be used to match 72 ohm coax to 50 ohm coax or for the inverted L as per
the AE6C article. The arrl handbooks and antenna manuals have these types of transformers in
several articles on how to build them.
A 160/80 meter version of this inverted L would be about 192 ft long. It
operates on the same principal as the 80/40 version. The feedpoint Z is low
and can be matched by a transformer with a capacitor in series at the low
frequency to tune out the inductive reactance that would be present..or an
automatic antenna tuner could be used.
As per schematic below, I have changed the design a bit. The relay and the original
capacitor changed to a large value variable that can be driven with a slow rpm motor.
At minimum capacitance ranges it should match the antenna on 80 meters (which
would have a slight inductive reactance), On 40 meters the Z of the antenna would
be mostly resistive and about 90 ohms or so. The capacitor at full mesh..about 1200
pf, would be like a dead short on 40. I have to verify this yet in the real world.
IF you look real
close you can see
the antenna wire
againsts the sky
in the picture.
This simple wire antenna worked pretty well for me. My property layout would not
easily allow for a dipole antenna with open wire feed.

I have since replaced this antenna with a little TGM mini beam and I mostly work the
higher bands now.
For the lower bands...I have installed (spring 2009) a butternut
HF2V (modified--beefed up with bigger aluminum tubing and a buried counterpoise.
You can access a link to my low band vertical project..from my main INDEX PAGE
(home page..www.earlandrews.com
Here I am taking down the inverted L and raising a TGM mini beam. The mini
beam works 20,15,10, 6 and even 2 meters. It works reasonably well. I have a
rotator and it does display some front to side especially. It is high up in the
clear above the rooftops and surrounding objects.

My tower is only about 28 ft high and the mast goes up a bit from that.
A low profile setup for a city lot that works well enough for me and the
neighbours dont mind it at all.
IF YOU DONT WANT TO WIND A TRANSFORMER UP
YOURSELF..I CAN DO ONE UP FOR YOU. I would charge
$17 plus postage. I would wind the windings and tap
the coil. This one here is tapped in two places. These
transformers can be used to interface 50 ohm to 75
ohm coax. This one is unbalanced to unbalanced. I also
have smaller torroid cores for a smaller transformer. I
can measure it up with my Autek RF 1 analyser at any
frequency up to 36 mhz.
ABOVE is one possible installation of an inverted L for backyard operation. I don't think the author would mind if I reprinted part of his article and
presented it in my pages..It is from the ARRL handbook or the July 1991 qst article. He fed his antenna with a small box at ground level. It was only a
very temporary antenna for me..so I just fed it end fed with my MFJ tuner. It worked ok for a temporary antenna.

I dont like having the end of a wire antenna comming right into the shack. You do get some RF floating around the shack.

Better to have a remote mounted arrangement like AE6C has with a few resonant ground radials so that you have a ground and radiator away from
the shack. Another thing I would do is make a good choke balun. For the low bands..I would maybe use a commercial isolator from bux com or some
other outfit. You could wind one up with rg 58 on a large 4 inch form or something as well.  KEEPS the RF from flowing or floating on the braid of the
coax and out of the shack.

I can remember one time using an end fed antenna comming right into the window of the shack. I was using my TS130s. It had metallic buttons or
chrome buttons or something like that. The shack was "hot" with RF..so was the rig. I touched one of the TS130s knobs with the tip of my index finger
just to see if I got a shock or something..WELL..I might have got a tickle..I cant remember ..but I DO ABSOLUTELY REMEMEBER A FAIRLY GOOD WHISP
OF SMOKE COMMING OFF THE TIP OF MY INDEX FINGER..!!!!
Above: another part of the AE6C article.

To the side: me pictured..taking my new mini yagi up the tower the
TGM hybrid mini beam (mini quad).

For the lower bands I put up and modified an HF2V vertical antenna.
June 4-2011..I am currently writing this page and this series of
pages from my old web site (www.earlandrews.com) which I
am closing down. There will be a couple of more pages
concerning small backyard antennas as I write them up. ..73
earl ve3ab
LINK HERE BACK TO my index page of
my "FREE" on line magazine
www.ham
elecronicsmagazine.com
Above a sketch of the tv tower outside of my city lot home here in Elliot Lake. I ran my "temporary" wire antenna..up beside the tower
and out. It worked fine. A bit of rf maybe in the shack because the antenna wire itself ran into the basement shack window right to the
antenna tuner.

I did try a brief experiment. I fed the tower and wire like a big J type antenna. The antenna was about 99 ft long and the tower was a big
fat 28 ft or so grounded radiator. It did work on 40 meters. If I wasn't in such a rush with just moving in to my new home..and I was a bit
better organized..I could have written up the swr curves and did some performance tests.

It does work. Maybe..if someone is operating portable for field day and wants to try this type of antenna with an abandonded metal
tower..it might make for a good antenna???
this page (these pages)..back
yard antennas..is being worked
on (June 4th (ish)) 2011.

I should have these two or
three pages finished in a few
days..tnx earl
I don't like wire antennas. I like aluminum tubing antennas.

I have done so much work soldering wires and putting up poles and dipoles
ect..that now..I like a good solid metal antenna that either can stand up to winds or I
can take down (like my vertical) when real bad weather threatens.

Above me working on the coils of the hf2v. It is a rather heavily modified and
beefed up vertical. Above the chunk of railway rail that I bought at a yard sale.

It was previously a boat anchor! I have some boat anchors around here too!!!
Here I made a pretty nifty fold over and somewhat portable vertical out of an old
vertical antenna that I bought for next to nothing at a flea market.

For more pictures and information about my HF2V 80, 40 (and 160 vertical)...go visit
the home page of www.ham
electronicsmagazine.com and look up the article and
web pages about this vertical.

It has a number of copper tubes (12 ft long) soldered together like a spiderweb
with wire. It is more of a buried counterpoise. The antenna works reasonably well
for me. On 160 I use an approximate 65 uh coil at the base. It gets out ok.

I operate a few 160 meter contests and give out points to people. I am not a serious
dxer or contester. I am more of a tinkerer!
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