A dipole is not "somewhat directional"--it's absolutely directional.
It has its major lobes perpendicular to its axis. It has extreme nulls
off the ends. It is, by definition, directional.
A dipole has no gain. In fact, it is the real world reference to which
other antennas are compared to determine their gain. The isotropic
radiator, while interesting to consider in a theoretical sense,
doesn't (and can't) exist. While useful for theoretical modeling, it's
sole purpose in the real world is to make an antenna with gain (Yagi,
LPDA, rhombic, etc.) seem like it has more gain by making the
comparison not legitimately to a dipole, but hyperbolically, to an
Nothing more amusing to me than to see the theoretical dBi (decibels
of gain in reference to an isotropic radiator, which doesn't exixt)
applied to a dipole. Geez, it's a dipole. It has no gain. dBi,
particularly when discussing a dipole, is essentially a worthless
"value." And to further make the point, when one tosses out the
calculated dBi, the antenna used as a reference is almost universally
the dipole (dBd). That's why it's so amusing. One might as well say a
dipole has zero gain when compared to a...dipole. Duh! can anyone
Zero similarly doesn't exist in older number systems. Even they learned the
errors of their ways, or at least succumbed to natural selection pressures
in their own way.
Dipoles have non-uniform directivity. It would make a lousy basis of
Is the radiation pattern of a dipole uniform in all directions? If not,
which single gain value would you use for as the base reference gain? You
have this completely backwards. Marketing benefits from a single figure of
merit, some "gain" value over a dipole or some other value. It makes sense
to you and me as some indication of its performance in presumably the
Antennas are passive devices. Forward gain comes from accepting energy from
one direction while rejecting energy from other directions. (Simplisticly
speaking, since nits count.) By itself, it says very little about the
antenna. The single figure of merit is meaningful mostly for marketing. A
picture here is worth a few thousand words. Have a look at
If you don't understand the concepts of antennas (dipoles in
particular) and lobes, there is no point in discussing this further.
Go buy those antennas with 2.1 dB more gain (*calculated*
against...thin air) than the identical product of their competitor
(*measured* against a real life antenna)r. You're a perfect subject
for their market.
Remember way back when the TV experts in the stores preached that you need a
COLOR TV antenna for best reception on one of those NEW style Color TV's?
They are at it again with the Digital TV's. Our 15 year old rabbit ear
antenna works fine on our LCD. I believe that perhaps an old out doors
antenna that has been fighting the elements may be out done by a brand new
antenna but the digital signal requires no better antenna than analog as you
With the change to digital comes new frequencies. Your rabbit ears are
designed for VHF. The digital transmissions are on UHF. If you are in a
strong signal area, your rabbit ears may continue to work. If not, you will
need a new antenna.
I get about 30 channels in Houston however most of the antennas are about 8
miles away "as the crow flies". Oddly with a similar antenna and with an
analog TV the reception for 3 of the 5 major network stations was terrible.
I added a $50 digital tuner to that TV and with the same antenna the
reception was perfect.
My father lives 2 miles from me, added the digital tuner, and a $50 set of
"digital" rabbit ears and the reception sucks if you stand too close or too
far away. The antenna is located near the ceiling.
Narrower bandwidth at same or less transmit power results in lower
received signal strength.
Two other ways of coping with the problem are to use a signal
pre-amplifier and using a directional (gain) antenna.
I can't pick up PBS even with a pre-amp, so plan to build a quad antenna
that should deliver about 21db of forward gain.
The digital receiver only has to determine if the bit is a "0" or a "1"
so the signal doesn't have to be as strong as with an analog receiver.
I've got an antenna with a variable pre-amp. Using that antenna I have
to turn the gain to minimum to receive anything. Even at minimum some
station drop in and out. If I raise the gain I loose the signal
completely. I suspect the signal is still being over driven and
clipping. A plain old $9 antenna works perfectly on all the stations in
Are you reading this some where? Do you actually have digital? I have had
digital for close to 4 years and if I am getting bad reception the picture
is all kinds of terrible, you would swear you were doing mushrooms when this
Satellite has been digital way longer than that. But I have been watching
local digital directly from local broadcast with rabbit ear for almost 4
years. It was just a couple of stations to begin with, the local
advertising, local news, and day time was in standard. Most prime time
was about the only time you could watch in HD.
Yes they have, and most of the rest of the country as well.
And my personal experience with digital is that there's perfect picture,
frozen picture, or black screen. I've never seen anything that looks like
"doing mushrooms" however I am willing to grant that there may be some sets
out there that show pixelation when they lose bits.
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