Indoor Omni Antenna 550-600mHz Suggestions

Like this, or am I missing something? About US$150 or so.

Peter Wieck Melrose Park, PA

PSA: omni antennae do not have gain, because gain is always quoted wrt an omni (isotropic) antenna having gain of 0dB.

Also, I doubt you have a house big enough to contain an antenna for

550-600 milli-Hertz.

For what purpose ?

KenW

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** Wrong. Omni and isotropic are not the same.

Any vertical whip type is an omni and can have considerable gain.

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** 600MHz is a common radio mic frequency.

Flexible vertical antennas with BNC connectors sell for a few dollars.

Co-linear versions with gain are harder to find.

..... Phil

In my experience, when people want to refer to an isotropic or "0 dBi" antenna (which is a purely theoretical reference - no perfectly-isotropic antenna can actually exist) they use the word "isotropic".

In common usage, the term "omni" for an antenna usually refers an antenna such as a monopole or dipole, which has a uniform radiation pattern in a two-axis circular pattern, and is directional in only one axis. I assume that's what the original poster is looking for.

Antenna gain is not always quoted w/r/t isotropic. Some manufacturers quote gain that way (as dBi). Others quote it w/r/t a half-wave dipole (as dBd).

Antenna vendors which quote antenna gain in "dB" (without telling you what they're using as the 0 dB reference) are generally using dBi numbers, because they're bigger by 2.15 and thus look better in the ads :-)

Now, to the original request: as to needing antennas in the 550-600 MHz range (which is what I assume you're looking for since you said "indoor")... that's still part of the US UHF-TV band, I think, and so not one for which small narrow-band antennas would have much of a commodity market, hence not many cheap commercial antennas available (or so I suspect). Most coverage here is probably broad-band (often untuned) receive-only antennas.

How much gain do you need? Receive-only, or is transmission required? Can you satisfy your needs with something as simple as a wire whip of the correct length, soldered to a BNC or similar connector, maybe with a counterpoise wire attached to the ground shell, or a couple of ground radials sticking out sidewise? Does it need to be pretty, or child-safe, or capable of surviving the landing and attack of a hyacinthine macaw? 50 ohm, 75 ohm, or something more exotic?

There seem to be many ways to state antenna gain. Some refference to a

1/2 wave dipole, some to a 1/4 wave vertical, and some to a wet noodle.

I never look at the gain given, but to the physical size of an antenna. This is one case where bigger is usually better.

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** Dipoles are directional - the radiation or pick up pattern is in the shape of a figure 8.

Only if used vertically is it omni.

.... Phil

Please look up what "isotropic" means and how it applies in antenna theory. Then you'll be better informed. Sincerely,

--
J. B. Wood	            e-mail: arl_123234@hotmail.com

Smart-arses trying to explain why omni doesn't actually mean omni... sigh. Some people are just born to be d*ckheads

An antenna is termed omni-directional if it possesses a circular radiation pattern in the azimuthal plane. The same pattern in the elevation plane can be doughnut-shaped or something else. An isotropic antenna is a theoretical construct with a spherical pattern in 3-space. As its pattern is spherical, it's useful as a basis for comparison of antenna gain (azimuth & elevation). Gain expressed in "dBi" designates the units for this comparison. An isotropic antenna can be approached in practice using 3 orthogonal electrically-small (in terms of a wavelength) dipoles or loops (often called "magnetic" loops by ham radio operators). Sincerely,

--
J. B. Wood	            e-mail: arl_123234@hotmail.com

Like you.