UHF antennas (antenn'ae???).. again;-)

cos insects have two of them i.e. plural

owen

Antennae is not the only plural of antenna. You have got to know what you are talking about before you can understand. Consult a dictionary and not one produced by the septic tanks.

PeterD

Maquarie:

antenna /an'tena/, n., pl. -tennae /-'tcni/ for def. 1; -tennas for def. 2. 1. Zool. one of the jointed appendages occurring in pairs on the heads of insects, crustaceans, etc., often called feelers. 2. a radio or television aerial. [L: a sailyard] - antennal, antennary, adj. -antenniform, adj.

Chambers:

antenna, an-ten'a, n. a feeler or horn in insects, crustaceans, and myriapods: in wireless communication, a structure for sending out or receiving electric waves: an aerial:- antenn'ae (-e), antenn'as (radio).-adjs. antenn'al, antenn'ary; antenn'iform; antenniferous.-n. antenn'ule, one of first or smaller pair of antennae in crustaceans.

Yep. Antennas for British and Australian

The diversity of English is inspiring but I need to get out a bit.
Owen

obee

End effect shortens the required length, not lengthens it. The thicker the conductor, the shorter it is for an electrical equivalent length.

PeterD

Yeah I should have said plus or minus or even including. but it was the physics of thing I was referring to not end effect of which I have forgotten with a lot of other things. I was just trying to make it sound simple. I guess I got the rest of it right then.

Owen

All of the pre tuned whips are manufactured to mount on the same base and thus mount on the same base impedance. These are generally designed to operate with the base mounted on a sheet of metal with a diameter of one half wavelength or greater.

If you do not have a suitable ground plane to mount the base, you can create a whip mounting by using a 1/4 wave length (electrically) piece of tube below the feed point. Back in the steam radio days when frequencies were generally lower, we used these 1/4 wave pipes with a 1/4 wave whip on top - we called these co-axial dipoles. when hi-band VHF came into use and antennas were smaller we coupled a dipole to to the top of the whip (with coupling/phasing coils) and constructed an antenna with more gain. With the arrival of the UHF bands we could couple even more dipoles on the top but the basic design of the co-axial mounting sleeve did not change - it just got smaller with the increase in frequency.

It does not matter how many phased collinear dipoles you construct or whether you mount them on a conventional base or a co-axial sleeve, the impedance at the mounting point is the same. The biggest problem is keeping the elements in a straight line - this is impractical at speed with a vary long whip. I consider this is the important consideration for mobile use.

PeterD