Mobile tri-band antenna

[KC3ECJ]

"Gain" might not be desirable. When speaking of whips and vertical dipoles, "gain" antennas might not send the signal where you want it to. In mountainous areas you would likely be better off with a "0 gain" 1/4 wave antenna than a 3/4 wave with "gain".

 

[RFI-EMI-GUY]

There is no standard for the term "unity gain" without reference to something known. Many different and well known antenna mfrs compare unity gain to a dipole, or a 1/4 wave ground plane, an isotropic radiator and other things depending on what direction the wind is blowing. There is no consistency in the industry to unity gain.

Sometimes an antenna mfr will tell you what they call unity and even when referencing a 1/4 ground plane, some mfrs only state 1/4 wave ground plane where others state a 1/4 wave monopole over an industry standard 32ft dia ground plane made to very specific dimensions, which is very different than what we would think of as a 1/4 ground plane.

ERP calculations that go to the FCC or other meaningful recipients do not relate to any "unity" gain antnena. Its either dBd or dBi, with the vast majority using dBi and the info you send to the FCC is labeled EIRP in this case. dBi is universal and can be referenced to linear or circular polarized antennas where dBd does not relate to odd polarizations very well. If there were an antenna industry standard size taco that radiated, and it was repeatable, then "dBtaco" would be an actual standard where "unity" is still fuzzy because its different depending on who you ask.
prcguy

A confusion is what exists in the physical world that is an isotropic radiator other than the sun.

So you have an NIST dipole which is reproducible and is 0 dBd or 2.15 dBi, take your pick. Microwave dish antennas are generally rated in dBi. LMR antennas are generally dBd. Some ham and now WiFi antennas are competativly marketed in dBi because it is a bigger number.

Sent from my SM-T350 using Tapatalk

 

[ur20v]

Thanks for the Austin Metropolitan suggestion. That antenna looks like it's the optimal choice.

 

[cbehr91]

The COMPACtenna works well as a low gain, wideband antenna, and that's about it. It requires a groundplane and some experimentation with the mounting location. It would be handy if you have a meter. If you use it as a base antenna, use either a base conversion kit or use a large metal sheet (like the kind you get at Home Depot) and slap a magnet mount on it.

And yes, I have three of these antennas. If you are looking for outstanding performance on a specific frequency, for instance 2m, you'd be better off getting something specifically tuned for 2m. .