does wavelength determine height of antenna

[Nigel Goodwin]

Yep, our local ragchew repeater output is 147.220MHz (input is 147.820Mhz). During my ham career, I have tuned dozens of 1/2λ 2m-band antennas using an swr bridge or impedance analyzer. They always end up being just under 1m long at resonance (~38 inches). 1/4λ antennas such as are mounted on a vehicle end up just under 50cm (19 inches).

Yes, I used a couple of 2M rigs for doing a TV aerial job once (we had to fit the aerial at the top of a hill and cable down through an old quarry and a wood, so communications was helpful)

I simply stripped 19 inches off the end of a piece of coax, and separated the inner and screen to make a simple dipole

 

[magvitron]

From experience a micro strip patch antenna with center frequency 866 Mhz with 10 mhz bandwidth was about 20 cm by 20cm @~8 dBm directive.

 

[JimB]

@~8 dBm directive

Please explain what that statement means.
JimB

 

[magvitron]

The antenna has got a "directive" gain of about 8 Decibel meter. The simulation result of that particular antenna is attached.
A quick goog-fu had this , thank god for google, else I would have to get down with the latex editor.

 

[JimB]

gain of about 8 Decibel meter

OK, but what is a decibel meter ?
JimB

 

[magvitron]

I confused dBi with some other term dbm, what I meant was the forward gain for the antenna. The thing was that , 36dBm was the power we are delivering to the antenna .

 

[HiTech]

... and on the lighter side of the topic:

A certain ethnic technician was seen trying to measure the height of an antenna mast. The bystander saw the technician repeatedly climb the mast, attach the tape measure end and slide back down to the ground whereby every time the tape measure unhooked and fell to the ground. The bystander approach the technician and suggested that he remove the mast, lay it on the ground and take a measurement. The technician very wisely replied, "You wise guy, I'm trying to measure the height not the length!"

 

[davenn]

OK, but what is a decibel meter ?
JimB

LOL no such thing as a decibel metre ( or meter)

as you will be probably aware Jim, but magvitron doesn't appear to be, dBm is dB related to 1mW ( one milliWatt)
his 36 dBm = 4 Watts

cheers
Dave

 

[magvitron]

Yeah I messed up there.

 

[davenn]

no probs .... we all do that occasionally

 

[magvitron]

Thanks mate Goodday!