24+ Dbi antenna, does it work?

I don't think any reasonable length Yagi will give you +24 dBi - - maybe around +17 dBi for a 21 element Yagi, but you usually have to go to a dish to get +24 dBi - - it provides a large capture area.

About the Router, "Booster Amplifier" may be someone's hype since power output is hard to measure. If you have something to compare it to, then results will tell if there's any boosting going on. Otherwise, I would suggest just getting a new Router that you can return if not satisfied.

BANGBANGMAX hath wroth:

I don't believe that thing has 24dBi gain. The picture is intentionally distorted to prevent the average user from calculating the length of the antenna. However, I can make a guess by counting the number of elements (17) by approximately 1/4 wave at 2.4GHz (3.13cm) to yield an overall length of about 55 cm. No way is an antenna that short going to have 24dBi of gain. 14dBi is more realistic. For example, see:

which is roughly the same length and number of elements but only advertises 15dBi gain. They lie.

I just noticed that the antenna on eBay does not have a reflector element behind the driven element. That will work, but not very well.

Incidentally, to get 3dB more gain out of a yagi, you need to *DOUBLE* the length. Assuming the MFJ antenna is the advertised 15dBi gain and is about 45 cm long, a 24dBi antenna would be approximately 360 cm (141 inches) long.

No. Amplifiers cause other problems. You end up with an improved transmit range, but no improvement in receive range. Everyone can hear you, but you can't hear anyone's replies. That's not a problem with antennas, where the gain is (usually) symmetrical between transmit and receive.

BANGBANGMAX wrote in news: snipped-for-privacy@no-mx.wirelessforums.org:

I tend to agree with Jeff Liebermann on this one.

Are you looking for a router & antenna, or just an antenna ?

You can get a 'real' 24dBi grid for $55 US. (Don't know what the shipping/duty to Canada would be.)

Just for fun, I decided to run a simple simulation of a mythical 24dBi yagi. See:

The result was 4.2meters (14ft) long monster antenna with 101 elements Yikes. No wonder nobody sells a real 24dBi yagi.

The beamwidth worked out to about 7.5" degrees in both axes which is slightly wider than a dish with the same gain.

The parameters I used were: Freq: 2400Mhz Gain: 22dBd (same as 24dBi) Reflector: Per DL6WU Director: Per DL6WU Metal Boom (bonded) Boom Dia: 5mm Driven: 1mm dia Parasitic: 1mm dia

Drivel: I actually did build an ultra long 2meter (146MHz) antenna that was about 25 ft long for a hidden transmitter hung. It was two pieces of twisted polypropelene rope, with 1/2 wave (38") pieces of electrical wires suspended between the two ropes. The ropes were then hung between a tree and a telephone pole. It worked great. I suppose someone could buld something similar, with 101 elements, and actually build a 14ft long 2.4GHz rope ladder yagi.

Then again maybe not...

looking at the MFJ antenna - it would be interesting to measure the length of a couple of the elements, and the inter-spacing of the elements...

and then compare that to the photo of the eBay antenna to maybe get an idea of what freq that are using ??

physics is physics - the wavelengths don't change on eBay -