Difference between 5/8 and 3/4 lambda
 

Hello!
wich are the differences between two monoband ground plane vertical antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello

On Mon, 29 Mar 2004 21:13:12 +0200, "Marcello"
wrote:

Hello!
wich are the differences between two monoband ground plane vertical antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello



The 3/4-wave will have a substantially higher takeoff angle.

You can download a demo copy of EZNEC which you can use to see that
at: http://eznec.com

Danny, K6MHE

You should be able to find graphs of the radiation pattern versus
element length in many antenna books. 5/8 wave is the longest you can
make a single element and maintain a single lobe. Beyond that, the
pattern splits into two (and more, when the element is even longer)
lobes. To maintain a single lobe (a "flat pancake" pattern) with a
longer antenna, you need a way to divide the antenna into multiple
elements, and have the current in them all in-phase. You can simulate
a ground-plane antenna in programs like EZNec, and if you just look at
a vertical monopole over ground, or a center-fed dipole in freespace
that's twice as long, you should be able to use the free evaluation
version of EZNec. I'm not sure if the free version allows enough
wires/segments to do a ground plane with radials, but possibly. See
www.eznec.com.

Cheers,
Tom

"Marcello" wrote in message ...
Hello!
wich are the differences between two monoband ground plane vertical antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello

On Mon, 29 Mar 2004 21:13:12 +0200, "Marcello"
wrote:
Hello!
wich are the differences between two monoband ground plane vertical antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello

Hi Marcello,

Try:
http://www.eznec.com/

The FREE DEMO will reveal these differences.

73's
Richard Clark, KB7QHC

Tom Bruhns wrote:
I'm not sure if the free version allows enough
wires/segments to do a ground plane with radials, but possibly. See
www.eznec.com.

For reasonable approximations with the free demo, just skip the
radials and use the mininec ground option.
--
73, Cecil, W5DXP

Thanks to All.
I'll try to use this demo program!
best

Marcello



--
www.rogerk.it
"Ca c'havi chiù codda, attacca u poccu"



"Richard Clark" ha scritto nel messaggio
...
On Mon, 29 Mar 2004 21:13:12 +0200, "Marcello"
wrote:
Hello!
wich are the differences between two monoband ground plane vertical
antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello

Hi Marcello,

Try:
http://www.eznec.com/

The FREE DEMO will reveal these differences.

73's
Richard Clark, KB7QHC

"Marcello" wrote in message
...
Thanks to All.
I'll try to use this demo program!
best

Marcello



--
www.rogerk.it
"Ca c'havi chiù codda, attacca u poccu"



"Richard Clark" ha scritto nel messaggio
...
On Mon, 29 Mar 2004 21:13:12 +0200, "Marcello"
wrote:
Hello!
wich are the differences between two monoband ground plane vertical
antenna
5/8 lambda and 3/4 lambda, with orizontal radilas?(90°).
There is a developing system software to view this difference?
Marcello

Hi Marcello,

Try:
http://www.eznec.com/

The FREE DEMO will reveal these differences.

73's
Richard Clark, KB7QHC


I have found that a 3/4 wl and longer vertical antenna can be quite useful
during periods of "skip". Quite often these antennas will allow you to work
into areas that are not so crowded. Your signal is going places others are
not. This can be a good tool to have.

"Jimmy" wrote in message
. ..

I have found that a 3/4 wl and longer vertical antenna can be quite useful
during periods of "skip". Quite often these antennas will allow you to
work
into areas that are not so crowded. Your signal is going places others are
not. This can be a good tool to have.



3/4 wave on a ground plane has a main lobe about 50 degrees above the
horizon. I have a paper by Inagaki et. al. from the 70's describing a 3/4
wave on a gnd plane if I recall, 1.6 lambda or was it 0.6 from a 60 degree
corner reflector. Built one for 2304 MHZ It gives 18dB gain (probably dBi)
and has a very good 50 ohm match. My dad built one in a 2 foot cube for a
440 antenna gain contest {it was a bit short compared to the paper's
specifications) and won.
--
Steve N, K,9;d, c. i My email has no u's.