Pavel,
Here is a link to a program as m called MOXGEN. It will calculate the dimensions for a moxon given the frequency &wire size. Once done it'll generate an EZ-NEC model for the antenna.
The model should give you a good idea of the gain, beamwidth & front to back
http://www.moxonantennaproject.com/design.htm
I'd be interested I what it tells you.
73 Rick K7TEJ
On March 16, 2015, at 17:05, Pavel Milanes Costa co7wt@frcuba.co.cu wrote:
Hi to all.
Yesterday I was evaluating the construction of a small antenna for portable use on top of the Baofeng UV-5R... at the end I finished with two choices CJU vs moxon for 70cm handheld
After some modeling I choose the moxon over the CJU because: - Smaller - Less wire - Less weight - Less stress for the connector - Just ~0.6 dB down vs the CJU - By far better F/B ratio
After completion of the first "prototype"...
I successfully heard the CW beacon of Jugnu, CO-57, CO-58, PRISM and others.
The fire test will be tonight on SO-50, I know now I will copy ok, but the challenge is eliminate the desense of having two yaguis on a cross boom.
I will test the moxon handheld on RX (UHF) and a Jpole for the 2m uplink with 5W of a handheld.
I have not measured the SWR of the moxon, but with the simulation the measures are not "that critical" for getting a less than 1:2 of SWR over the entire 70cm band (1:3 bandwidth is about 16 Mhz)
The moxon "experiment" is just ~25 cm width and ~15 cm height (may be smaller also, the minimal height is ~10cm + connector) over the Baofeng UV-5R, there is no much stress on the connector.
I used a SMA to BNC adapter (the kind with a rim to fit tight to the radio body) and then a clamp on BNC (male) with a bronze tube as coaxial shield/boom of the antenna.
Wish me luck with the desense problem...
73