Joe - you could simply put a directional power meter in-line with the antenna, right at the antenna feedpoint to eliminate the effect of the coax. The forward power minus the reflected power will be the actual power delivered to the antenna. Assuming that the antenna is not faulty or installed near objects which absorb power, this will be close to the actual radiated power. Beyond that, the only remaining variable is antenna pattern= .. On Wed, Jun 4, 2014 at 6:44 AM, Joe McCauley wrote: > Does a spectrum analyser with tracking generator & directional coupler no= t > do the same thing? (Measuring reflected energy from the antenna.) I have > the TG output connected to the through port of the coupler & the antenna > connected on the other side. The coupled port of the coupler is connected > to the RF input of the analyser. > > Thanks, > > joe > > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of Vasile Surducan > Sent: 04 June 2014 09:17 > To: Microcontroller discussion list - Public. > Subject: Re: [OT] Matching an antenna to a VHF TX/RX > > If you have a network analyzer will be much easier. Just connect the > antenna on one port (with the whole cable you are using between the > antenna and the input port) and see the S11. Then tune the antenna lenght > (or adjust the trimmer capacitor if has one) until the max absorption > appears to be on your required frequency. > > I think between 153 and 156 MHz you should do nothing unless you have > small emitting power. > > > On Wed, Jun 4, 2014 at 6:02 AM, Justin Richards > > wrote: > > > On 4 June 2014 03:38, Joe McCauley wrote: > > > > > That is the next step I think, how far apart do you put the > > > antennas? I'm guessing they can't be too far apart. > > > > > > They are close, approx 20 m. If you had a portable B that you could > > position the same distance from each and save trace to disk so you can > > move analyser to the other boat. > > > > I recall that the farming community I once belonged to were adamant > > that a two way radio (UHF) would fail to work if the antenna was > > mounted on the roof of a vehicle and the two way radio was mounted > > directly under the antenna inside the cab. > > > > justin > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .