Thanks! On Wed, Jul 11, 2018 at 4:05 PM, Van Horn, David < david.vanhorn@backcountryaccess.com> wrote: > Very nice! > > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of Sean > Breheny > Sent: Wednesday, July 11, 2018 1:56 PM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Antenna design? > > I would recommend reading appendix A of my master's thesis :) > > https://ecommons.cornell.edu/bitstream/handle/1813/8346/ > thesis%20formatted.pdf?sequence=3D1&isAllowed=3Dy > > It is an 11-page summary of antenna theory (that I had to include because > my thesis advisor was not an antenna expert) > > With an efficient passive antenna (no amplifiers and no major losses that > you can reduce), you can't get more gain without being more directive. In > other words, if you cannot be directional, then making your antenna bigge= r > than a half wavelength does nothing for you. This is true for BOTH transm= it > AND receive because passive antennas are reciprocal devices. > > A patch antenna is probably best for you. Any kind of linear antenna is > going to have a null along the long axis of the antenna. This can be a > problem for the case where the robot is on one floor and the operator is = on > another floor. > > Colinear arrays only make this worse - they direct more radiation in a > flat disk and have an even wider null along the long axis. They are > commonly used for cell towers because all of the cell phones that need to > access the tower are in a narrow range of vertical angle - radiation goin= g > up into the sky (or listening for radiation from the sky) is a waste. > > Sean > > > On Wed, Jul 11, 2018 at 2:37 PM, Neil wrote: > > > Okay antenna gurus, I can use some help here please... > > > > I'm using a 5.8Ghz video transmitter/receiver system on a robot (2D > > driving, indoor). These systems are popular with the drone-racing > > crowd, but most of the good antennas are either circular-polarized (so > > they are uniformly effective at most angles) or patch antennas which > > are apparently very unidirectional. Linear antennas have mostly gone > > away for this purpose. > > > > I'm trying to maximize signal strength/reception so the operator can > > be in a different room and on a different floor. For my purposes, I'm > > thinking a linear antenna on the transmitter side (robot) may be best > > though, as I can mount it vertically in the robot body, and perhaps > > use a patch antenna on the receiver side as that would have minimal > > movement. Or linear as well for the receiver. I understand that whip > > antennas are really crappy so would a straight piece of wire work > > better? I also discovered "collinear antennas" while searching. > > > > I have about 18-20" of room to put an antenna vertically inside the > > robot ... would having an antenna length of a multiple of the > > wavelength work better than just a single-wavelength antenna? > > > > So what say ye? > > > > Cheers, > > -Neil. > > > > > > -- > > 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 .