Here's a quick guide to build your own Inverted Vee antenna.
I used 433mhz and a 95% velocity factor. You could pair your OpenLRSng Rx/Tx and read the exact frequency to tune the antenna precisely to the frequency you're using.
The dipole antenna uses 1/4 wavelength per wire, so each wire will be 164mm measured from where the shielding ends. Cut your wires slightly longer before attaching, then trim them to length. I cut mine at 18cm.
You can use any wire for this, but I'm using 22awg (that is .025" diameter) lacquered wire.
For the SMA connector, I've taken the stock antennas that came with my OrangeLRS TX/RX, removed the plastic casing and de-soldered the existing coiled antenna from the coax. I then put some heatshrink around the base of the connector and soldered on the laquered wire.
Protip for soldering laquered wire, turn your iron up to 700 or 750 degrees and put a blob of solder on the iron. Touch and hold the blob to the wire until you see the lacquer burn off. Tin the wire as normal.
I have the wires taped to a ruler to get the recommended 120 degree angle between the wires.
60 degrees = .866 we get an "opposite" side length of
147.22mm for a distance between both antenna tips of
170mm * .866 * 2 = 294.4mm
I built a matching antenna for my transmitter, but maybe a 1/2 or 1/4 wave monopole would be better? Any suggestions?