Here is another quadrifilar helix antenna design, this time for ADSB (aircraft mode-S transponder) reception at 1090 MHz. Unlike other antenna types this antenna has a spherical coverage with 120° 3dB beamwidth and estimated peak gain of 4.6dBi at 1090MHz.
Here is another DIY antenna, this time for GSM/3G/4G usage. The design was calculated for 800-2100MHz and works well in this range. The antenna has a very broad bandwidth with a low gain and can be used for any application within the frequency range. Since the results are very good even up to 3GHz the antenna is also useful for WiFi. As well as ADS-B (flight radar) because 1090MHz is covered too. In general an excellent antenna for rtl-sdr operations.
Based on this calculator.
This antenna was posted in 2012 on FPVLAB, obviously never made it into the blog…solved. 😉
Just in case someone needs a simple and easy to build ground station antenna, usable with any 433MHz TX, here is a solution:
What you need:
1x Beer can, height 170mm, outer diameter 66mm, top opening diameter 52mm
1x Steel welding rod, 500mm length, diameter 1.5mm
1x BNC or SMA panel mount socket with front side nut
How to build:
– First, enjoy the beer, thats a mandatory step. 😉
– Remove the top cover of the can. In a way, that you keep the outer folded ring.
-Drill a hole in the bottom center to insert the BNC/SMA socket.
– Solder the welding rod to the BNC/SMA center contact.
– Measure the length of the rod including the center contact and cut the overall length to 490mm.
– Insert the socket through the bottom hole and fix with the nut.
– Cover the top opening with some non-conductive material. I used some EPS foam.
– That´s all.
I made a extension pipe with a BNC socket on one end and some tripod adapter on the other. This way I can raise the antenna up to 3m on the tripod.
The antenna connects with a 5m BNC cable to the transmitter.
A fellow pilot uses a second antenna with 433MHz 3DR radio modes to control his APM2.5 plane. He was 3km out already then chickened.
Note, a different size beer can may require a different length of the welding rod.
Got some 433MHz antennas from ReadyMadeRC. Brand seems to be Linx Technologies. From a quick test on the VNA they look promising. Return loss and VSWR looking good at 433MHz. Will see how they behave at range. Download Datasheet
Here is just another way to make a helical antenna. Cheap and easy. Aluminum sheet reflector, cardboard tube and self-adhesive copper tape. Designed and tuned for 1240MHz this helical has 8 turns on a 85mm diameter tube.
Added some eye-candy after flight testing. Performance is excellent. No difference to the wire wound helical I built earlier..