Dual antennas?


#1


Am I correct in seeing dual antennas? And if so, are they both for the receiver or one for the receiver and another for the fpv?


#2

There are three antennas.
The one in the middle of the rear of the craft is the FPV signal transmission antenna.
The other two antennas are diversity 2,4G antennas for the radio link receiver.


#3

Normally, the large one in the middle of the quad is for the VTX and the two linear ones to the either side of the quad are for the RX.


#4

I just took notice of the third.

So they soldered both to the same connection?


#5

The third one for the VTX is soldered or attached via an RCA or SMA connector to the VTX.

The other two on the side of the quadcopter are soldered or attached via an RCA or SMA connector to the RX. I think these two are attached to separate points on the RX, but I think I’m most cases there is not diversity here, just a redundant antenna for when the signal one one antenna is low because of the quads body interference.


#6

I was hoping the other pics of the build would show in innards but no dice.

I was wondering if that very thing could be done with my up coming build as I was recalling a conversation I had about signal and how it can be blocked by the drone.


#7

Yes. This is always a good practice. If your RX supports dual antennas, route one to either side of the quads body and use shrink wrapped zip ties to keep them in place.


#8

How would I know if it supports it?

This is my intended FC - https://www.banggood.com/Eachine-BAT-QX105-Spare-Parts-AIOF3PRO_Brushed-Flight-Control-Board-Built-in-OSD-Receiver-p-1123480.html?rmmds=cart_middle_products&cur_warehouse=CN


#9

The board that you linked is for a brushed quadcopter. I don’t think that that board supports dual antennas.

You normally see dual antennas on larger brushless quadcopters. For brushed quadcopters weight is normally more important than range, so dual antennas just add unnecessary weight.

What kind of build are you thinking of?


#10

That does make sense. My initial thought was putting two wires to each side soldered to the same point, but I am only 4 months into this hobby so my knowledge in that dept is less than limited.

That’s a finished version. I am working my way up to FPV on a shoestring budget and plan to buy the frame,fc,buzzer with funds from selling a grounded F450 and strip the motors off my CX-30W to get it flight ready. I do not have any FPV equipment as of yet.


#11

Yeah. I don’t think that would work, but let’s check with @Bobnova to be sure.

If your thinking about FPV goggles, I’ve liked my EV800 goggles so far as a decent introductory pair.


#12

Those are on my wishlist, likely to be my next big purchase.


#13

For dual antennas to be useful the receiver needs to have some form of diversity. Diversity in this caae means two reception circuits (one for each antenna) that the receiver can then choose between.
Two antennas attached to one reception circuit doesn’t help signal quality much, if at all, and can easily degrade signal quality.

The quads in the first post have a receiver with two reception circuits, one for each small antenna.


#14

@SinisterLefty, if diversity is really important to you, it might be worth it to get an FC that supports sbus, ppm, or spektrum. Then you can get a receiver with one of those protocols, and get diversity with that.


#15

I honestly do not know what is important or not yet. I read, process, then questions come to mind, then I head for a forum to try to get an answer and make sense of what I’ve read. Forums and YouTube are my only resources.

My flight exp is with a CX-30W toy and Freerider and Liftoff so I’m a work in progress.