My RF is 2.4ghz

I have a LC pi filter and a low pass filter ic leading to the 50 ohm antenna

Everything is matched to 50ohm impedance.

Do i need to worry about line length and what distance between stitching vias should i be using to block emi

 

Yes. At these frequencies (GHz not ghz) we talk about transmission line theory, length and width play a crucial role. Layout and stack too.. Length depends on substrate dielectric constant (and frequency of course).

Avoid corners as much as possible in traces, use curves instead. For distance of vias and proper stack, might check some RF PCB guidelines application notes for WiFi/BT modules using these frequency.

 

Often, for high frequency signals on PC board assemblies, there is an effort to configure those high frequency traces as transmission lines. There is a lot of information available on that subject. But not from me.

 

Welcome to AAC.

Investigate mircrostrip and stripline.

 

I do not know what you are doing. When I use ICs that have a 2.4ghz transceivers, there is a recommended PCB layout in the datasheet or there is a separate guide on the PCB/antenna.
This is from TI.

 

View attachment 359124My RF is 2.4ghz

I have a LC pi filter and a low pass filter ic leading to the 50 ohm antenna

Everything is matched to 50ohm impedance.

Do i need to worry about line length and what distance between stitching vias should i be using to block emi

the impedance of the via is probably going to be greater than the impedance of the pi filter.
is the red trace rf also ? why the split ?
the tracks look very narrow for 50 ohms you state.
whats the ground / power plane look like ? is there one below these tracks ?

 

The resonance is related to length, it becomes more critical as the frequency increases. We can add 3% to the length, better to to be long than too short.
an approximation on FR4 microstrip usually microwave or uhf

Free-space wavelength at 10 GHz: 0.030 m
Guided wavelength (ε_eff=2.8): 0.018 m
Half-wave resonant length: 0.009 m (0.9 cm)
Quarter-wave resonant length: 0.004 m (0.4 cm) ----- 0.157 inches

Free-space wavelength at 1 GHz: 0.300 m
Guided wavelength (ε_eff=2.8): 0.179 m
Half-wave resonant length: 0.090 m (9.0 cm)
Quarter-wave resonant length: 0.045 m (4.5 cm) ----- 0.1.77 inches

compared to 100MHz like a fm radio antenna
Free-space wavelength at 100 MHz: 3.000 m
Guided wavelength (ε_eff=2.8): 1.793 m
Half-wave resonant length: 0.896 m (89.6 cm)
Quarter-wave resonant length: 0.448 m (44.8 cm)----- 17.638 inches

compared to 1 Mhz long wire antenna
Free-space wavelength at 1 MHz: 300.000 m
Guided wavelength (ε_eff=2.8): 179.284 m
Half-wave resonant length: 89.642 m (8964.2 cm)
Quarter-wave resonant length: 44.821 m (4482.1 cm)----- 1764.6 inches