Hacking an aerial coupling lead & how does this affect the overall performance??

[NW27]

Hi,
I will start by painting the scenario.

WiFi System with an Access Point (AP), coupling lead and a monopole anetenna.
So for 2.4GHz, a 1/4 wave is ~30mm ie 150 *0.97 / 2400 / 2 = 30.3mm.

AP with SMA ...... 500mm Coupling Lead ....... SMA typical small stuby aerial.

On the right end of the coupling lead, there is a panel mounted SMA connector. This is mounted onto the chassis.

The problem:
The 0V (Shield) of the AP cannot be connected to the chassis.

Current Solution
The current solution that was put in place prior to my arrival, is midway along the 500mm coupling lead, remove 10mm of shield from the cable.

AP (SMA)OOOOOOOO---OOOOOOOO(SMA Panel mounted)OOStubby Aerial.
OOO=Shielded cable
--- = 10mm of Shield manually removed, core intact.

The issues I see are:
1. No Antenna ground plane reference back to the AP earth.
2. What is the effect on the VSWR?
3. What is now the effective length of the aerial ie the shield from the AP is cut 250mm into the coupling lead, so relative to the end of the AP shield to the tip of the antenna is now > 250mm + SMA length + dipole length (30mm) = ~ 300mm

I would love to have a  Vector Impedance Analyzer (VMA) to find out exactly how the current install performs. Obviously it is not very good, hence my posting here.
Say the Dipole aerial signal does start at the cut ie 250mm from the AP, what does the next section of the shield look like on the leg of the dipole to the antenna

What are your thought's on the performance characteristics of the current install and how to improve the situation?

Thanks,
Neil.

[NiHaoMike]

Bridge the gap with some surface mount capacitors so it appears as a short at RF but open at DC. Or what might work well enough is to wrap the gap in foil tape with plenty of overlap on both sides.